Basic (from TL) Flashcards
Spinal cord anatomy adults and kids
In newborns, the dural sac typically ends at S3 and the conus medullaris at L3. In adults, the dural sac typically ends at S1-S2 and the conus medullaris at L1-L2.
Enzyme/receptor polymorphisms: CYP2C19 CYP2C9 2D6 MC1R OPRM CYP3A4 - and what inhibits it
2C19: PPIs, antidepressants
2C9: phenytoin, warfarin, ibuprofen
2D6: codeine, beta-blockers, tramadol, diltiazem, some anti-arrhythmics
MC1R: red hair, increased response to morphine
OPRM: less response to morphine
CYP3A4: metabolism of most anesthetics, lidocaine, dexamethasone; inhibited by midaz
How is ETCO2 measured? What is it proportional to?
End-tidal CO2 (ETCO2) is measured by infrared spectrophotometry where a wavelength of infrared light is passed through a gas sample and the amount of energy detected is INVERSELY proportional to the gas partial pressure.
driving force to raise the bellows?
exhaled gases from the patient
what is the time constant in anesthesia circuit?
The time constant is the volume or capacity of the circuit (Vc) divided by the fresh gas flow (FGF).
how many time constants to reach equilibrium? what is time constant for iso? sevo? des? n2o?
Time constants also apply to the tissue-blood partition coefficients, meaning the amount of inhaled anesthetic that can be dissolved in the tissues divided by tissue blood flow. The time constant for isoflurane is about 3-4 minutes. Complete equilibrium of isoflurane with any tissue, including the brain, would take 3 time constants (10-15 minutes). For nitrous oxide, desflurane, and sevoflurane, the time constant is about 2 minutes. Brain equilibrium then would take about 6 minutes.
normal serum osmolality
The normal reference range of serum osmolality is 275 to 295 mosm/kg (mmol/kg).
formula plasma osmolality
Plasma osmolality (Posm) = 2 x [Na] + [glucose]/18 + blood urea nitrogen/2.8
composition of commonly used IVF
Composition of several commonly used intravenous fluids:
——————–NS…….LR…….Alb…….Plasmalyte
Na (mEq/L)………154……130……130-160……140
Cl (mEq/L)……….154……109……130-160……98
K (mEq/L)………….0…………4………0………………5
Osmolarity (mOsm/L) 308-310 275 310 294
Lactate (mEq/L) 0…….28………0……………0
alveolar gas equation
PAO2 = (Patm - PH2O) FiO2 - PaCO2/RQ
Patm is the atmospheric pressure (at sea level 760 mm Hg), PH2O is partial pressure of water (approximately 45 mm Hg). FiO2 is the fraction of inspired oxygen. PaCO2 is partial pressure of carbon dioxide in alveoli (in normal physiological conditions around 40 to 45 mmHg). RQ is the respiratory quotient. The value of the RQ can vary depending upon the type of diet and metabolic state. RQ is different for carbohydrates, fats, and proteins (average value is around 0.82 for the human diet).
Decreased MA value on TEG
Maximum amplitude (MA), measures the strength of the fully formed clot. It is the maximal width of the TEG. This reflects clot strength as determined by platelet number and function (primarily) as well as fibrin cross-linking. Normal is 50-60 mm.
Decreased MA values primarily suggest quantitative and/or qualitative platelet dysfunction or, to a lesser extent, inadequate fibrinogen. The best treatment is administration of platelets.
TEG prolonged K value
Coagulation time (K) measures speed of clot formation and strengthening. It is equal to the time from amplitude of 2 mm to 20 mm and relies on fibrinogen. Note that some TEG images show varying lengths for K, but it is always measured to 20 mm amplitude.
Prolonged K values suggest deficiencies of thrombin formation or generation of fibrin from fibrinogen/inadequate fibrinogen. Treatment Cryo
A decrease of the alpha angle has similar implication to a prolongation of K. Measures of clot lysis consistent w/ dramatically narrowing amplitudes and short, tapering rates of fibrinolysis (teardrop configuration) suggest abnormal fibrinolysis. Treatment is with antifibrinolytics.
decrease alpha angle TEG
Alpha-angle is the speed of clot formation, and is represented by the angle between baseline and a line tangential to the TEG at 2 mm amplitude. Like the K value, this relies on fibrinogen. Normal alpha angle is 45-55 degrees.
Prolonged K values suggest deficiencies of thrombin formation or generation of fibrin from fibrinogen/inadequate fibrinogen. A decrease of the alpha angle has similar implication to a prolongation of K. Measures of clot lysis consistent w/ dramatically narrowing amplitudes and short, tapering rates of fibrinolysis (teardrop configuration) suggest abnormal fibrinolysis. Treatment is with antifibrinolytics.
TEG R values
Reaction time (R) is from time zero to initial clot formation, defined as a width (amplitude) of 2 mm. Normal range is 1-3 minutes.
Short R values result from aggressive factor replacement or hypercoagulable state.
Prolonged R values result from coagulation factor abnormalities, factor deficiencies or heparin administration. Treatment consists of giving fresh frozen plasma (FFP).
Pressure of N2O tanks
A full tank of N2O contains 1590 L at a pressure of ~745 psig. Pressure within a tank of N2O will remain at ~745 psig until all liquefied gas is used up.
What is in cryo?
Cryoprecipitate contains factor VIII:C, factor VIII:vWF, fibrinogen, factor XIII, and fibronectin.
hemophilia B
Hemophilia B is an X-linked recessive disorder that results in the deficiency of factor IX, thus factor VIII concentrate would not be an appropriate treatment. Recombinant factor IX is the treatment of choice for hemophilia B.
hemophilia A
Factor VIII concentrate is the mainstay of therapy for hemophilia A and 30% of levels are needed for hemostasis.
hemophilia C
Hemophilia C is a disease that results from deficiency of factor XI, thus factor VIII would not be an appropriate treatment. Prediction on bleeding risk is not possible from factor XI levels alone and replacement with factor XI concentrates can be dangerous due to the increased risk of thrombotic events in certain patient populations.
Line Isolation System
Line isolation systems (isolation transformer + line isolation monitor) protect persons from electrocution by turning a normal “grounded system” (that exists outside the operating room) which only needs a single fault to cause electrocution into a “protected” system in which two faults are needed to deliver a shock. The line isolation monitor determines the degree of isolation between the two power wires and the ground and predicts how much current could flow if a second short-circuit were to develop. An alarm goes off if an unacceptable amount of current to the ground is possible (e.g. the “isolated” system is no longer isolated, but rather is grounded, thus only one additional fault could result in a shock).
First step: unplug the last thing that was plugged in (unless it’s vital obviously)
Boyle’s law
water Boyle’s at a constant temperature and Prince Charles is under constant pressure to be king
Boyle’s law: P1V1 = P2V2 or P ∝ 1/V (at constant temperature and mass of gas)
Charles’ law: V1/T1 = V2/T2 or V ∝ T (at constant pressure and mass of gas)
Gay-Lussac’s law: P1/T1 = P2/T2 or P ∝ T (at constant volume and mass of gas)
Henry’s law: C = kP or C ∝ P (at constant temperature)
Dalton’s law: PTotal = P1 + P2 + P3 + …+ Pn
Charles’ law
water Boyle’s at a constant temperature and Prince Charles is under constant pressure to be king
Note that Charles’ law is similar to Gay-Lussac’s law: Charles’ law states that the volume of a given mass of gas is directly proportional to its temperature when at a constant pressure: V1/T1 = V2/T2 or V ∝ T.
Boyle’s law: P1V1 = P2V2 or P ∝ 1/V (at constant temperature and mass of gas)
Charles’ law: V1/T1 = V2/T2 or V ∝ T (at constant pressure and mass of gas)
Gay-Lussac’s law: P1/T1 = P2/T2 or P ∝ T (at constant volume and mass of gas)
Henry’s law: C = kP or C ∝ P (at constant temperature)
Dalton’s law: PTotal = P1 + P2 + P3 + …+ Pn
Gay-Lussac’s law
Note that Charles’ law is similar to Gay-Lussac’s law: Charles’ law states that the volume of a given mass of gas is directly proportional to its temperature when at a constant pressure: V1/T1 = V2/T2 or V ∝ T.
Boyle’s law: P1V1 = P2V2 or P ∝ 1/V (at constant temperature and mass of gas)
Charles’ law: V1/T1 = V2/T2 or V ∝ T (at constant pressure and mass of gas)
Gay-Lussac’s law: P1/T1 = P2/T2 or P ∝ T (at constant volume and mass of gas)
Henry’s law: C = kP or C ∝ P (at constant temperature)
Dalton’s law: PTotal = P1 + P2 + P3 + …+ Pn
Henry’s law
Henry’s law indicates that at a constant temperature, the concentration of a gas dissolved in a solution is directly proportional to the partial pressure of that gas: C = kP (where k is a solubility constant) or C ∝ P. As the volume percentage of a volatile anesthetic is increased, the alveolar partial pressure increases. An increased alveolar partial pressure, therefore, leads to an increased concentration of the volatile anesthetic in the blood which increases the speed of induction and depth of anesthesia.
Boyle’s law: P1V1 = P2V2 or P ∝ 1/V (at constant temperature and mass of gas)
Charles’ law: V1/T1 = V2/T2 or V ∝ T (at constant pressure and mass of gas)
Gay-Lussac’s law: P1/T1 = P2/T2 or P ∝ T (at constant volume and mass of gas)
Henry’s law: C = kP or C ∝ P (at constant temperature)
Dalton’s law: PTotal = P1 + P2 + P3 + …+ Pn
Dalton’s law
Boyle’s law: P1V1 = P2V2 or P ∝ 1/V (at constant temperature and mass of gas)
Charles’ law: V1/T1 = V2/T2 or V ∝ T (at constant pressure and mass of gas)
Gay-Lussac’s law: P1/T1 = P2/T2 or P ∝ T (at constant volume and mass of gas)
Henry’s law: C = kP or C ∝ P (at constant temperature)
Dalton’s law: PTotal = P1 + P2 + P3 + …+ Pn
normal cvp tracing summary
a wave: atrial contraction, absent in atrial fibrillation
c wave: TV bulging into RA during RV isovolumetric contraction
x descent: TV descends into RV with ventricular ejection and atrial relaxation
v wave: venous return to and systolic filling of the RA
y descent: atrial emptying into RV through open TV
epidural lipophilic vs hydrophilic
Use of epidural lipophilic opioids (e.g. fentanyl, sufentanyl) is associated with a decreased risk of nausea and vomiting and possibly pruritus compared to epidural use of more hydrophilic opioids (e.g. morphine).
indications for FFP
Correction of excessive microvascular bleeding (PT >1.5 times normal, PTT >2 times normal, or INR >2)
Correction of coagulation factor deficiencies if the patient has been transfused with more than one blood volume (approximately 70 ml/kg)
Urgent reversal of warfarin therapy
Correction of coagulation factor deficiencies for which there are no specific replacements
Heparin resistance (antithrombin III deficiency) in a patient requiring heparin
Not plasma volume expansion
TTP
Thrombotic thrombocytopenic purpura (TTP) is a platelet destruction disorder. The inherited type involves a deficiency of vWF-cleaving protease activity (ADAMTS13 deficiency). Fresh frozen plasma is administered in order to replete the ADAMTS13 enzyme. Plasmapheresis may be used to treat the acquired type of TTP as it removes the acquired antibodies that damage the ADAMTS13 enzyme.
innervates the muscles of the larynx below the vocal cords and trachea.
Recurrent laryngeal nerve
branch of the superior laryngeal nerve that is the afferent sensory input to the larynx between the epiglottis and vocal cords.
internal laryngeal nerve
glossopharyngeal nerve
cranial nerve IX. It provides sensory innervation to the posterior 1/3 of the tongue, tonsils, pharynx, and middle ear. It also supplies motor fibers to the stylopharyngeus muscle.
cricothyroid muscle innervated by
The cricothyroid muscle is innervated by the external branch of the superior laryngeal nerve, the external laryngeal nerve.
order gases by blood:gas solubility
Volatile agent blood:gas solubility in order of least to greatest is: Desflurane < N2O < Sevoflurane < Isoflurane.
Volatile anesthetic uptake is ____________(directly/indirectly proportional?) to blood:gas solubility, whereby those agents with higher blood:gas partition coefficients have a _______ faster/slower rate of rise of FA/FI as compared to less soluble agents.
Volatile anesthetic uptake is proportional to blood:gas solubility, whereby those agents with higher blood:gas partition coefficients have a slower rate of rise of FA/FI as compared to less soluble agents.
FA = fractional concentration of alveolar anesthetic, FI = fractional concentration of inspired anesthetic.
2C19
2C19: PPIs, antidepressants
2C9
2C9: phenytoin, warfarin, ibuprofen
2D6
2D6: codeine, beta-blockers, tramadol, diltiazem, some anti-arrhythmics
MC1R
MC1R: red hair, increased response to morphine
OPRM
OPRM: less response to morphine
CYP3A4
CYP3A4: metabolism of most anesthetics, lidocaine, dexamethasone; inhibited by midaz
Formula for compliance of respiratory system
1/CRS = 1/CL + 1/CCW
Where C is compliance, RS is respiratory system, L is lungs, and CW is chest wall.
Myasthenia Gravis
autoimmune disorder with antibodies against the extrajunctional nicotinic acetylcholine receptor resulting in weakness, enhanced response to nondepolarizing neuromuscular blockade, and resistance to succinylcholine but does not result in upregulation of postjunctional acetylcholine receptors.
Effects of glycopyrrolate
Glycopyrrolate delays gastric emptying, decreases salivary and gastric secretions, increases heart rate, relaxes bronchial smooth muscle, decreases lower esophageal sphincter tone, and causes urinary retention.
what enzyme does etomidate inhibit
Etomidate causes adrenal suppression of cortisol production by inhibiting mitochondrial 11β-hydroxylase, preventing the conversion of 11-deoxycortisol to cortisol.
Etomidate inhibits adrenal steroidogenesis by inhibiting the enzyme 11-β hydroxylase which is responsible for cortisol and aldosterone production. Adrenal suppression is most pronounced with long-term use, but can also occur transiently after a single dose.
factors that increase MAC requirement
Factors Increasing MAC: Drug - Amphetamine (acute use) - Cocaine - Ephedrine - Ethanol (chronic use) Age - Highest at age 6 months Electrolyte disturbance - Hypernatremia Hyperthermia Red hair
factors that decrease MAC requirement
Factors Decreasing MAC: Drugs - Propofol, etomidate, barbiturates, benzodiazepines, ketamine - Alpha2 agonists (clonidine, dexmedetomidine) - Ethanol (acute use) - Local anesthetics - Opioids - Amphetamines (chronic use) - Lithium - Verapamil Age - Elderly patients Electrolyte disturbance - Hyponatremia Others - Anemia (Hgb < 5 g/dL) - Hypercarbia - Hypothermia - Hypoxia Pregnancy
Duration of action midazolam vs flumazenil
The duration of action of midazolam (half-life 1.7-2.6 hours) exceeds that of flumazenil (half-life 0.7-1.3 hours).
allergy associated with spina bifida
latex
fenoldopam
Fenoldopam is a selective D1 receptor agonist with direct natriuretic and diuretic properties. Fenoldopam promotes an increase in creatinine clearance and has been employed as a renal protector when renal vasoconstriction is anticipated.
increases renal blood flow despite decreased systemic arterial blood pressure. Fenoldopam has little to no alpha, beta, or dopamine-2 receptor agonist activity.
what to do with extravasation of vasopressors
Extravasation of vasopressors can be managed with limb elevation, warm compresses, irrigating with saline (Gault technique), injection of phentolamine (hyaluronidase if vessicant instead of pressor), and/or a stellate ganglion block (not axillary) (for upper limbs).
what to do with ARTERIAL injection of pressors
TrueLearn Insight : Accidental intra-arterial injection of drugs can cause vasospasm and thrombosis. Management includes injecting lidocaine and calcium channel blocker intra-arterially. A stellate ganglion block can also be useful.
Sarin mechanism
Sarin is a neurotoxin that potently inhibits acetylcholinesterase, causing continual transmission of nerve impulses and inability to control respiratory muscles.
Tetrodotoxin mech
Tetrodotoxin inhibits fast sodium currents in myocytes, thus preventing contraction of respiratory muscles.
boutlinum toxin mechanism
Botulinum toxin can cause symptoms of muscle paralysis by preventing the release of acetylcholine-containing vesicles from the axon terminal into the synaptic cleft.
TrueLearn Insight : Botulinum toxin acts inside the axon terminal at the neuromuscular junction. Tetanus toxin travels via retrograde axonal transport to the CNS where it acts.
tetanus toxin mechanism
Tetanus toxin travels via retrograde axonal transport to the CNS where it acts.
Alfentanil
Alfentanil is an opioid with high non-ionized fraction providing rapid onset and offset. It has a smaller volume of distribution compared to fentanyl (bc lower lipid solubility).
TrueLearn Insight : The clinical pharmacokinetics of alfentanil can be estimated by “4”. Compared to fentanyl: alfentanil has 4x faster onset, is 1/4th as potent, and lasts about 1/4th the duration.
Precedex
Dexmedetomidine has a high specificity for the α2 receptor and provides sedation, anxiolysis, hypnosis, analgesia, and sympatholysis. It decreases HR, SVR, CO, SBP, the incidence of perioperative myocardial ischemia, and reduces perioperative opioid requirements.
Extracellular total body water compartments and percentages
The ECV contains one-third of TBW, represents 20% of total body weight and is composed of plasma volume (20-25%) and interstitial fluid volume (75-80%).
Effect of corticosteroids on: WBC, hemoglobin, blood glucose, K, Na, acid/base status, urinary uric acid, urinary calcium.
Corticosteroids are associated with leukocytosis, increased hemoglobin, hyperglycemia, hypokalemia, mild hypernatremia, alkalosis, increased urinary uric acid, and increased urinary calcium.
Effect of ketamine on Cerebral blood flow, ICP, CMRO2
Ketamine is known to increase cerebral blood flow (CBF), intracranial pressure (ICP), and cerebral metabolic rate of oxygen (CMRO2) due to stimulation of the sympathetic nervous system and excitation of the central nervous system (CNS).
Ketamine asthma
Ketamine is a respiratory stimulant and promotes central respiratory drive. It maintains spontaneous ventilation and provides bronchial smooth muscle relaxation. Ketamine has been shown to be effective in patients with severe asthma and status asthmaticus that is refractory to standard therapy. Ketamine can increase salivation, especially in children, and can potentially lead to a higher incidence of upper airway obstruction and/or laryngospasm.
If PCO2 change by __, then pH changes by ___
If PCO2 change by 10, then pH changes by 0.08
Fa/Fi ratio
The proportion of alveolar (FA) anesthetic concentration to inspired (FI) anesthetic concentration (FA/FI) will rise faster with agents with a lower blood to gas partition coefficient (insoluble agents).
bladder temp only accurate if
normal to high uop
esoph temp probe placement
distal (lower) third of esoph (otherwise trach gases affect it)
skin temp is usually within __ degrees of core temp
2
can you use rectal temp to detect MH?
no
L in full O2 tank
660
PSIG in full O2 tank
1900-2200
L in full Nitrous Oxide tank
1590
PSIG in full Nitrous Oxide tank
745
L in full CO2 tank
1590
PSIG in full CO2 tank
838
L in full Air tank
625
PSIG in full Air tank
1900
L in full Helium tank
500
PSIG in full Helium tank
1600
Cerebral blood flow affected by
Cerebral blood flow is directly related to body temperature, PaCO2 (within normal physiologic ranges), and extremes of MAPs (< 50 or >150 mm Hg). Cerebral blood flow is inversely related to PaO2 when less than 50 mm Hg. Cerebral blood flow remains unchanged within the autoregulatory range of MAPs (50-150 mm Hg) and with PaO2 >50 mm Hg.
digitalis effect on K
hyperkalemia
heparin effect on k
hyperkalemia
mannitol effect on k
hyperkalemia
pentamidine effect on k
hyperkalemia
triamterene effect on k
hyperkalemia
trimethoprim effect on k
hyperkalemia
ACE inhibitors effect on k
hyperkalemia
ARBs effect on k
hyperkalemia
non-selective beta blockers effect on k
hyperkalemia
NSAIDs effect on k
hyperkalemia
etomidate, midaz, propofol potentiate activity of what receptor
GABA
Ketamine mech of A
NMDA antagonist; NMDA is excitatory GLUTAMATE receptor
when use ANOVA
parametric (bell curve) continuous data between 3 or more groups
when use chi-squared
single variable discrete data
Wilcoxon-Mann-Whitney for single variable ordinal data (like ranked 1st, 2nd, 3rd, etc)
Risk of co2 absorbents Barium hydroxide Soda lime Calcium hydroxide Desiccated absorbents
Carbon dioxide absorbents containing barium hydroxide produce the most compound A and have the highest risk for fire production during sevoflurane administration. Soda lime, due to higher water content, has a reduced incidence of compound A and fire production. Calcium hydroxide absorbents, due to lower reactivity, have the lowest incidence of compound A and fire production. Desiccated absorbents absorb less CO2, produce more heat and carbon monoxide, and have an increased risk of compound A and fire production.
Laminar flow affected by gas density or viscosity?
Laminar flow is primarily affected by gas viscosity (Hagen-Poiseuille equation). The annular space towards the top of a conventional flowmeter is considered to be orificial. Turbulent flow, affected primarily by gas density (Graham’s law), is present around the flowmeter when the FGF is high.
Turbulent flow affected by density or viscosity?
Laminar flow is primarily affected by gas viscosity (Hagen-Poiseuille equation). The annular space towards the top of a conventional flowmeter is considered to be orificial. Turbulent flow, affected primarily by gas density (Graham’s law), is present around the flowmeter when the FGF is high.
Suggamadex is incompatible with what 3 drugs?
ondansetron, ranitidine, and verapamil
Suggammadex only approved to block what 2 drugs
Roc and vec
Unique LMA size ___ can fit what size ETT?
1.5 - 4 2 - 4.5 2.5 - 5 3 - 6 4 - 6 5 - 7 6 - 7
- 5 is always 5
- 5 is always 4
I-Gel LMA size—— ETT can fit
1 - 3 1.5 - 4 2 - 5 2.5 - 5 3 - 6 4 - 7 5 - 8
- 5 is always 5
- 5 is always 4
Pro deal LMA size —— ETT size
1 - 3.5 1.5 - 4 2 - 4.5 2.5 - 5 3 - 5 4 - 5 5- 6
- 5 is always 5
- 5 is always 4
Milrinone mechanism and effect
Milrinone is a selective PDE III inhibitor and decreases the hydrolysis of cyclic AMP.
increases contractility of the heart. Milrinone also causes vasodilatation and decreased afterload. Milrinone is often used as an inotropic medication following cardiopulmonary bypass, for pulmonary hypertension, and during acute CHF exacerbation. However, chronic milrinone treatment has been associated with increased mortality.
Dobutamine mechanism and effects
Dobutamine is a synthetic catecholamine which acts on beta-adrenergic receptors. This leads to an increase in cAMP via G-protein-coupled receptors (GPCR). Stimulation of beta-1 receptors causes an increase in heart rate and contractility, which increases CO. Dobutamine does have slight vasodilating properties, which can result in a decrease in systolic blood pressure and mean arterial pressure. In cardiogenic shock, dobutamine is a good choice of inotropic agent. The common problem with dobutamine is tachyarrhythmias.
Isoproterenol
Isoproterenol is a beta agonist medication, which increases heart rate. A slight increase in CO is seen as a result of the Treppe effect. Isoproterenol is often considered the drug of choice to increase heart rate in a denervated heart. A denervated heart cannot respond to antimuscarinic medications and needs direct agonism. Isoproterenol and epinephrine can provide direct beta agonism in these situations
Levosimendan
Levosimendan is a calcium sensitizing medication. Levosimendan increases cardiac sensitivity to calcium, thus increasing inotropy and CO. Levosimendan has a short half-life, but produces active metabolites with longer half-lives. Levosimendan is not currently available in the United States. Side-effects of levosimendan include tachyarrhythmias and hypotension.
Beta receptors and cAMP
Beta-adrenergic receptors use cAMP as a second messenger to increase phosphorylation of calcium and potassium channels in the cells. Increased levels of cAMP causes increased contractility (inotropy), heart rate (chronotropy), and conduction velocity (dromotropy). This leads to an increase in intracellular calcium and increases inotropy
Specificity
Specificity = TN / (TN+FP), the chance (%) to correctly rule in the disease or problem. Specificity “rules in” the disease.
The ideal experiment or test has a sensitivity and specificity of 1.0. Most “real” tests do not reach 1.0, but should be as close as possible. Some tests favor higher sensitivity while others favor higher specificity. A sensitive test rarely misses a condition, so a negative result should be reassuring. Most “screening” tests are highly sensitive. A highly specific test is unlikely to give a false positive result meaning that a positive result should be regarded as a true positive. A “confirmatory” test should be highly specific.
Sensitivity
Answer A: Sensitivity = TP / (TP+FN), the chance (%) to correctly detect the disease or problem. Sensitivity “rules out” the disease.
Negative predictive value
Answer D: Negative predictive value = TN / (TN+FN), the chance (%) that a negative test result means that the subject does not actually have the disease or problem
Positive predictive value
Answer C: Positive predictive value = TP / (TP+FP), the chance (%) that a positive test result means that the subject actually has the disease or problem
Effect of increased body water on NMBDs
Neuromuscular blocking agents are highly water-soluble due to quaternary amine structures and thus an increase in body water, such as with cirrhosis, CHF, or renal failure, results in decreased plasma concentration of neuromuscular blockers requiring an increase in intubating dose.
Describe renin pathway
A decrease in blood pressure stimulates the release of renin into the serum from the renal tubules. Renin converts angiotensinogen to angiotensin I, which is then converted to angiotensin II by ACE. Angiotensin II causes an increase in blood pressure by direct vasoconstriction, enhancing the sympathetic nervous system, and causing an increase of aldosterone.
NMBD with liver concerns
Rocuronium, vecuronium, and pancuronium will all have increased duration of action secondary to impaired hepatic metabolism (caveat: rocuronium is not metabolized but is cleared by the liver in the bile) and therefore maintenance dosing should be reduced and neuromuscular monitoring carefully followed.
Clearance of cisatracurium
Cisatracurium undergoes Hofmann elimination in the plasma and thus the duration of action is not affected by cirrhosis or renal disease. A breakdown product, laudanosine, is cleared by the liver but levels produced are insignificant clinically.
Ease of placement for a pulmonary artery catheter from easiest to most difficult is:
Ease of placement for a pulmonary artery catheter from easiest to most difficult is: right internal jugular > left subclavian > left internal jugular > right subclavian.
Solubility, from most to least, is
Solubility, from most to least, is halothane > isoflurane > sevoflurane > nitrous oxide > desflurane.
Signs of PRIS
Propofol infusion syndrome is a rare complication of prolonged, high-dose propofol administration. Signs may include metabolic lactic acidosis, cardiac failure, renal failure, rhabdomyolysis, hyperkalemia, hypertriglyceridemia, hepatomegaly, and pancreatitis.
Anaphylaxis is a Type ___ reaction and is ___ mediated.
Anaphylaxis is a Type I reaction and is IgE mediated.
A skin rash represents a cutaneous ___ mediated immune reaction.
A skin rash represents a cutaneous T cell mediated immune reaction.
A Type ___ reaction results in hemolytic anemia and is ___ mediated.
A Type II reaction results in hemolytic anemia and is IgG and IgM mediated.
A type ___ reaction represents serum sickness,
A type III reaction represents serum sickness,
a type ___ reaction is contact dermatitis.
a type IV reaction is contact dermatitis.
___ are responsible for the acute phase immune reaction to infection
IgM antibodies are responsible for the acute phase immune reaction to infection
A high-grade stenotic lesion along the ______ artery may result in atrioventricular (AV) nodal blockade.
A high-grade stenotic lesion along the posterior descending artery (PDA) may result in atrioventricular (AV) nodal blockade. This is due to the indirect blockage of the PDA’s AV nodal branch.
Laryngospasm management involves:
Laryngospasm management involves: 100% oxygen with positive pressure < 20 cm H2O, Larson maneuver (retromandibular notch jaw thrust), optional IV anesthetic, and last resort IV succinylcholine.
side effect of hetastarch
administration of hetastarch inhibits agonist-induced expression of glycoprotein IIb-IIIa complex availability on platelets. Thus, because of the decreased availability of the glycoprotein IIb-IIIa complex, platelets are not able to achieve the appropriate conformation to bind fibrinogen, which negatively affects platelet aggregation.
PEEP hemodynamic changes in normal patient…
in systolic heart failure patient…
PEEP application raises intrathoracic pressure, right ventricular afterload, decreases preload and can cause hypotension in the normovolemic or hypovolemic patient without heart failure. In patients with systolic heart failure, preload is excessive, thus PEEP preload effects are minimized but afterload is decreased with resultant improvement in cardiac output and a decrease in LVEDP.
minimal sedation
normal response to verbal stimulation, airway remains unaffected, spontaneous ventilation maintained, and cardiovascular function unaffected.
moderate sedation
(“Conscious Sedation”): purposeful response to verbal or tactile stimulation, no intervention required to maintain patent airway, adequate spontaneous ventilation, and cardiovascular function usually maintained.
deep sedation
purposeful response following repeated or painful stimulation, airway intervention may be required, spontaneous ventilation may be inadequate, and cardiovascular function usually maintained.
general anesthesia
unarousable even with painful stimulation, intervention on the airway often required, spontaneous ventilation is inadequate, and cardiovascular function may be impaired.
PCA pros and cons
Advantages of PCA compared with intermittent nurse-administered dosing of opioids are: decreased time spent by nursing, higher patient satisfaction, and superior analgesia. Disadvantages are increased opioid consumption and increased cost.
when give abx prophy for dental procedure re: endocarditis
Antibiotic prophylaxis with dental procedures is reasonable only for patients with cardiac conditions associated with the highest risk of adverse outcomes from endocarditis (also undergoing high-risk procedure), including:
1) Prosthetic cardiac valve or prosthetic material used in valve repair (A)
2) Previous endocarditis
3) Congenital heart disease (CHD) ONLY in the following categories:
- Unrepaired cyanotic congenital heart disease, including those with palliative shunts and conduits
- Completely repaired congenital heart disease with prosthetic material or device during the first six months after the procedure*
- Repaired congenital heart disease with residual defects at the site or adjacent to the site of a prosthetic patch or prosthetic device (which inhibit endothelialization)
4) Cardiac transplantation recipients with cardiac valvular disease
when give abx prophy for endocarditis with GI/GU procedures
Antibiotic prophylaxis solely to prevent IE is no longer recommended for patients who undergo a GI or GU tract procedure, including patients with the highest risk of adverse outcomes due to IE.
what kind of procedures is infective endocarditis abx ppx indicated with (if heart requirements are also met)
1) Dental (mucosal, gingival) procedures or
2) Respiratory tract (tonsillectomy, adenoidectomy, bronchoscopy with incision/biopsy) procedures or
3) Infected skin/musculoskeletal tissue procedures
phenytoin MoA
Phenytoin is an antiepileptic drug with antiarrhythmic properties mediated by blockade of voltage gated sodium channels.
lidocaine MoA
Lidocaine is the classic class Ib antiarrhythmic that phenytoin is also a member of. Class Ib antiarrhythmics bind voltage gated sodium channels and result in a decrease in the duration of the ventricular action potential. Because these drugs bind to and detach from the sodium channel rapidly and have greater affinity for the active and inactivated (but not resting) state, they are typically useful in tachyarrhythmias. These drugs also have minimal, if any, effect on the atrium and therefore are reserved for ventricular arrhythmias. Other drugs in this class include mexiletine and tocainide.
name 2 drugs that inhibit production of T4
which one does something else too?
Propylthiouracil and methimazole are both medications that can be used to inhibit the production of thyroid hormone (T4). In addition, propylthiouracil blocks the peripheral conversion of T4 to T3.
drug to destroy thyroid gland, and caveat
Radioactive iodine (iodine-131) can be given orally to either severely restrict or completely destroy the thyroid gland. Because iodine is picked up almost exclusively by the thyroid gland, and even more so by overactive thyroid cells, the effect of treatment is completely localized to the thyroid gland. One side effect of treatment is an initial period of a few days of increased hyperthyroid symptoms. This occurs because when the radioactive iodine destroys the thyroid cells, they can release thyroid hormone into the blood stream. For this reason, sometimes patients are pre-treated with thyrostatic medications such as methimazole, and/or they are given symptomatic treatment such as propranolol. Radioactive iodine treatment is contraindicated in breast-feeding and pregnancy. Commonly patients become hypothyroid after treatment, requiring supplemental thyroid hormone therapy.
law and formula regarding flow
The Poiseuille Law states that: Q = ΔP(π * radius4) / (8 * viscosity * length) Where: Q = flow, Δ = change in, P = pressure, π = 3.14159… (the mathematical constant).
duration of dual antiplatelet therapy with bare metal stent and drug eluting stent after PCI for stable ischemic heart disease
According to the 2016 ACC/AHA guidelines, patients undergoing PCI for stable ischemic heart disease should receive dual antiplatelet therapy for at least one month after BMS and at least six months after DES.
duration of dual antiplatelet therapy after PCI for ACS
In patients undergoing PCI for acute coronary syndrome, the recommendation is to continue dual antiplatelet therapy for at least 12 months, irrespective of the type of stent, (but it is reasonable to discontinue after 6 months in patients at high risk of severe bleeding, e.g. major intracranial surgery).
how much does hyperventilation affect CBF
Hyperventilation leads to decreased CBF by decreasing PaCO2. CBF changes 1-2 mL/100 g/min per every 1 mmHg change in PaCO2
Phase 1 block. What is it? twitch height? tetanus? TOF ratio? What does neostigmine do to it? What do NMBDs do to it?
Standard intubating doses of succinylcholine generally create a phase I depolarizing block characterized by decreased twitch height, sustained tetanus, and a TOF ratio > 0.7. Neostigmine will potentiate a phase I block while a nondepolarizing NMBD will antagonize the block. Prolonged infusions or large doses of succinylcholine create a phase II nondepolarizing block, which is similar to that created by nondepolarizing NMBDs.
restrictive disease: FVC FEV1 FEV1/FVC FEF25%-75% FRC TLC
FVC ↓↓↓ FEV1 ↓↓↓ FEV1/FVC Normal FEF25-75% Normal FRC ↓↓↓ TLC ↓↓↓
obstructive disease: FVC FEV1 FEV1/FVC FEF25%-75% FRC TLC
FVC Normal or slightly ↑ FEV1 ↓↓↓ FEV1/FVC ↓↓↓ FEF25-75% ↓↓↓ FRC Normal or ↑ TLC Normal or ↑
Treatment options for EPS or acute dystonic reactions from dopamine receptor antagonists include:
Treatment options for EPS or acute dystonic reactions from dopamine receptor antagonists include anticholinergics (preferred), benzodiazepines, beta-blockers, antihistamines, dopamine agonists, and alpha-adrenergic agonists. Commonly used anticholinergic agents are benztropine, diphenhydramine, and trihexyphenidyl.
why COPD patient hypercapneic after O2 administration
Hypercapnia following administration of oxygen to a patient with chronic obstructive pulmonary disease is primarily due to ventilation-perfusion mismatching, driven by inhibition of hypoxic pulmonary vasoconstriction.
MELD score components
MELD: “I Crush Several Beers Daily” for INR, creatinine, sodium, bilirubin, dialysis
Childs-Pugh: “Pour Another Beer At Eleven” for PT, Ascites, Bilirubin, Albumin, Encephalopathy
Childs-Pugh score components
MELD: “I Crush Several Beers Daily” for INR, creatinine, sodium, bilirubin, dialysis
Childs-Pugh: “Pour Another Beer At Eleven” for PT, Ascites, Bilirubin, Albumin, Encephalopathy
midaz metabolites
Midazolam is metabolized to active forms called hydroxymidazolams, which have up to 30% the potency of the primary drug.
biotransformation of midaz and diazepam
Midazolam and diazepam undergo hepatic oxidation reduction
lorazepam biotransformation
Lorazepam has five metabolites but primarily undergoes glucuronide conjugation and, because of this, is less affected by age and liver disease
oxazepam biotransformation
Oxazepam is the other benzodiazepine that undergoes only glucuronidation, making it useful in patients with liver disease.
internal branch of SLN
The internal branch of the superior laryngeal nerve (SLN) provides sensation to the entire larynx above the glottis. Laryngospasm can result from stimulation of this nerve.
TrueLearn Insight : A mnemonic to differentiate the SLN branches is “SIME” for sensory = internal, motor = external.
glossopharyngeal nerve
The glossopharyngeal nerve (CN IX) does not innervate the larynx. It provides sensation to the pharynx, middle ear, posterior one-third of the tongue (including taste buds), and the carotid body and sinus. Motor branches from CN IX innervate the parotid salivary gland, the glands of the posterior tongue, and the stylopharyngeus muscle (which dilates the pharynx during swallowing).
recurrent laryngeal nerve
The RLN adducts and abducts the vocal cords and provides motor function to all of the intrinsic muscles of the larynx except the cricothyroid. The RLN also provides sensation to the larynx from the glottis and below. Stimulation can lead to laryngospasm because it is part of the vagus nerve, however the RLN is not considered the afferent limb that mediates laryngospasm.
external branch SLN
The external branch of the SLN innervates the cricothyroid muscle, which tenses and adducts the vocal cords.
mechanism of cyanide toxicity
Cyanide toxicity does not lead to a decreased oxygen delivery. Instead, it affects the way that tissues can use oxygen. Cyanide is a toxin that inhibits cytochrome oxidase, leading to interference with oxidative metabolism and cellular use of oxygen. The delivery of oxygen usually increases in the acute phase of toxicity as the body tries to compensate for the cells’ inability to use the oxygen.
oxygen content equation
OXYGEN CONTENT:
CaO2 = SaO2 x Hgb x 1.34 + (PaO2 x 0.003)
CaO2 = arterial oxygen content (mL/dL)
SaO2 = arterial oxygen saturation (should be 0.93-1)
Hgb = hemoglobin concentration (g/dL)
PaO2 = arterial partial pressure of oxygen (mm Hg)
1.34 is used because it is the oxygen carrying capacity of hemoglobin and 0.003 is used as it is the solubility coefficient of oxygen in plasma
oxygen delivery equation
OXYGEN DELIVERY:
DO2 = CaO2 x CO x 10
CaO2 = arterial oxygen content CO = cardiac output (which is heart rate x stroke volume)
what drug causes cyanide poisoning
Cyanide toxicity can occur with the use of sodium nitroprusside. Sodium nitroprusside is used as a vasodilator, however its metabolism results in the release of cyanide ions. Usually the cyanide ions are metabolized and no side effects occur. When higher doses of nitroprusside are used for prolonged periods of time, cyanide can build up and toxicity occurs. Cyanide toxicity is characterized by metabolic acidosis and cardiac arrhythmias. Treatment is with hydroxocobalamin.
treatment of cyanide toxicity
Cyanide toxicity can occur with the use of sodium nitroprusside. Sodium nitroprusside is used as a vasodilator, however its metabolism results in the release of cyanide ions. Usually the cyanide ions are metabolized and no side effects occur. When higher doses of nitroprusside are used for prolonged periods of time, cyanide can build up and toxicity occurs. Cyanide toxicity is characterized by metabolic acidosis and cardiac arrhythmias. Treatment is with hydroxocobalamin.
acoustic impedance is determined by…
Acoustic impedance is the product of the density of a medium and the propagation speed of sound through that medium. Ultrasound reflections that occur at the interface of different mediums are due to the changes in acoustic impedance. Since propagation speed changes slightly between biological mediums, acoustic impedance is primarily dependent upon density.
drug of choice to treat delirium caused by scop patch
Physostigmine is an anticholinesterase with a tertiary amine structure that can be used as a treatment for central anticholinergic syndrome. (scop crosses blood brain barrier and so does physostigmine)
how does the Tensilon test work
Edrophonium (by the so-called “Tensilon test”) is used to differentiate myasthenia gravis (MG) from cholinergic crisis and Lambert-Eaton myasthenic syndrome (LEMS). In myasthenia gravis, the body produces autoantibodies which block, inhibit or destroy nicotinic acetylcholine receptors in the neuromuscular junction. Edrophonium, an effective acetylcholinesterase inhibitor, will reduce the muscle weakness by blocking the enzymatic effect of acetylcholinesterase enzymes, prolonging the presence of acetylcholine in the synaptic cleft. Edrophonium is ineffective at crossing the blood brain barrier and thus is not used for management of scopolamine-induced delirium.
ESRD effects: Hgb Ca K Mg lipids BP Phosphate PTH Uremia Na
Changes seen in end-stage renal disease include:
- Anemia
- Hypocalcemia
- Hyperkalemia
- Hypermagnesemia
- Hyperlipidemia
- Hypertension
- Hyperphosphatemia
- Secondary hyperparathyroidism
- Uremic bleeding diathesis
- No effect on Na
bronchospasm first line therapy
During acute bronchospasm under general anesthesia, administration of a selective beta2-agonist such as albuterol is first line therapy.
Context-sensitive half-time (in minutes) after 3 and 8 hour infusion of: Fentanyl Propofol Alfentanil Remifentanil
Fent: 100 and 275
Prop 15 and 30ish
Alfentanil 50 and 50
Remi 10 and 10
case-control study
In a case-control study, groups of subjects are compared with respect to the effect of a particular intervention. One group has a particular outcome of interest (cases) while another group does not have the outcome of interest (controls). The groups are compared to see if the particular intervention made a difference between the two groups. In a case-control study, it is very important to recognize that the separation of subjects into case and control groups occurs AFTER the intervention that is being studied occurred. Based on this reason, a case-control study is sometimes called a retrospective study (though the term is not entirely accurate since a case-control study can be planned in advance, i.e. “prospectively”). Compare this to a cohort study, below.
cohort study
In a cohort study, like in a case-control study, groups (“cohorts”) of subjects are compared with respect to the effect of a particular intervention. The important distinction between the two study types is that in a cohort study, the assignment of a subject to one group or the other occurs BEFORE the intervention that is being studied occurs. Groups should be as similar as possible (i.e. the two groups are matched in terms of as many other variables as possible) aside from the particular intervention under investigation, and the two groups are monitored before and after the intervention. A cohort study is sometimes called a prospective study (though the term is not entirely accurate since the data analysis occurs after the intervention and monitoring, i.e. “retrospectively”). Cohort studies can also be thought of as a randomized controlled trial without the randomization.
Name factors that increase MAC requirements for anesthetic gases
Hyperthermia, hypernatremia, chronic ethanol abuse, and increased central neurotransmitter levels (e.g. MAOIs, amphetamine, cocaine, ephedrine, and levodopa use) increase MAC requirements for anesthetic agents.
how is cisatracurium cleared
Hoffman
neostigmine. what percent cleared by kidney?
50%
rocuronium cleared by
70% hepatic and 10-30% renal; no active metabolites
vecuronium cleared by
50-60% hepatic and 25% renal
what test to compare 2 groups of ordinal or non-parametric (parametric means normal dist or bell curve) interval data?
Wilcoxon-Mann-Whitney test
what test to compare MORE THAN 2 (not matched) groups of ordinal or non-parametric (parametric means normal dist or bell curve) interval data?
Kruskall-Wallis
what test to compare 2 PAIRED groups of ordinal or non-parametric (parametric means normal dist or bell curve) interval data?
wilcoxon-signed rank test
what test to compare MORE THAN 2 MATCHED groups of ordinal or non-parametric (parametric means normal dist or bell curve) interval data?
Friedman
H2 blockers onset time, duraton
Histamine receptor antagonists are used to increase the pH of gastric acid in patients at risk of aspiration. Following oral administration, effects can be seen in 1 hour. Following intravenous administration, effects are seen in under 30 minutes for cimetidine and famotidine but take up to 1 hour for ranitidine.
But also:
The onset of action of cimetidine is approximately 60-90 minutes while that of newer histamine H2 receptor antagonists is approximately one hour. Ranitidine has a shorter onset of action, longer duration of action, and less side effects than cimetidine. Famotidine has a longer half-life than cimetidine or ranitidine.
PPI onset time and duration
Proton pump inhibitors take 2-4 hours (D) to initial effect when administered orally. Peak response may take up to 5 days. Proton pump inhibitors (PPI) act by binding to hydrogen potassium pumps. PPIs cause a permanent inhibition of proton pumps. Synthesis of new pumps takes about 24 hours, which explains the duration of action of PPI medications.
Random facts about substance abuse in anesthesia
1) 50% are < 35 years old
2) Residents are overrepresented
3) Many are Alpha Omega Alpha members
4) 33-50% are polydrug abusers
5) For 76-90%, opioids (e.g., fentanyl and sufentanil) are the abuse drug class of choice
6) 33% have a family history of addiction
7) 65% are associated with academic departments
How do volatile anesthetics affect neuromuscular blockade?
Volatile anesthetics potentiate neuromuscular blockade by DECREASING sensitivity of the postjunctional membrane to depolarization and INCREASING skeletal muscle blood flow (brings more drug to the muscles) which both augment neuromuscular blockade. In addition, potentiation of neuromuscular blockade occurs by depression of upper motor neurons.
FENA cutoff for pre-renal
Fractional excretion of sodium is a useful tool in helping to distinguish the cause of acute kidney injury. In general, a FENA < 1% indicates a prerenal cause such as hypovolemia. Greater than 1% points toward ATN or another intrinsic cause.
prerenal urine osmolality
greater than 500
prerenal urine sodium
less than 10
prerenal BUN:Cr ratio
greater than 20
formula for SVR
SVR = [80 * (MAP – RAP)] ÷ CO
= [80 * (100 – 5)] ÷ 5
= 1520 dynes * sec/cm^5
Where:
MAP = mean arterial pressure (mm Hg)
RAP = right atrial pressure (mm Hg), central venous pressure is commonly substituted for RAP
CO = cardiac output (L/min)
80 = conversion factor which changes mm Hg/L/min (Woods unit) to dynes * sec/cm^5
formula for MAP
MAP = [(1/3) * systolic pressure] + [(2/3) * diastolic pressure]
= [(1/3) * 120 mm Hg] + [(2/3) * 90 mm Hg]
= 100 mm Hg
MPAP formula
mean pulmonary arterial pressure (MPAP) must be calculated since it is not given directly:
MPAP = [(1/3) * systolic pressure] + [(2/3) * diastolic pressure]
= [(1/3) * 24 mm Hg] + [(2/3) * 12 mm Hg]
= 16 mm Hg
PVR formula
PVR = [80 * (MPAP – PAOP)] ÷ CO
= [80 * (16 – 8)] ÷ 5
= 128 dynes * sec/cm^5
Where:
MPAP = mean pulmonary arterial pressure (mm Hg)
PAOP = pulmonary artery occlusion pressure or pulmonary capillary wedge pressure (mm Hg)
CO = cardiac output (L/min)
80 = conversion factor which changes mm Hg/L/min (Woods unit) to dynes * sec/cm^5
Smoking cessation benefits and timeline
Most benefits of smoking cessation occur after 2-3 months (reduced sputum production, improved ciliary function, improved closing volume, and increased FEF25-75%). However, a decrease in carboxyhemoglobin concentrations and the resultant rightward shift of the oxyhemoglobin dissociation curve occur in as little as 48 hours after smoking cessation.
O2 consumption in adult
3-4mL/kg/min
FRC in adult
30mL/kg
Minutes until hypoxemia
Minutes until hypoxemia = [FRC (ml) ÷ O2 consumption (mL/min)] * %O2 in FRC.
reduction in FRC going from upright to supine
10-15%
reduction in FRC under GA
10%
Nitrous oxide deleterious effects
Nitrous oxide is associated with megaloblastic changes and agranulocytosis due to its ability to decrease the activity of vitamin B12-dependent enzymes.
Nitrous oxide inhibits the vitamin B12-dependent enzymes, methionine synthetase and thymidylate synthetase. This may lead to subclinical problems in relatively healthy patients, but may cause neurologic and hematologic sequelae in critically ill and vitamin B12-deficient patients
Nitric oxide
Inhaled nitric oxide promotes increased blood flow only to alveolar units that are ventilated to improve V/Q matching.
Why FiO2 not great in ARDS?
Oxygen therapy is of limited value with large intrapulmonary shunts due to limitation of gas exchange and requires alternative therapies to improve V/Q matching.
Milrinone:
effect on intracellular cAMP
effect on Ca stores
What is an inodilator?
Milrinone, a PDE III inhibitor, increases cardiac inotropy and causes peripheral and pulmonary vasodilation via increased intracellular cAMP levels and calcium stores. Milrinone is also referred to as an inodilator for these reasons. The effects of an inodilator may be illustrated on the myocardial P-V loop. These include a reduction in the slope of the diastolic filling phase, LVEDP, AoDP (mild), AoSP, LVESV, and the LVESP. There is also an increase in lusitropy (ventricular relaxation), SV, CPP, and myocardial contractility.
Drugs that increase K
trimethoprim, digitalis, heparin, mannitol, pentamidine, triamterene, ACE-i, ARBs, non-selective beta blockers, NSAIDs, amiloride
hypertensive hep Mannitol digging, NSAID “Am Tri pent”
Order CO2 absorbents from least risk to greatest risk
risk of what 2 things?
Carbon dioxide absorbents containing barium hydroxide produce the most compound A and have the highest risk for fire production during sevoflurane administration. Soda lime, due to higher water content, has a reduced incidence of compound A and fire production. Calcium hydroxide absorbents, due to lower reactivity, have the lowest incidence of compound A and fire production. Desiccated absorbents absorb less CO2, produce more heat and carbon monoxide, and have an increased risk of compound A and fire production.
First-stage Oxygen regulator
The first-stage regulator will shut off the lower pressure oxygen cylinder tanks when the higher-pressure oxygen pipeline is sensed.
Second-stage oxygen regulator
The second-stage regulator, if present, will decrease pressure to slightly above atmospheric to ensure smooth constant flow of gases.
Risk factors for post op cognitive dysfunction
Risk factors for POCD are advancing age, lower educational level, and a history of previous cerebral vascular accident with no residual impairment.
First thing in case of power failure
If a power failure occurs in the operating room the provider should switch to the red plate electrical supply system, which is the emergency power system in the United States. Nearly all life-support devices, including the anesthesia machine, have battery backup capability and will continue to function.
What cause hemodynamic changes during CEA?
Hemodynamic changes during CEA are common and are related to surgical manipulation, denervation, and impaired sensitivity of the carotid sinus baroreceptors. Stimulation of baroreceptors results in increased parasympathetic discharge with decreased sympathetic discharge. This leads to hypotension and bradycardia, which can potentially be prevented by local anesthetic infiltration.
TrueLearn Insight : Think “sinus pressure” to help differentiate the roles of the carotid sinus and carotid body.
Carotid body is chemoreceptor or mechanoreceptor?
The carotid body is a chemoreceptor, not a mechanoreceptor, and does not control blood pressure. Is just a sensor
Effect of lidocaine infiltration at carotid sinus
Lidocaine infiltration causes inhibition of baroreceptor output from the carotid sinus and would result in hypertension and tachycardia.
Lambert-Eaton mechanism of weakness
Presynaptic calcium channel destruction is the mechanism of the weakness associated with Lambert-Eaton syndrome
succ MoA
Succinylcholine, a depolarizing neuromuscular blocker, works as an acetylcholine receptor agonist.
Static respiratory system compliance formula
CS = VT ÷ (PPL – PEEP)
Where: CS is static compliance, VT is tidal volume, and PPL is plateau pressure.
The static compliance of the respiratory system indicates the “stiffness” of the respiratory system, which includes the lungs and chest wall. It is determined at the end of inspiration when there is no airflow, hence “static.”
Compliance formula
compliance is the change in volume divided by the change in pressure of a system (C = ΔV/ΔP)
Dynamic respiratory system compliance
CS = VT ÷ (Ppeak – PEEP)
Where: CS is static compliance, VT is tidal volume, and Ppeak is peak pressure.
Formula for elastance
Elastance is the inverse of compliance: E = ΔP/ΔV.
Phase 1 metabolism
Phase I involves modifying the drug through oxidation, reduction, or hydrolysis. These reactions typically inactivate the drug
Phase II metabolism
Phase II involves conjugation, where a molecule (glucuronic acid, sulfate) is added to the drug to make it more easily excreted from the kidneys and liver.
CYP450: which phase of metabolism?
What is the mechanism?
Cytochrome p450 is the most important enzyme system in phase I and catalyzes the oxidation of many drugs.
What PONV drugs can cause extrapyramidal sx?
Although often effective for treatment of postoperative nausea and vomiting (PONV), antidopaminergic drugs (e.g. droperidol, metoclopramide, prochlorperazine) can cause extrapyramidal symptoms (EPS) by altering the cholinergic-dopaminergic balance in the central nervous system, notably in the basal ganglia. Extrapyramidal side effects include acute dystonias (abnormal movement or posturing due to involuntary/sustained muscle contractions), akathisia (restlessness and need to be in constant motion), and tardive dyskinesia (involuntary repetitive or purposeless movements).
Diphenhydramine
Diphenhydramine has antihistamine (H1) and anticholinergic activity, inhibits serotonin reuptake, potentiates opioid-induced analgesia, and may have local anesthetic-like properties (intracellular sodium channel blocker).
3 drugs associated with histamine release. Which can increase bronchospasm and which is safe in asthma?
Histamine release associated with morphine and atracurium can potentially induce bronchospasm in patients with reactive airway disease. Succinylcholine is also associated with histamine release, but there is no evidence to suggest an increased incidence of bronchoconstriction with its use. It is therefore considered safe to use in patients with asthma.
Nasal polyps and asthma
There is a subset of patients that have asthma triggered by aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs). This occurs in approximately 8-20% of adult patients with asthma. Nasal polyps are commonly seen in this patient population, but it is also common for patients without aspirin sensitivity to have nasal polyps. It would be safest to avoid nonsteroidal drugs such as ketorolac in a known asthmatic with nasal polyps.
Bronchospasm treatment if cannot ventilate
Intravenous epinephrine and subcutaneous terbutaline both have very strong β2-agonist activity and will be helpful in this emergent acute setting. Intravenous epinephrine is also a mast cell stabilizer and works to reduce histamine release and inflammation within the bronchial tree.
Intravenous anesthetics, such as ketamine and propofol, can be used to rapidly deepen the level of anesthesia and alleviate bronchospasm.
Deepening the inhaled anesthetic agent, inhaled β2-agonists, and inhaled anticholinergics are helpful for the treatment of bronchospasm, but the inability to ventilate makes most of them ineffective in this emergent setting.
chronic resp acidosis compensation
pH nearly normalizes and HCO3- concentrations increase 4-5 mEq/L per 10mmHg sustained increase in PaCO2
acute resp acidosis compensation
acute respiratory acidosis should demonstrate a pH decrease of 0.05 and a HCO3- increase of 1 mEq/L per acute 10 mm Hg increase in PaCO2.
chronic resp alkalosis compensation
If the respiratory alkalosis becomes chronic, pH nearly normalizes and HCO3- decreases 5 to 6 mEq/L per 10 mm Hg sustained decrease in PaCO2.
acute resp alkalosis compensation
A patient experiencing acute respiratory alkalosis should demonstrate a pH increase of 0.10 and a HCO3- decrease of 2 mEq/L per acute 10 mm Hg decrease in PaCO2.
how many liters left in nitrous oxide tank when pressure starts to fall
253 liters (~16% tank volume); it then drops proportionally to the amount of remaining nitrous oxide
hypothermia effect on EtCO2
decrease EtCO2
hyperthyroid effect on EtCO2
increase EtCO2
What prevents micro shock in OR
The equipment ground wire is the most reliable means to prevent microshock. The ground fault interrupter can prevent macroshocks, but does not reliably prevent microshocks.
What is the GFCI?
A ground fault circuit interrupter (GFCI) is a device placed to monitor current imbalance in grounded circuits. The GFCI monitors current flow on both the “hot” and “neutral” wires, which should be equal. The GFCI breaks current flow if there is a current imbalance between the two, suggesting an alternate grounds. This is not the best method for prevention of microshock as its threshold value is closer to 5 milliamps, which is several fold above that required for microshock.
What receptors stim lipolysis?
What receptors inhibit lipolysis?
Men or women more sensitive?
In general, lipolysis is increased by beta-2 and beta-3 adrenergic stimulation but is inhibited by alpha-2 stimulation. Women are more sensitive to the lipolytic actions of catecholamines when compared to men.
x mechanism and effects
Glucagon activates adenyl cyclase to increase cyclic AMP levels. Glucagon increases cardiac index, mean arterial pressure, and ventricular contractility.
Glucagon contraindications
Glucagon in contraindicated in pheochromocytoma due to the risk for hyperglycemia and severe hypertension. It is also contraindicated in insulinoma due to the risk of severe hypoglycemia.
4 most common causes of atlanto-axial instability
The most common causes of atlantoaxial instability include trauma, achondroplasia, Down syndrome, and rheumatoid arthritis.
Which circuits have no valves
Fresh gas flow needs to be at least…
Mapleson D, E and F circuits have no valves: if a circuit has no valves, it can result in rebreathing of exhaled gases if fresh gas flows are not high enough. Use of capnometry to determine if this is occurring can help guide the fresh gas flow rate. General rule – fresh gas flow should be at least 2.5 times the minute ventilation to decrease the risk of rebreathing.
Which circuit is a t piece
Mapleson E is considered a T-piece.
Which mapleson circuits can be used with a ventilator
Mapleson D and F circuits can be used with mechanical ventilation by removing the reservoir bag and connecting a ventilator
How is esmolol metabolized
Esmolol is a β1-selective short acting (t1/2 = 9 min) agent that is rapidly metabolized by red blood cell (RBC) esterases and minimally hydrolyzed by pseudocholinesterase.
Which are the cardioselective beta blockers
The cardioselective (β1) blockers may be remembered with the mnemonic “BEAM” (Bisoprolol, Esmolol, Atenolol, and Metoprolol)
highly unlikely to induce bronchospasm in patients with preexisting reactive airway disease.
Propranolol
Propranolol is non-selective and inhibits β1 and β2 receptors while labetalol is a β1, β2, and α-1 receptor blocker.
Labetalol
Think “laβetαlol.” The ratio of relative α:β potency of IV labetalol is approximately 1:7 whereas PO labetalol is 1:3. The nature of this drug can be seen intraoperatively when labetalol administration results in decreased blood pressure without baroreceptor-triggered reflex tachycardia (as can be seen with pure vasodilating agents). Carvedilol is the only other commonly used β-blocker with α-antagonism; it is administered orally.
Atenolol metabolism
Atenolol is only available in oral form and is the only β-blocker listed that is primarily cleared by the kidneys.
The mnemonic “ATNolol” may be used to remember that the drug undergoes renal metabolism. Recall ATN = acute tubular necrosis, which affects the kidneys.
Labetalol metabolism
Labetalol and propranolol are metabolized via hepatic clearance
Propranolol metabolism
Labetalol and propranolol are metabolized via hepatic clearance
Metoprolol metabolism
Metoprolol is metabolized in the liver.
Obesity changes lung volumes
Lung volumes: obesity is characterized by a very marked decrease in expiratory reserve volume. In the presence of well-preserved residual volume, this is manifested as a reduction in functional residual capacity (FRC). Total lung capacity (TLC) is also reduced, but only modestly, thus inspiratory capacity (defined as TLC-FRC) is increased.
Contrast induced nephropathy prevention
Adequate fluid hydration is the most effective form of renal protection against CIN.
Acetaminophen toxicity treatment
Treatment of acetaminophen toxicity primarily centers on the administration of N-acetylcysteine (NAC). When administered early, NAC provides cysteine for the replenishment and maintenance of hepatic glutathione stores which enhances the elimination pathway and may reduce the hepatic toxicity of acetaminophen
Leftward shift in ventilatory response curve
Factors that cause a leftward shift and an increased slope of a carbon dioxide ventilatory response curve include arterial hypoxemia, metabolic acidemia, surgical stimuli, and certain CNS pathologies. Factors that cause a rightward shift and a reduced slope of the curve include opioids, barbiturates, and sedative-hypnotic drugs. Volatile anesthetics ≤1 MAC cause a rightward, parallel shift of the VRC.
Causes of rightward shift in ventilatory response curve
Factors that cause a leftward shift and an increased slope of a carbon dioxide ventilatory response curve include arterial hypoxemia, metabolic acidemia, surgical stimuli, and certain CNS pathologies. Factors that cause a rightward shift and a reduced slope of the curve include opioids, barbiturates, and sedative-hypnotic drugs. Volatile anesthetics ≤1 MAC cause a rightward, parallel shift of the VRC.
0.25%=
0.25g/100mL
or
2.5mg/mL
Carbon dioxide is transported in the blood as what 3 ways
Carbon dioxide is transported in the blood as dissolved CO2, bicarbonate, and carbamino compounds.
Laryngospasm innervation
Laryngospasm is a reflex that occurs when the internal branch of the superior laryngeal nerve is stimulated, causing a reflex closure of the vocal cords with motor innervation by the recurrent laryngeal nerve.
Benefits of leukoreduction
Leukoreduction is the process of depleting donor blood products of leukocytes in an effort to reduce immunosuppression associated with blood product transfusion. Confirmed benefits of leukoreduction include decreased transmission of CMV, decreased inflammatory response, decreased febrile reactions to packed red blood cell (PRBC) transfusions, and reduced inflammatory mediator accumulation during storage.
ED95
In general pharmacology, ED95 refers to the effective dose needed to get the desired effect for 95% of the population. Unfortunately, this term has a different meaning specifically for neuromuscular blocking agents. For these agents, ED95 refers to the median dose required to achieve a 95% reduction in the maximal twitch response from baseline, in 50% of the population.
Acute hemolytic transfusion reaction
Acute hemolytic transfusion reaction is due to ABO incompatibility. This can be fatal and is most often due to clerical error. Symptoms are variable and are related to the amount of incompatible blood transfused. Classically, fever, chills, chest pain, and nausea are seen. Under anesthesia many of these symptoms are masked and the only signs may be hemoglobinuria, bleeding diathesis, or hypotension.
Febrile transfusion reaction caused by
Febrile transfusion reactions are due to donor cytokines and antibodies to leukocyte antigens reacting to recipient leukocytes. Symptoms include fever, chills, headaches, myalgias, nausea, and nonproductive cough. They develop within a few hours of transfusion and the risk is 1 in 8 transfusions.
GVHD caused by…
Graft versus host disease (GVHD) is due to viable lymphocytes in donor blood reacting against recipient’s tissues. The recipient is unable to reject the donor lymphocytes because of immunodeficiency or immunosuppression. Symptoms include rash, fever, cytopenia, liver dysfunction, and diarrhea 3-4 weeks after the transfusion. Irradiation of donor blood components can help decrease the risk.
Delayed hemolytic transfusion reaction caused by
Delayed hemolytic transfusion reactions (DHTR) are also referred to as immune extravascular reactions. Hemolytic transfusion reactions can be defined as acute or delayed. Both are the result of recipient antibody and complement attack on donor cells. The target and concentration of recipient antibodies differentiates acute from delayed hemolytic transfusion reactions. In contrast to acute hemolytic transfusion reactions which are almost always due to ABO incompatibility, DHTRs are typically secondary to antibodies associated with the Rhesus (Rh), Kidd, or Kell systems (or other “minor” antigens).
Clinical risk factors for coronary disease include:
Clinical risk factors for coronary disease include:
- A history of ischemic heart disease
- Congestive heart failure
- History of stroke
- Diabetes
- Chronic kidney disease
Perioperative beta blocker guidelines
ACC/AHA 2014 guidelines recommend that patients on beta-blockers should have them continued through the perioperative period. Patients with 3 or more risk factors for coronary artery disease may also benefit from beta-blocker therapy preoperatively.
Do not start day of surgery
The most common and reliable sign of cyanide toxicity and mechanism
The most common and reliable sign of cyanide toxicity is an anion gap metabolic acidosis.
Cyanide primarily causes toxicity by impairing cellular aerobic respiration. The cyanide ion (CN-) binds to the ferric ion (Fe3+) in mitochondrial cytochrome-c oxidase, inhibiting the final stage of the electron transport chain. Depletion of cellular ATP and the lactic acid produced by anaerobic metabolism can lead to profound acidosis.
Which hormones are decreased during stress response?
T3
T4
GRH
(Insulin and TSH could go up or down)
The standard error of the mean (SEM) can be calculated by
The standard error of the mean (SEM) can be calculated by dividing the standard deviation (SD) by the square root of the sample size (n).
SEM = SD / sqrt(n)
Why epinephrine in v-fib?
Epinephrine produces beneficial effects during cardiac arrest primarily because of alpha-receptor mediated vasoconstrictor properties.
The vasoconstriction will cause an increase in coronary and cerebral perfusion pressure during cardiopulmonary resuscitation. The beta-mediated increase in chronotropy, dromotropy, and inotropy may actually cause an increase in myocardial work and subendocardial perfusion, thus they are not the reasons epinephrine is used.
How long wait after MI for noncardiac surgery?
After an MI wait 14 days after balloon angioplasty, 30 days after BMS, 60 days if no coronary intervention, and 180 days after DES for elective noncardiac surgery.
ACE-I contraindications
Angiotensin converting enzyme inhibitors (ACE-I) are contraindicated in renal artery stenosis (RAS), ACE-I allergy, pregnancy (teratogenic), and angioedema.
List NMDA receptor antagonists
Multiple medications commonly used perioperatively function as NMDA receptor antagonists. Examples include, but are not limited to: ketamine, magnesium sulfate, nitrous oxide, and certain opioids including methadone and tramadol.
Primary hyperthyroidism is characterized by what lab values
Primary hyperthyroidism is characterized by elevated T3, T4 (free and total), and thyroid hormone binding ratio, and a low or normal TSH.
rate of rise of the fractional concentration of inspired anesthetic.
The rate of rise of FI initially follows first order kinetics. It is directly related to the concentration of anesthetic agent being administered and the fresh gas flow; it is inversely related to the volume of the circuit.
Muscarinic receptors
The muscarinic receptors are found at the peripheral target organs. Stimulation will cause bradycardia, bronchoconstriction, miosis, salivation, gastrointestinal hypermotility and increased gastric acid secretion.
Risk factors and protective factors for anesthesiologists substance abuse
Risk factors in an anesthesiologist’s work/social life include a negative work atmosphere and low expectations of employees. Protective work/social factors include a caring and supportive climate with appropriately high and attainable expectations. Additionally, clear standards and rules with participation in important tasks and decisions are protective factors against substance use disorders.
Risks/side effects of spinal
Spinal anesthesia is associated with an incidence of PDPH as high as 25%. Other common complications or side effects include (unopposed parasympathetic stimulation from sympathectomy) increased gastrointestinal secretions and mobility, increased ventilatory response to hypercapnia, hypothermia from peripheral vasodilation, and a transient decrease in hearing ability.
Delta receptor
Delta receptor: analgesia, antidepressant, physical dependence
delta airlines: not depressed because high in the sky but you depend on the plane
Kappa receptor
Kappa receptor: analgesia, dysphoria, miosis, sedation
you get capped: pupils shrink, you feel crappy, you pass out
Mu receptor
Mu receptor: analgesia, physical dependence, respiratory depression, miosis, euphoria, decreased gastrointestinal motility
Mu (you) make me feel happy and take my breath away and make me hold in farts
Tramadol
Tramadol is a synthetic opioid analgesic which binds weakly to the opioid mu receptors. It also inhibits neuronal reuptake of norepinephrine and serotonin which is thought to mediate some of the analgesic effects.
Normal pulmonary wedge pressure
Normal pulmonary wedge pressure is 6-12 mmHg; elevated pressures are seen in congestive heart failure
Treatment for TRALI
Treatment for TRALI is supportive and starts with intravenous fluids and/or vasopressors.
Lung protective ventilation strategies using low tidal volumes, PEEP, permissive hypercapnia, and supplemental oxygen are effective TRALI treatment modalities.
Diuretics and corticosteroids are not recommended.
list common vesicants
Diazepam, phenytoin, promethazine, and thiopental are vesicants. Extravasation of each of these medications has been associated with severe local tissue necrosis, gangrene, or amputation.
Laboratory Findings Suggestive of AHTR Coombs Bilirubin Haptoglobin Hemoglobin (urine) LDH Urobilinogen Platelets PT/INR aPTT Fibrinogen Fibrin degradation products Creatinine BUN
Coombs positive Bilirubin ↑ (both direct and indirect) Haptoglobin ↓ Hemoglobin (urine) ↑ LDH ↑ Urobilinogen ↑ Platelets ↓ (in DIC) PT/INR ↑ (in DIC) aPTT ↑ (in DIC) Fibrinogen ↓ (in DIC) Fibrin degradation products ↑ (in DIC) Creatinine ↑ BUN ↑
FiO2 of simple face mask at 5-10 L/min
35-50%
FiO2 of nasal cannula
25-40% with flow rates up to 6L/min
FiO2 of partial rebreather mask
40-70% with oxygen flows at least 6 L/min
FiO2 of nonrebreather
60-80% with minimum flow of 10 L/min
Hydrochlorothiazide effect on K
hypokalemia
Potassium sparing diuretics
The K+ STAys with Spironolactone, Triamterene, Amiloride. Also eplerenone
Name 3 loop diuretics
furosemide, bumetanide, ethacrynic acid
Thiazides effect on labs
hypokalemia, hypercalcemia, hypomagnesemia, hyponatremia
lithium toxicity ass’d with
hypermagnesemia –> PR prolongation and widening QRS
monitor required for all anesthetics
Continuous ECG should be used for all anesthetics regardless of whether sedation is used or not.
When used alone, which of the following leads is the MOST SENSITIVE for detecting myocardial ischemia?
When used alone, V5 is the most sensitive for myocardial ischemia.
Intraoperative monitoring of Leads II and V4 is the preferred lead combination as it allows for rhythm monitoring and is sensitive for myocardial ischemia. Alone, V5 has the highest sensitivity for myocardial ischemia, however, this is not recommended for intraoperative monitoring.
Possible Contraindications To Ketamine:
Possible Contraindications To Ketamine:
- Increased ICP with spontaneous ventilation
- Intracranial mass lesion with spontaneous ventilation
- Open eye injury or other ophthalmologic disorder (increased IOP)
- Ischemic heart disease (as sole anesthetic agent)
- Vascular aneurysms (as sole anesthetic agent)
- Psychiatric disease such as schizophrenia
Meds that cause pain with injection:
Pain on injection is common with many medications including propofol, etomidate, diazepam, methohexital, and rocuronium. In general, it has not been shown to occur on injection with opioids, ketamine, midazolam, fospropofol, or dexmedetomidine.
How do other meds affect digoxin?
Amiodarone and nifedipine may increase the serum concentration of digoxin.
Sucralfate may decrease the serum concentration of digoxin.
Hypokalemia potentiates the effect and toxicity of digoxin, and potassium should be monitored in patients receiving potassium-losing diuretics such as furosemide.
Tolvaptan
Tolvaptan is a vasopressin receptor type 2 (V2) antagonist. Tolvaptan was originally approved for use in patients with acute heart failure but is now used in patients with excessive antidiuretic hormone secretion (SIADH). Tolvaptan may cause hypotension due to diuresis and is not the drug of choice in this patient with TBI.
First-line med in patients with TBI, increased UOP, hypotension
Vasopressin is the first-line vasopressor in patients with traumatic brain injury (TBI), increased urine output, and hypotension (neurogenic diabetes insipidus)
Coronary perfusion pressure
CPP = (Aortic DBP – LVEDP)
When is LV perfused? RV?
The left ventricle is perfused only during diastole. The right ventricle is perfused throughout the cardiac cycle but receives its greatest perfusion during peak/late systole and early diastole.
Chi square
The chi-square test is a nonparametric test to compare nominal or ordinal data comprising of one to multiple sample tests.
Power
Increasing the alpha (type I error/false-positive) will increase the power. The larger the alpha, the lower the chance of a false-negative conclusion (type II error/beta). Conversely, increasing the beta will decrease the power. Power = 1 - beta.
alpha
probability of type I error
beta
probability of type ii error
4 ways to increase power
There are four ways to increase power (decrease type II error):
1) Increase alpha: the smaller the alpha, the greater the chance of a false-negative conclusion (risky, as this increases type I error).
2) Decrease population variability (difficult to control).
3) Increase the sample size.
4) Make the difference between the conditions greater (most important factor in decreasing a type II error but difficult to control/manipulate).
Why nitrous absorbed faster than des
The absorption of nitrous oxide is augmented by the concentration effect, making the rate of absorption faster than desflurande despite their similar blood gas partition coefficients.
most likely cause of adverse outcome related to anesthesia equipment
Adverse outcomes secondary to equipment related malfunction or misuse occur, with misuse being the primary issue. Proper training and upkeep of the equipment can help decrease the risk. However, it is most likely secondary to human error which cannot be completely eliminated.
assist control ventilation
Pressure vs. time tracings of AC ventilation can be recognized by the lack of spontaneous breathing independent of the ventilator. All breaths involve full ventilator support and are synchronized with patient effort, when present.
monitor lovenox
monitor unfractionated heparin
Although not routinely necessary, the anticoagulant effects of enoxaparin can be monitored by measuring factor Xa activity. Unfractionated heparin is monitored using either aPTT or ACT, depending on the clinical situation.
best indicator of hepatic synthesis
Albumin can be used to monitor long-term liver synthetic function, however it must be noted that many other diseases can cause hypoalbuminemia. Monitoring prothrombin time gives the clinician a better understanding of acute hepatic protein synthesis capabilities.
single blinded study
only the participants are blinded
bumetanide
loop diuretic
volatile gas effect on neuromuscular blockade
All volatile agents augment neuromuscular blockade by directly causing skeletal muscle relaxation and acting synergistically with NMBDs. Desflurane causes the most block potentiation.
order of gases effect on NMB
Overall, it has been estimated that desflurane most significantly augments neuromuscular blockade (by as much as 60%), followed by isoflurane and sevoflurane (as much as 40%), then nitrous oxide (20%).
which NMBDs effects are affected by gases
These effects are more pronounced with the aminosteroid nondepolarizing NMBDs (e.g. rocuronium, vecuronium, pancuronium) than the benzylisoquinoline nondepolarizing NMBDs (e.g. cisatracurium, mivacurium, atracurium).
carotid body
The carotid body chemoreceptors are located at the bifurcation of the common carotid arteries bilaterally. The chemoreceptors are stimulated to increase minute ventilation in response to decreases in PaO2 below 60-65 mm Hg.
relapse rate of residents
At least 40% of anesthesiology residents who were found to have substance use disorder during training relapsed.
fent patch timing
The median time to peak plasma fentanyl concentration is approximately 30 hours following placement of a transdermal fentanyl patch. Onset is approximately 6-8 hours after placement.
time of max LA doses
The maximum allowable doses are for the following time windows:
Chloroprocaine: 30-60 minutes
Lidocaine: 60-90 minutes
Ropivacaine: 90-120 minutes
Bupivacaine: >120 minutes
The rate of systemic absorption of LAs from the injection site correlates…
The rate of systemic absorption of LAs from the injection site correlates directly with the vascularity of the injection site: intravenous > tracheal > intercostal > caudal/paracervical > epidural > brachial plexus > sciatic/femoral > spinal > subcutaneous.
LA max doses
Lidocaine (plain): 5 mg/kg Lidocaine (with epi): 7 mg/kg Bupivacaine (plain): 2.5 mg/kg Bupivacaine (with epi): 3 mg/kg Ropivacaine (plain only): 3 mg/kg Chloroprocaine (plain only): 12 mg/kg Chloroprocaine (with epi): 14 mg/kg Mepivacaine: (plain or with epi): 7
how does MAP relate to SVR and CO
MAP ~ CO * SVR
thyrotoxicosis what blood gas effects
Thyrotoxicosis will cause a mixed respiratory and metabolic acidosis
NPO time for breast milk
4 hours
NPO time for clear liquids
2 hours
NPO time for infant formula
6 hours
NPO time for non-human milk
6 hours
NPO time for light meals (toast and clears)
6 hours
NPO time for fried or fatty foods
8 hours, even for regional or MAC
Medication effect alterations in burn patients:
Severe burns lead to hypoalbuminemia which increases the free fraction of many anesthetic drugs including benzodiazepines and opioids. Lower doses of benzodiazepines should be considered, while higher doses of opioids are usually required due to the rapid development of tolerance. Insulin resistance is seen due to increased catecholamine and corticosteroid levels. Proliferation of extrajunctional acetylcholine receptors leads to exaggerated hyperkalemia with succinylcholine use and resistance to nondepolarizing neuromuscular blockers.
Sux burn guidelines
When the burned area exceeds 10% of the total body surface area (TBSA), succinylcholine administration between 24 hours and 1 year after the injury becomes contraindicated due to exaggerated hyperkalemia.
formula for maximum allowable blood loss
MABL = [EBV * (starting Hct - target Hct)] / (starting Hct)
estimated blood volume for premature infant
90-105 ml/kg
estimated blood volume for newborn
80-90 ml/kg
estimated blood volume for infant
70-80 ml/kg
estimated blood volume for child
70-75 ml/kg
estimated blood volume for adult female
60-65 ml/kg
estimated blood volume for adult male
65-70 ml/kg
Risk factors for intraop awareness
Risk factors for awareness under anesthesia include: substance abuse (opioids, benzodiazepines, cocaine), history of awareness, history of difficult intubation or anticipated difficult intubation, chronic pain patients using high doses of opioids, cesarean delivery, trauma and emergency surgery, use of neuromuscular blockade, total intravenous anesthesia, and limited hemodynamic reserve.
Dexmedetomidine bolus vs infusion hemodynamic effects
Dexmedetomidine has varying hemodynamic effects depending on whether it is given as a bolus or as an infusion. A bolus can produce transient hypertension while an infusion may cause a slight decrease in pressure that returns to baseline as the infusion continues. Cardiac output and heart rate decrease to varying degrees with bolus and infusion dosing.
complete heart block caused by blockage in which coronary artery
About 85% of the population is right-dominant with the RCA giving rise to the PDA. The AV node is supplied by a branch of the RCA in right-dominant patients and complete heart block is most commonly caused by a myocardial infarction involving the RCA.
SA node supplied by
The SA node is supplied by the RCA in about 60% of cases and by the LCA or its branches in about 40% of cases. Supply of the SA node does not depend on coronary dominance of the patient.
what causes bronchoconstriction
The parasympathetic nervous system contributes a great deal to bronchoconstriction. The etiology behind bronchoconstriction is only partially known and research is ongoing.
VIP effect on airway
Vasoactive intestinal peptide (VIP) immunoreactive nerves are widely distributed throughout the respiratory tract. VIP is a potent vasodilator and bronchodilator thus increased secretion would not cause bronchoconstriction. Vasoactive intestinal peptide protects against histamine-induced bronchoconstriction in asthmatics.
Relative contraindications to the use of closed circuit or low flow anesthetic techniques
Relative contraindications to the use of closed circuit or low flow anesthetic techniques include sevoflurane use and patients with alcoholism, malnutrition, cirrhosis, or ketoacidosis.
Alcoholics and patients with cirrhosis, malnutrition, or ketoacidosis have increased production of acetone which is removed by the lungs during exhalation. A closed circuit anesthetic technique would result in rebreathing of acetone which can lead to significant nausea, vomiting, and slow emergence. Similarly, heavy smokers have increased levels of carboxyhemoglobin which leads to exhalation of carbon monoxide.
Closed circuit anesthesia is a type of low-flow technique using a circle system in which the total fresh gas flow (oxygen and inhalational anesthetic) is equal to oxygen consumption and inhalational anesthetic metabolism (generally considered minimal). No gas is vented to the scavenger, therefore all remaining gas is rebreathed. In order to minimize fresh gas flow (FGF), only oxygen is used so as to avoid a hypoxic gas mixture. Exhaled carbon dioxide is converted to a comparable volume of water vapor by the absorbent and therefore does not enter into this approximation.
The required FGF (oxygen) can be determined by calculating the metabolic demand for oxygen, approximately 3-3.5 mL/kg/min (for adults) * patient weight in kilograms.
des and iso if run through CO2 absorber for long time
The dimethyl ethers desflurane (classically) and isoflurane can be degraded to carbon monoxide when exposed to a desiccated CO2 absorbent. This typically occurs when the absorbent has been exposed to high fresh gas flows for >24 hours. The absorbent becomes dry and hot. CO exposure is more likely with increasing agent concentration and when potassium hydroxide is used.
Risk of adding bicarb to what LA?
The addition of bicarbonate to ropivacaine or bupivacaine can cause precipitant to form in solution.
Why add bicarb to LA? What is the risk?
The addition of bicarbonate to ropivacaine or bupivacaine can cause precipitant to form in solution.
Local anesthetics are basic molecules that act on the cytoplasmic side of voltage-gated sodium channels in nerves. Therefore, the local anesthetic must pass through the cellular membrane to reach its target. To travel through the nerve membrane the local anesthetic needs to be in the unionized form. When the pH of a solution is less than the pKa the molecule will be ionized. When the pH of a solution is equal to the pKa, 50% of the molecules will be ionized and 50% will be unionized.
Ionized form is BH+
Metoclopramide
Metoclopramide is a dopamine antagonist that causes increased gastric motility and increased lower esophageal sphincter tone.
Positive lusitropy on myocardial pressure-volume loop:
Positive lusitropy results in a rightward and downward shift of the diastolic filling phase on the myocardial pressure-volume loop. This results in increased CPP, LVEDV, and SV.
Lusitropy is defined as
myocardial relaxation
Doppler error increases when angle is greater than
20 degrees
2 most important adverse effects of sugammadex
And other adverse effects
The two most important adverse effects of sugammadex include anaphylaxis/hypersensitivity reactions and potentially severe bradycardia. Other important adverse effects include, but are not limited to arrhythmias, tachycardia, hypotension, prolongation of PT/INR and aPTT, and increased risk of unintentional pregnancy due to inactivation of hormonal contraceptives.
TRALI PaO2:FiO2 ratio
PaO2:FiO2 ratio is typically 200-300 mm Hg. In this case, 100 mm Hg / 0.4 = 250 mm Hg.
Dopamine mechanism
stimulation of beta-1 receptors and release of norepinephrine -> increase in heart rate, systolic blood pressure, and pulse pressure
At lower concentrations, dopamine primarily acts on the D-1 dopamine receptors to produce vasodilation of the renal, mesenteric, and coronary vasculature.
dopamine adverse effects
Dopamine can cause tachyarrhythmias and myocardial ischemia. Furthermore, at higher doses a decrease in splanchnic blood flow may occur with resultant gut ischemia. Dopamine infusions may alter endocrine and immune functions including decreased secretion of thyroid stimulating hormone, prolactin, and growth hormone. Dopamine decreases the ventilatory response to hypoxemia and hypercarbia secondary to exertion of a depressive effect on the carotid bodies.
Furthermore, dopamine may impair regional ventilation/perfusion matching in the lung, potentially causing or worsening hypoxemia. If dopamine is extravasated, it can result in skin necrosis and sloughing thus administration into a central line is recommended.
dopamine dosing
Low dosing: 0.5 to 3 mcg/kg/min
Moderate dosing: 3 to 10 mcg/kg/min
High dosing: >10 mcg/kg/min
Most useful Mapleson circuit for spontaneous ventilation
Here is a mnemonic to help remember the most useful circuits for spontaneous or controlled ventilation:
All Dogs Can Bite (spontaneously): A > D > C > B
Dead Bodies Can’t Argue (controlled): D > B > C > A
Most useful Mapleson circuit for controlled ventilation
Here is a mnemonic to help remember the most useful circuits for spontaneous or controlled ventilation:
All Dogs Can Bite (spontaneously): A > D > C > B
Dead Bodies Can’t Argue (controlled): D > B > C > A
Renal failure acid/base stuff
Renal failure often causes metabolic acidosis due to the kidneys’ inability to regulate extracellular fluid H+ ion concentration. Normal kidney function reabsorbs filtered bicarbonate, secretes H+ ions, and produces new bicarbonate ions.
lower alpha
lower chance of type I error but higher chance of type II
Pseudocholinesterase deficiency affects which 2 drugs
Pseudocholinesterase deficiency prolongs the actions of succinylcholine and mivacurium which can lead to prolonged neuromuscular blockade and apnea.
most common pseudocholinesterase deficiency variants
a and k
who is likely to be allergic to latex?
Health care workers, atopic individuals, spina bifida, and those with allergies to certain foods (avocados, bananas, chestnuts, kiwi fruit, papayas, potatoes, tomatoes) have an increased incidence of latex allergy.
How does lithium interact with NMBDs and volatiles?
Lithium prolongs action of both depolarizing and nondepolarizing neuromuscular blockers.
TrueLearn Insight : Lithium may decrease anesthetic requirements (lower MAC) because it blocks brainstem release of norepinephrine, epinephrine, and dopamine.
Toradol does what to the kidneys
Ketorolac can decrease GFR, especially when administered for greater than 5 days, via inhibition of afferent renal artery vasodilation.
STEMI vs ST depression
Acute ST elevation represents transmural myocardial injury whereas ST depression represents subendocardial ischemia. Recognition is important as treatment strategies between the two are different.
Advantages/disadvantages of using closed circuit
Advantages of using a closed circuit or low-flow anesthetic technique include decreased use of fresh gas, decreased volatile anesthetic use, conservation of heat and humidity, improved mucociliary function, and decreased occurrence of microatelectasis. Rebreathing of noxious gases, such as acetone or carbon monoxide, increases the risk of postoperative nausea and vomiting.
What chemo drug cause periph neuropathy?
Vincristine is associated with peripheral neuropathy and patients on this medication are at increased risk for neuropathy during general anesthesia.
TrueLearn Insight : Accidental intrathecal injection of vincristine can cause ascending radiculomyeloencephalopathy, which is almost always fatal.
Common Chemo-Toxicities: Cisplatin, Carboplatin: Vincristine, vinblastine: Bleomycin, Busulfan: Doxorubicin: Trastuzumab: Cyclophosphamide: 5-FU, 6-MP, methotrexate:
Common Chemo-Toxicities:
Cisplatin, Carboplatin: acoustic nerve damage, nephrotoxicity
Vincristine, vinblastine: peripheral neuropathy
Bleomycin, Busulfan: pulmonary fibrosis
Doxorubicin: cardiotoxicity
Trastuzumab: cardiotoxicity
Cyclophosphamide: hemorrhagic cystitis, possible cardiotox
5-FU, 6-MP, methotrexate: myelosuppression
Des effect on heart
Desflurane increases heart rate and decreases both mean arterial pressure and systemic vascular resistance while maintaining cardiac output. Some studies have shown desflurane can better maintain blood pressure and systemic vascular resistance when compared to isoflurane. Invasive measurements of left ventricular indices demonstrate that desflurane does not alter regional or chamber stiffness and therefore, desflurane does not affect left ventricular diastolic function.
Milrinone in renal failure
Milrinone is excreted via the kidneys in its unconjugated form and therefore dosage should be adjusted in the setting of renal failure.
Hormones in stress response
In response to stress, GH, ACTH, prolactin, and AVP all have an increased secretion while TSH, LH, and FSH are unchanged (although some studies report an increased secretion of TSH). The increased pituitary secretion will cause an increase in the target organ secretion: cortisol and aldosterone in the adrenal cortex, glucagon in the pancreas. Cortisol promotes glycogenolysis, gluconeogenesis, protein catabolism, lipolysis, and ketone body production. Protein catabolism is stimulated during stress predominantly from the skeletal muscle but also through some visceral muscle protein breakdown. Fat metabolism occurs mainly through lipolysis (conversion of triglycerides to glycerol and fatty acids). In addition, glucagon also promotes hepatic glycogenolysis and gluconeogenesis.
Perioperative insulin
In the perioperative period, insulin levels vary depending on multiple factors. In the operative period, the pancreas releases less insulin and a certain degree of peripheral insulin resistance is observed. Insulin is a key hormone that is usually secreted in response to hyperglycemia, promoting glucose utilization in the cells. During the stress of surgery, the islet cells of the pancreas, where insulin is made, are inhibited secondary to catecholamines. The metabolic results of this endocrine response include mobilization of energy stores along with alterations in salt and water metabolism. Blood glucose concentrations increase during stress and the degree of glucose elevation is related to the intensity of the surgery. Postoperatively, insulin concentrations escalate because of the increases in plasma glucose that occurred during the operative period and the epinephrine-induced beta-adrenergic stimulation.
Plasma local anesthesia concentrations based on block location
Plasma local anesthetic concentrations following regional techniques, from highest to lowest, are: intercostal blocks > caudal > epidural > brachial plexus > intravenous regional > lower extremity blockade.
TrueLearn Insight : Mnemonic - ICEBALLS: intercostal > caudal > epidural > brachial plexus > axillary > lower limb > subcutaneous
Benzos effect on resp
Midazolam and all benzodiazepines cause a dose dependent decrease in minute ventilation. The decreased minute ventilation is mainly a result of decreased tidal volume. Benzodiazepines decrease the respiratory sensitivity to CO2 and act synergistically with opioids.
Benzos
Benzodiazepines are anxiolytic, sedating, and amnestic; all properties that may be advantageous prior to surgery. Commonly used benzodiazepines include midazolam, lorazepam, and diazepam. Benzodiazepines act on the GABAa receptor and lorazepam has the highest affinity for the GABAa receptor of those listed. Midazolam has the fastest onset of action and shortest duration of action for those listed. Benzodiazepines reduce cerebral blood flow and cerebral metabolic rate. Additionally, benzodiazepines increase the seizure threshold and are often used to terminate seizures. Benzodiazepines have only moderate effects on the cardiovascular system, in a dose dependent manner. Midazolam causes the greatest decrease in mean arterial pressure of the benzodiazepines listed, but those effects are less pronounced than propofol or thiopental. Heart rate and cardiac output are unaffected by benzodiazepines.
Rebreathing in mapleson ciricuits
When determining the amount of rebreathing in the Mapleson circuits:
Rebreathing during spontaneous ventilation: A > D > C > B
Rebreathing during controlled ventilation: D > B > C > A
A mnemonic to remember this is: All Dogs Can Breathe during spontaneous ventilation but Dead Babies Can’t Assist during controlled ventilation.
most common circuit in US
circle system
Mapleson F system
Jackson Rees
At an atmospheric pressure half that of sea level, the dialed desflurane inspired concentration setting…
At an atmospheric pressure half that of sea level, the dialed inspired concentration setting needs to be doubled on most desflurane vaporizers, including the Datex-Ohmeda Tec 6, to produce the same level of anesthesia
Note that most desflurane vaporizers operate differently from most variable-bypass vaporizers which are commonly used for isoflurane and sevoflurane administration. The latter compensate for changes in atmospheric pressure (within certain ranges) by up- or down-regulating the delivered percent concentration in order to maintain a constant partial pressure of the agent.
shark fin on capnograph
obstructive pulmonary pattern (bronchoconstriction from asthma or bronchospasm)
One-lung ventilation, how does it effect uptake of volatiles?
One-lung ventilation (OLV) creates a right to left pulmonary shunt, which has the greatest effect on the less soluble inhalational anesthetics, such as desflurane.
Pulmonary venous admixture from a non-ventilated lung will reduce the Pa of an inhalational anesthetic, thereby increasing the time it will take for the agent to reach equilibrium. This effect is augmented for less soluble volatile agents because their low blood:gas coefficients lead to a relatively greater dilutional effect from the non-ventilated lung.
Large quantities of natural licorice will induce
Large quantities of natural licorice will induce hyperaldosterone-like effects including: hypokalemia, hypertension, hypernatremia, fluid overload, and metabolic alkalosis.
Allergies to local anesthetics
True allergic reactions to local anesthetics are rare. Aminoester local anesthetics are more likely to elicit allergic reactions compared to aminoamides because they are derivatives of para-aminobenzoic acid, a known allergen. Also potential allergens are the preservatives included in some formulations, methylparaben (structurally related to PABA) and sulfites.
Thiopental effect on cerebral blood flow and metabolic rate
The cerebral flow-metabolism relationship and cerebral autoregulation remain intact with the use of thiopental. Thiopental decreases both CBF and CMRO2 by 30% with induction doses and by 50% upon achievement of an isoelectric EEG.
TrueLearn Insight : Burst suppression on EEG is the goal target of reducing CMRO2 during an open cerebral aneurysm clipping. Burst suppression sufficiently indicates depressed CMRO2 while providing predictability of recovery and awakening once the IV anesthetic is turned off.
Gases effect on CBF and CMRO2
Inhalational anesthetics at ≥1 MAC increase CBF and decrease CMRO2, causing an uncoupling of the flow-metabolism relationship.
How much fibrinogen is in cryo
Cryoprecipitate contains about 200 mg of product in each unit. Ten units of cryoprecipitate will typically raise a 70kg patient’s fibrinogen by 70 mg/dL.
So 10 units would add 2 gm of fibrinogen
indications for cryo
hypofibrinogenemia, von willebrand disease, hemophilia A
Nerve fiber nociception
Nerve fibers that conduct nociceptive information are A-delta fibers and C fibers. C fibers are small and unmyelinated. A-alpha fibers are large and myelinated. A-alpha fibers carry proprioceptive and motor fibers.
A is faster than B or C.
TrueLearn Insight : A mnemonic for differential blockade is “Sympathetic People Matter”: Sympathetics > Pain > Motor for neuraxial blockade levels.
Sympathetics blocked first (and 2-4 levels higher than motor
Pain blocked second and 2-3 levels higher than motor
Zero order vs First order kinetics
First order kinetics describes a situation where a constant proportion (percentage) of a medication is removed per unit time, whereas zero order kinetics describes a situation where a constant amount of medication is removed per unit time.
Drugs that typically follow zero-order kinetics:
Drugs that typically follow zero-order kinetics are THE PAW: theophylline, heparin, ethanol, phenytoin, aspirin, warfarin.
Zero or First order is dependent on liver blood flow?
Liver blood flow dependent elimination is characteristic of first-order kinetics, not zero-order kinetics.
Some drugs, such as propofol, are so highly extracted by their metabolizing organ, such as the liver, that their rate of metabolism is proportional only to liver blood flow. Progressively less drug is still eliminated per unit time as smaller amounts of drug are present in the blood to be metabolized, which is the definition of first order kinetics.
Fasting energy
Fasting Period
10-12 hours: Decrease insulin; stimulate glucagon; increase fatty acid oxidation for energy
2-3 days: Increase in ketone bodies for brain to use as alternate energy
3 weeks: Protein breakdown/amino acid utilization for energy
Epidural for patient on heparin
Patients receiving heparin for more than five days should have a platelet count checked prior to epidural placement or catheter removal (in case they have HIT). ASRA guidelines recommend waiting 4-6 hours before epidural placement in patients receiving 5000 U subcutaneous heparin BID or TID.
Where block glossopharyngeal nerve?
The glossopharyngeal nerve is blocked at the palatoglossal folds. The recurrent laryngeal nerve can be blocked with a transtracheal injection through the cricothyroid membrane. The superior laryngeal nerve can be blocked by either injection at the horn of the hyoid bone or by placing a pledget in the pyriform sinus. The mandibular portion of the trigeminal nerve is blocked topically.
Where block RLN?
The glossopharyngeal nerve is blocked at the palatoglossal folds. The recurrent laryngeal nerve can be blocked with a transtracheal injection through the cricothyroid membrane. The superior laryngeal nerve can be blocked by either injection at the horn of the hyoid bone or by placing a pledget in the pyriform sinus. The mandibular portion of the trigeminal nerve is blocked topically.
Where block superior laryngeal nerve
The glossopharyngeal nerve is blocked at the palatoglossal folds. The recurrent laryngeal nerve can be blocked with a transtracheal injection through the cricothyroid membrane. The superior laryngeal nerve can be blocked by either injection at the horn of the hyoid bone or by placing a pledget in the pyriform sinus. The mandibular portion of the trigeminal nerve is blocked topically.
Where block mandibular portion of trigeminal nerve?
The glossopharyngeal nerve is blocked at the palatoglossal folds. The recurrent laryngeal nerve can be blocked with a transtracheal injection through the cricothyroid membrane. The superior laryngeal nerve can be blocked by either injection at the horn of the hyoid bone or by placing a pledget in the pyriform sinus. The mandibular portion of the trigeminal nerve is blocked topically.
Cipro
Ciprofloxacin (B) is a second-generation fluoroquinolone with a broad spectrum of activity. Ciprofloxacin acts by inhibiting topoisomerase type II and IV, which prevents replication of bacteria. The package insert for ciprofloxacin recommends administering ciprofloxacin over 60 minutes. Side effects of ciprofloxacin include QT prolongation, tendonitis, and photosensitivity. Ciprofloxacin has been associated with local skin reactions when administered faster than over 60 minutes. Histamine release has also been documented with ciprofloxacin in dogs.
Metronidazole
Metronidazole (C) a nitroimidazole antibiotic that causes inhibition of bacterial replication by inhibiting DNA synthesis of bacterial cells. Metronidazole works when partially reduced which is the reason why metronidazole is effective in anaerobic bacteria. Metronidazole should be infused over the course of 30 to 60 minutes. Metronidazole often causes disulfiram like effects when ethyl alcohol is taken after metronidazole.
Vancomycin
Vancomycin (D) is a glycopeptide antibiotic that inhibits cell wall synthesis by inhibiting N-acetylmuramic acid (NAM) and N-acetylglucosamine (NAG) crosslinking. Vancomycin is a large molecule that can cause histamine release from mast cells. Histamine release is more common with fast administration of vancomycin, leading to “Red Man’s Syndrome”. Vancomycin is recommended to be administered no faster than over 60 minutes. Vancomycin is eliminated primarily through the renal system and dose should be adjusted for patients with decreased renal function.
Naloxone
Naloxone, an opioid antagonist, has an onset of action of 1-2 minutes and duration of 30-60 minutes. Recurrence of respiratory depression can occur after naloxone administration if used to reverse a long-acting opioid overdose. Naloxone can also reverse opioid-induced nausea, vomiting, pruritus, and urinary retention. Side effects include an increase in sympathetic stimulation which can cause pulmonary edema and/or myocardial ischemia, particularly if a large bolus dose is given.
TrueLearn Insight : Opioid agonist-antagonists (e.g. nalbuphine, pentazocine, butorphanol, and buprenorphine) have limited effects on smooth muscles of the bladder, biliary tree, and intestines, therefore causing less urinary retention, biliary colic, and constipation compared with pure opioid agonists.
Phase 1 and Phase 2 blocks
Both phase 1 and phase 2 blockades of succinylcholine administration display decreased contraction with single twitch stimulus. Phase 1 blockade is associated with fasciculations, minimal fade to TOF (TOF ratio >70%), and enhancement of neuromuscular blockade (NMB) by anticholinesterases. Phase 2 blockade is associated with repeated doses or an infusion of succinylcholine, resembles NDNMB, and can be partially reversed with anticholinesterases.
Dibucaine number
The degree of pseudocholinesterase deficiency is established by the dibucaine number, which is proportional to the amount of normal pseudocholinesterase.
20 - homozygous
40-70 heterozygous
Dantrolene
Dantrolene directly blocks calcium release from the sarcoplasmic reticulum of skeletal muscle.
Dantrolene is unique among muscle relaxants in that its site of action is NOT at the extracellular portion of the nicotinic receptor but INTRACELLULAR on the sarcoplasmic reticulum of the skeletal muscle cells. Dantrolene is not a depolarizing or nondepolarizing neuromuscular blocking drug.
TrueLearn Insight : Dantrolene is given initially as an IV bolus (2.5 mg/kg) followed by repeat boluses every 5-10 minutes as needed. Some institutions may choose to place patients on dantrolene infusions or administer dantrolene 1 mg/kg every 6 hours for 24-72 hours in order to prevent recrudescence.
Chemo drugs avoid regional anesthesia
Central and autonomic nervous system toxicity and peripheral neuropathies occur with vincristine and cisplatin. Therefore regional anesthesia should be avoided.
Chemo drug avoid high FiO2
Bleomycin is associated with pulmonary toxicity and patients undergoing anesthesia should not receive high FiO2
Chemo drug interacts with succ
Cyclophosphamide interacts with succinylcholine, increasing apnea risk
Chemo drug avoid NSAIDs
NSAIDs should be avoided if methotrexate is used
IO access
Major complications from IO access occur in less than 1% of insertions. During code situations, the AHA recommends IO access over central access due to a faster insertion time, higher first-attempt success rate, and lower infection incidence.
Agent saturated vapor pressure (or partial pressure) formula
Agent SVP/Total pressure = Agent vapor volume/(Carrier gas volume+Agent vapor volume)
or
Agent SVP= (Agent vapor volume x total pressure)/(carrier gas volume + agent vapor volume)
Saturated vapor pressure of Sevo Enflurane Iso Halothane Des
Sevo 160 Enf 175 Iso 238 Halo 241 Des 669
Aortic Stenosis
ortic stenosis:
- Severe aortic stenosis is defined as a valve area less than 0.8 cm2 and a transvalvular pressure gradient higher than 50 mmHg.
- The “triad” of symptoms include: angina, syncope, and shortness of breath (dyspnea). The degree of symptoms does not correlate with the degree of stenosis.
- HR: normal sinus rhythm should be maintained since loss of the left atrial contraction will result in a dramatic decrease in stroke volume and blood pressure. A normal to slower heart rate is beneficial to allow as much time for ventricular filling as possible. Furthermore, elevations in heart rate can lead to ischemia due to decreased diastolic time.
- Contractility: want to maintain, avoid depression of contractility which can lower stroke volume.
- Preload: want to have adequate volume.
- Afterload: must be maintained distal to the stenotic lesion to ensure coronary perfusion. A decrease in blood pressure can lead to myocardial ischemia which will further worsen contractility.
- Cardiac resuscitation is not typically effective in patients with AS; code situations must be avoided as it is generally not possible to created adequate stroke volume with chest compression in these patients.
Aortic regurgitation
Aortic regurgitation:
- The magnitude of regurgitant volume depends on the diastolic time and the pressure gradient across the aortic valve (dependent on systemic vascular resistance).
- HR: must be kept above 80 bpm to prevent increases in the time for regurgitation. Decreased heart rates, which will increase diastolic time, will allow more regurgitation.
- Contractility: want to maintain.
- Preload: need adequate volume loading to ensure enough volume can move forward. Want to avoid overloading patient because this will increase regurgitant volume.
- Afterload: want to lower systemic vascular resistance which will attempt to prevent more regurgitation.
active form of local anesthetics
“active” form of local anesthetics is the ionized form [charged cation (BH+)]
what form of local passes through cell (to site of action)
the speed of onset of effect is determined by the proportion of local anesthetic in the unionized [basic, uncharged (B)] form.
Anything that increases the concentration or proportion of local anesthetic in its unionized form will speed the onset of analgesia.
The onset of effect of a local anesthetic is affected by
The onset of effect of a local anesthetic is affected by its concentration (higher is faster), lipid solubility (higher is faster), pKa (lower is faster), and environment pH (higher is faster). Anything that increases the concentration or proportion of local anesthetic in its unionized form will speed the onset of analgesia.
type of surgery PONV risk factor in children
strabismus surgery (crossed eye)
aprepitant
NK-1 receptor antagonist anti-emetic.
Metoclopramide
dopamine-2 receptor antagonist. WEAK anti-emetic. not recommended for PONV. not recommended as antiemetic for patients who have received prophylactic ondansetron intraoperatively.
alfentanil pKa
Alfentanil has the lowest pKa (6.5) and highest fraction of nonionized drug at physiologic pH
significantly lower than other opioids, resulting in a very high fraction of the drug existing in the nonionized form. Coupled with its moderate lipid solubility, this allows alfentanil to very rapidly cross the blood-brain barrier and have an ultra-short onset of action. The plasma-brain equilibration half-time of alfentanil is 0.9-1.1 minutes compared to 6.2 minutes for sufentanil, 4.7-6.4 minutes for fentanyl, and 139 minutes for morphine.
Ionized drugs are polar and do not readily pass through cell membranes whereas nonionized drugs are significantly more lipid soluble (often 103-104 times more soluble).
opioid pka rule of thumb
An opioid with a pKa less than physiologic pH (~7.4) will have a much greater nonionized fraction whereas an opioid with a pKa >7.4 will have a greater ionized fraction
spinal stenosis and spinal anesthesia
Patients with space-occupying extradural lesions or those that reduce the cross-sectional area of the spinal cord are most at risk for new or worsening neurologic injury from a neuraxial anesthetic. Although neurologic injury from neuraxial anesthesia is very rare, they tend to result in permanent deficits.
insulin-independent glucose uptake
Hepatocytes, most immune cells, erythrocytes, and brain neurons utilize insulin-independent glucose transporters for the majority of their glucose uptake.
therapeutic range of magnesium
The therapeutic range (for treatment of preeclampsia) for magnesium sulfate therapy is 5-9 mg/dL.
s/s of hypermagnesemia and ranges
Hypermagnesemia can lead to depressed cardiac conduction, widened QRS, and prolonged PR intervals on ECG at levels of >5-10 mg/dL. These effects are caused by magnesium’s ability to directly depress the contractile force of the myocardium.
Deep tendon reflexes are reduced at magnesium levels >5 mg/dL and are lost at >12 mg/dL.
Hypotension, bradycardia, and vasodilation can occur at levels >7 mg/dL. Magnesium produces vasodilation and hypotension by direct action on the vasculature, inhibition of vasoconstrictors, and reduction of peripheral vascular tone via blockade of sympathetic catecholamine release.
Muscle weakness, and hypoventilation (reflecting diaphragm weakness) occur at magnesium levels of 7-12 mg/dL.
Respiratory arrest occurs at 15-20 mg/dL and asystole can occur when >25 mg/dL.
Mg and NMBDs
Magnesium interferes with the release of neurotransmitters at synaptic junctions, thereby inhibiting neuromuscular function. Magnesium is therefore synergistic with neuromuscular blocking agents.
TEG prolonged R treatment
FFP
TEG MA decreased treatment
platelets
TEG prolonged K treatment
cryo
Prolonged K values suggest deficiencies of thrombin formation or generation of fibrin from fibrinogen/inadequate fibrinogen. Treatment consists of cryoprecipitate.
TEG teardrop configuration treatment
antifibrinolytics
supplements that interfere with plts fxn
garlic, ginger, gingko, vitamin E
ischemic optic neuropathy by surgery
An easy way to remember ION would be the location of the surgery predicts the type – posterior spine surgeries = posterior ION and anterior cardiac procedures = anterior ION.
power
The power of hypothesis testing refers to the probability of correctly rejecting Ho when Ha is true (i.e., the chance of having a true positive). Power = 1-β, where β is the error threshold (typically 0.1-0.2).
hormones that are inactivated by the lungs:
norepinephrine, bradykinin, atrial natriuretic peptide (ANP), endothelins, PGD2, PGE2, PGF2-alpha, leukotrienes, adenosine, ATP, ADP, and AMP, Serotonin
hormones that are activated in the lungs:
These include angiotensin I and arachidonic acid.
rates of transfusion transmissions
The risk of CMV transmission when non–CMV-screened leukoreduced cellular products are administered to CMV negative recipients is less than 1%. The risk of HIV, HCV, and human T-cell lymphotropic virus among all allogeneic donations is currently below 1 per 1,000,000 donations, and that of hepatitis B surface antigen is close to 1 per 300,000 donations.
effects of morphine on hemodynamics
Morphine reduces preload and afterload. This reduces myocardial oxygen demand and improves coronary perfusion pressures by reducing ventricular EDV and EDP. Morphine has minimal effect on myocardial contractility by itself but may cause myocardial depression when combined with volatile anesthetics. All µ-opioid agonists cause dose-dependent respiratory depression by decreasing the sensitivity of central chemoreceptors to elevated levels of CO2.
Preload reduction and vasodilatation are due to morphine’s histamine release
sux GI effects
Succinylcholine increases both LES tone and intragastric pressure. The former effect is greater than the latter, so the risk of aspiration is not increased. The increase in intragastric pressure can be offset by a priming dose of a nondepolarizing neuromuscular blocker.
CO2 absorbent most likely to form CO with des
Baralyme is the most likely to cause carbon monoxide formation with desflurane. Second is sodalime
other name for compound A
haloalkene
hydroxyethyl starches and side effects
Hydroxyethyl starches are synthetic colloids useful for volume resuscitation due to prolonged intravascular half-lives. Hetastarches are traditionally associated with a higher risk of coagulopathies (platelet adhesion interference, reduced factor VIII:C and vWF levels, and PTT prolongation) than the newer, lower molecular weight tetrastarches.
tetrastarches compared to hetastarches
tetrastarches are associated with less coagulopathies and cause less inhibition of platelet function
Although possible at lower doses, most of the coagulation side effects and potential for allergic reactions associated with 6% hetastarches occurred with administration >20-25 mL/kg. Accordingly, the maximum recommended daily dose is 20 mL/kg. The maximum recommended daily dose of tetrastarches is higher (50 mL/kg) due to their generally safer profile.
order volatiles re: total hepatic blood flow preservation
Preservation of THBF amongst volatile anesthetics at 1 MAC, from greatest to least, is sevoflurane > isoflurane > halothane
how does hyperventilation affect hyperkalemia
Hyperventilation lowers extracellular potassium levels by decreasing plasma CO2 levels. This leads to a left shift in the bicarbonate buffer system (see below) which lowers extracellular hydrogen ion concentration. This causes potassium to shift into the cells in order to maintain electrical neutrality.
CO2 + H2O < => H2CO3 < => H+ + HCO3-
coagulation factors in liver disease
Liver disease reduces factors II, VII, IX, X, as well as V, XI, and thrombin. Protein C is also reduced. Factor VIII and vWF are increased in patients with liver disease as they are produced extra-hepatically.
Elevated INR in liver disease
Elevated INR in liver disease patient does not indicate bleeding risk.
Coagulation management in liver disease patients
Coagulation management in liver disease patients:
1) Maintain platelet count at 50-60; in high-risk surgery maintain >100
2) Keep fibrinogen >100
3) Transfuse to maintain Hgb > 7
4) Do not give FFP prophylactically or chase INR levels
- Increased INR in these patients does not necessarily reflect risk of bleeding
- If FFP is to be given, dose is 20-40 mL/kg
Nicardipine metabolism
Nicardipine is metabolized by the liver and eliminated via gastrointestinal tract. Renal insufficiency has no effect on nicardipine use. Severe hepatic insufficiency results in significantly prolonged nicardipine half-life.
Nicardipine
Nicardipine is a calcium-channel blocker; more specifically, it is an antagonist of calcium influx through the slow channels of cell membranes. It is an effective coronary and peripheral arterial dilator. Nicardipine can be used to relieve angina, especially those due to coronary artery spasms. It is also useful as an anti-hypertensive drug, particularly in neurosurgical patients. However, the advantage of nicardipine is that it does not decrease cardiac function.
Nicardipine (intravenous and oral) can cause an increase in heart rate in about 25% of the people. This tachycardia is NOT due to baroreceptor response, rather due to sympathetic activation. Nicardipine decreases systemic vascular resistance, but also increases cardiac contractility (C). The exact mechanism of this positive inotropic effect is unknown.
There seems to be no increased risk of bronchospasm in patients with lung diseases receiving nicardipine (A). In fact, some studies suggest that nicardipine may increase forced expiratory volume over one second (FEV1) and forced vital capacity (FVC).
fresh gas flow in mapleson D circuit for
controlled ventilation
spontaneous ventilation
Fresh gas flow (FGF) must be greater than or equal to 1-2 times minute ventilation in the Mapleson D semi-open breathing system to prevent rebreathing during controlled ventilation.
The FGF during spontaneous ventilation must be equal to 2-3 times minute ventilation in the Mapleson D, E, and F circuits. These semi-open circuits are not the most efficient systems for spontaneous ventilation. They are, however, the most efficient semi-open breathing circuits for controlled ventilation.
drugs that inhibit P450
Drugs known to inhibit P450 enzymes include fluconazole, metronidazole, valproic acid, and ciprofloxacin.
Inhibit Val from Cipping the Flu on the Metro
drugs that induce P450
barbiturates, phenytoin, rifampin, carbamazepine, and ethanol, and st. john’s wort
Induce Barbie with Alcohol and she’ll eat Carbs listen to Riffs and get Warts on her Toe
Transtracheal injection of local anesthetic will block the
Transtracheal injection of local anesthetic will block the recurrent laryngeal nerve.
which abx interact with NMBDs and to what effect?
Antibiotics including aminoglycosides, polymyxins, tetracyclines, lincomycin, and clindamycin can cause prolonged neuromuscular blockade when given in conjunction with a paralytic agent.
Test for acute hemolytic transfusion reaction
Acute hemolytic transfusion reaction carries significant morbidity and mortality. Laboratory testing includes evidence of hemolysis with a positive direct antiglobulin test. Cessation of the transfused unit is most important, as severity of reaction is proportional to amount of blood transfused.
antiglobulin eponym
Coombs test
direct coombs test
A direct test detects antibodies present on the red blood cell surface.
Coombs test detects antibodies against the red blood cell; there are two types – direct and indirect. Both of these tests detect the presence of antibodies and/or complement.
The direct Coombs test can be positive in many situations such as autoimmune hemolytic anemias, hemolytic disease of the newborn, and drug-induced hemolysis. A direct test detects antibodies present on the red blood cell surface.
indirect coombs
An indirect Coombs test detects free antibodies in the blood against red blood cells
Coombs test detects antibodies against the red blood cell; there are two types – direct and indirect. Both of these tests detect the presence of antibodies and/or complement.
An indirect Coombs test detects free antibodies in the blood against red blood cells and is used in testing of samples prior to blood transfusion and in prenatal testing of pregnant women.
AMS, hypothermia, non-pitting edema
Myxedema coma is an extreme form of hypothyroidism that is classically characterized by altered mental status, hypothermia, and non-pitting edema. It is most commonly seen in patients with chronic hypothyroidism in the setting of a physiologic stressor such as infection and is considered a life threatening emergency.
Pseudocholinesterase deficiency affects which drugs
Pseudocholinesterase deficiency is typically an inherited enzyme abnormality that results in abnormally slow metabolic degradation of exogenous choline ester drugs such as succinylcholine, mivacurium, ester local anesthetics, cocaine, and heroin.
Remifentanyl metabolism
nonspecific tissue and blood esterases (red cell esterase)
echothiophate
Patients who have been receiving echothiophate eye drops are at risk for significant prolongation of succinylcholine’s effects for up to 2 weeks after therapy is discontinued.
When hold aspirin?
Patients taking daily aspirin should generally continue the medication perioperatively. Aspirin should be held prior to intracranial neurosurgical procedures, middle ear surgery, posterior eye surgery, intramedullary spine surgeries, and possibly prostate surgeries.
circle system
inspiratory valve, y-piece, expiratory valve, popoff, CO2 absorber, fresh gas flow, inspiratory valve…
closing capacity
Closing capacity (CC) is the volume remaining in the lungs during expiration when alveoli BEGIN to close
Closing capacity is equal to the sum of the residual volume (RV) and the closing volume
bronchoconstriction can be stimulated by
Bronchoconstriction occurs due to the contraction of the smooth muscles located in the airways. This can be mediated by the parasympathetic nervous system, the non-adrenergic non-cholinergic (NANC) neurons, or the alpha-adrenergic receptors.
Helium
Helium is useful with increased airway resistance and turbulent flow, as is seen with decreasing airway radius, because helium has a low gas density. The low gas density decreases resistance with turbulent flow and increases the chance for development of laminar flow
Resistance to laminar flow equation
Resistance to laminar flow is constant and quantified by the equation:
R = 8*(length)(viscosity)/(π * r^4)
what medication reduce mortality after MI
ACE inhibitors reduce mortality after myocardial infarction.
exenatide
Non-insulin injectable such as exenatide (a hormone found in the saliva of the Gila monster) decreases glucagon secretion.
acarbose
Alpha-glucosidase inhibitors such as acarbose reduce glucose absorption from the intestines
Sulfonylureas and meglitinides
Sulfonylureas and meglitinides are groups of anti-diabetic medications that stimulate insulin secretion.
Metformin in periop period
Metformin may be continued through the perioperative period. Evidence shows that the occurrence of lactic acidosis is rare
The exception is patients with renal dysfunction, who will need to discontinue the metformin 24-48 hours prior to surgery
Insulin periop
With regards to insulin therapy, there are different types of insulin, each with varying onset time and duration: rapid-acting (lispro, aspart), short-acting (regular), intermediate (NPH), and long-acting (glargine, detemir).
Pre-operatively, patients on rapid or short-acting insulin can continue it until the day of surgery without any other changes.
Those taking intermediate insulin (usually twice a day dose) should take only 75% of the normal dose the night before surgery, and 50% of the normal dose the day of the surgery.
With long-acting insulin, the patient needs to reduce their dose by 50% on the morning of the surgery.
buprenorphine
mu partial agonist, kappa antagonist
low doses 25-40 times more potent than morphine
ceiling effects, esp for resp depression
cessation -> only mild withdrawal sx
cisatracurium clearance influenced by
Cisatracurium undergoes nonenzymatic Hofmann elimination in plasma. The reaction speed is increased with higher pH and higher temperature. As the drug undergoes minimal renal or hepatic metabolism, it is safe to use in patients with significant kidney or liver disease.
Mechanism of BP effects of volatiles
Sevoflurane, desflurane, and isoflurane decrease arterial blood pressure, SVR, and myocardial function comparably and in a dose-dependent manner. Halothane decreases blood pressure primarily by decreasing cardiac output and causes minimal changes to SVR.
What meds/conditions prolong non-depolarizing blockade:
Prolong Non-Depolarizing Blockade:
- Antibiotics (e.g. streptomycin, clindamycin, tetracyclines, aminoglycosides)
- Antiarrhythmics (e.g. calcium channel blockers)
- Dantrolene
- Ketamine
- Local anesthetics (high doses only)
- Lithium
- Magnesium
- Volatile anesthetic agents (des>sevo>iso)
- hypocalcemia
- hypothermia
- hypokalemia.
What meds shorten non-depolarizing blockade?
Shorten Non-Depolarizing Blockade:
- Anticonvulsants (e.g. phenytoin, carbamazepine (only vec))
- Cholinesterase inhibitors (e.g. neostigmine)
factors that increase closing capacity
A mnemonic for factors increasing closing capacity is ACLS-S: Age, COPD, LV failure (CHF), Smoking, Surgery.
factors that decrease FRC
A mnemonic for factors that decrease FRC is PANGOS: Pregnancy, Ascites, Neonate, General Anesthesia, Obesity, Supine position.
supine effect on closing capacity
none
Joint comission and ASA basic anesthesia standards:
According to TJC and ASA basic anesthesia standards, a qualified anesthesia provider must remain at all times with an anesthetized patient and continual evaluation of oxygenation, ventilation, circulation, and temperature is required.
Every patient receiving anesthesia shall have temperature monitored when clinically significant changes in body temperature are intended, anticipated or suspected
blood supply of spinal cord
The anterior two-thirds of the spinal cord is supplied by the anterior spinal artery and contributing radicular vessels, including the artery of Adamkiewicz (which most commonly arises between T9 and T12). The posterior one-third of the spinal cord is supplied by the two PSAs, along with collateral radicular vessels.
what colors are the tanks
nitrogen black helium brown CO2 gray O2 green air yellow N2O blue
vapor pressure of the volatiles
iso - 240 des - 681 sevo - 160 halothane - 243 N2O - N/A
neostigmine ceiling effect dose
The maximum dose of neostigmine is 70-80 mcg/kg at which point a “ceiling effect” takes place. This dose results in complete blockade of the acetylcholinesterase enzymes and occurs in approximately 10 minutes. If recovery does not occur by this time, repeated doses of neostigmine provide no additional benefit because the target is already blocked. At this point recovery takes place by elimination of the neuromuscular blocking agent from the neuromuscular junction.
In some instances additional anticholinesterase medication may cause paradoxical weakening. The anticholinesterase effect increases the amount of acetylcholine release. In an overdose, depolarization of the endplate caused by the excess acetylcholine can lead to a depolarization block, similar to that seen with succinylcholine.
ultrasound beam hit air and
reflects. weird i know
insulin effect on skeletal and cardiac myocytes
increases: glucose uptake amino acid uptake glycogen storage protein synthesis
insulin effect on adipocytes
increases:
fatty acid storage
glucose uptake
insulin effect on hepatocytes
increases:
macronutrient uptake
glycogen synthesis
fatty acid synthesis
confirm ETT placement in code
Although breath sounds can help confirm placement, they are not the most reliable method to confirm and monitor placement of the ETT as chest compressions may impede the ability to adequately hear.
The ACLS guidelines recommend continuous waveform capnography if available and it can be used to guide the adequacy of chest compressions as well. If continuous capnography is not available, colorimetric and non-waveform carbon dioxide detection cay be used. If those are unavailable, esophageal detector devices may be used.
Primary confirmation of endotracheal tube placement is based on clinical assessment. Secondary confirmation of endotracheal tube placement is achieved with ETCO2 detection (qualitative, quantitative, or continuous) or an esophageal detector device.
TrueLearn Insight : Chest compressions and defibrillation are the most important aspects of ACLS. Advanced airway devices can typically be deferred. Hyperventilation after endotracheal tube placement has been shown to worsen outcomes. Aim for one breath every 5-6 seconds (10-12 per minute). Each breath should be delivered over 1 second and achieve visible chest rise.
drugs whose effects are terminated by redistribution
The termination of action of the effects of a bolus dose of thiopental is primarily due to redistribution of the drug from the brain to peripheral tissues rather than by metabolism. The same is seen with bolus doses of methohexital, propofol, and fentanyl.
primary determinant of myocardial O2 consumption?
Heart rate is the primary determinant of myocardial oxygen consumption. The heart maximally extracts arterial oxygen and therefore relies on increased oxygen delivery via metabolically mediated vasodilation, coronary autoregulation, and reactive hyperemia.
amiodarone side effects
Adverse effects of acute amiodarone therapy include nausea, vomiting, phlebitis, hypotension, bradycardia, asystole, heart failure, shock, and acute respiratory distress syndrome. Chronic therapy affects PFTs, LFTs, and TFTs (pulmonary, liver, thyroid) and can also cause a blue/grey skin discoloration.
amiodarone
Amiodarone is a class III antiarrhythmic agent, although it has properties of both class I and II antiarrhythmics. It is used for atrial and ventricular arrhythmias and can be given intravenously or orally. It inhibits inactivated (phase 0) sodium channels, inhibits sympathetic activity by noncompetitive beta-receptor blockade, and blocks L-type (slow) calcium channels.
Local anesthetics mechanism
All LAs work by inhibiting sodium ion influx through neuronal membranes resulting in disruption of neural conductivity
FeNa formula
[(UNa)/(UCr)]/[(PNa)/(PCr)] x 100
= [(PCr x UNa ) / (PNa x UCr)] x 100
FENa cutoffs
prerenal <1
intrinsic >2
postrenal >2
random urine sodium cutoffs
prerenal <20
intrinsic >20
postrenal >20
renin-angiotensin-aldosterone system
Renin is produced in the kidneys in response to decreased renal perfusion and cleaves angiotensinogen into angiotensin I. Angiotensin I is converted to angiotensin II by ACE in the lungs and kidneys. Angiotensin II then promotes aldosterone production. Angiotensin II and aldosterone both act to increase intravascular volume, raise systemic blood pressure, and maintain adequate GFR.
Monitor what labs for chronic dantrolene use
Chronic use of dantrolene is associated with hepatotoxicity and, in severe cases, may lead to liver failure and death if unrecognized. Patients on chronic dantrolene therapy should routinely have LFTs monitored.
uses for dantrolene
MH, serotonin syndrome, ecstasy overdose
chronically for: muscle spasticity
hypocarbia from hyperventilation can lead to what electrolyte abnormalities
Respiratory alkalosis, such as from hyperventilation, can cause electrolyte abnormalities such as hypocalcemia, hypokalemia, and hypophosphatemia. Hypocalcemia is caused by increased calcium binding to negatively charged plasma proteins as the proteins release hydrogen ions to restore physiologic pH.
Respiratory alkalosis is likely to produce HYPOkalemia. Hydrogen-potassium transporters pump hydrogen ions out of cells in the setting of alkalosis in order to restore physiologic pH. Simultaneously, potassium is pumped intracellularly to ensure electroneutrality, thus leading to hypokalemia.
Name some intrinsic renal etiologiess
Intrinsic renal etiologies and causes include tubular (acute tubular necrosis (B)), interstitial (acute interstitial nephritis (C)), and glomerular (vasculitic, microvascular, and immune complex disorders). Treatment includes removing and/or correcting the offending agent(s) while ensuring adequate renal perfusion.
pain management if patient can’t tolerate oral meds
Intravenous patient controlled analgesia is an excellent form of pain management when a patient is unable to tolerate oral medications. It usually results in a more continuous plasma concentration of medication and also helps the patient became more able to be in control of their pain.
basal rate?
and how hold to have PCA?
The panel recommended that IV PCA could be used in patients who were greater than six years of age and who were able to cognitively understand the concept of PCA. Furthermore, the panel recommended against basal infusion of opioids in opioid-naïve patients because the evidence does not show improved analgesia compared to PCA with no basal rate. Basal rates are associated with an increased risk of respiratory depression, nausea, and vomiting. The evidence of using a basal rate in patients who are opioid tolerant is lacking, however there may be a stronger rationale in that population because of the higher potential for under dosing and uncontrolled pain.
Initial treatment for hypercalcemia
Normal saline
Initial treatment for hypercalcemia should be aimed at volume correction. With restoration of the patient’s fluid deficit furosemide can be used to decrease calcium levels.
Which drugs can reduce the incidence of emergence delirium associated with the use of ketamine?
Ketamine is associated with a high incidence of psychomimetic reactions early in the recovery period. The incidence of these reactions can be decreased by coadministration of benzodiazepines, propofol, or barbiturates.
one of the most effective strategies for prevention of emergence delirium is the use of midazolam approximately five minutes prior to an induction with ketamine.
effects of st john’s wort
induction of cyp 3A4 - enhanced metabolism of lidocaine, alfentanil, midz
induction of cyp 2C9 - breakdown of warfarin - risk DVT
can alter drug responses with anti-rejection medications (i.e. cyclosporine)
stop at least 5 days prior to surgery
Mapleson A circuit minimum FGF
must be at least equal to minute ventilation in order to prevent rebreathing of exhaled gas during spontaneous ventilation
intrinsic INR of FFP
1.6-1.8
time to peak effect of vitamin K
24 hours
agent of choice for warfarin reversal prior to urgent/emergency surgery
PCC
brachial a-line
Brachial artery catheterization is low risk and can be used for long-term monitoring. Potential complications include thrombosis (most common of the vascular complications), infection, and median nerve injury.
potential risk of axillary a. a-line
The axillary artery runs through the axillary sheath, which contains the median, ulnar, and radial nerves. Bleeding during the puncture of the axillary artery can cause a hematoma to form within the sheath. This can result in nerve compression leading to serious neurological deficits.
aspirin mechanism of action
Aspirin irreversibly inhibits platelet function by blocking the formation of thromboxane A2
When a dose is administered, even though the medication will be metabolized the effects will continue for the life of that platelet. Thus, in order for the effects to be reversed, new platelets must be synthesized. For each day after interruption of any agent which irreversibly inhibits platelet function (aspirin, clopidogrel), approximately 10% to 14% of normal platelet function is restored. Therefore it can take 7 to 10 days for an entire platelet pool to be replenished.
what opioid can cause tachycardia
Opioids are routinely used to prevent tachycardia and reduce myocardial oxygen demand. However, high doses of meperidine can cause tachycardia due to its atropine-like effects.
(May also occasionally be seen with morphine as histamine release can cause transient hypotension with reflexive tachycardia)
causes of increased amplitute on SSEP
etomidate, ketamine, improved nerve conduction following spine surgery, return to normothermia after cooling
why geriatric patients require a reduced induction dose of thiopental?
Geriatric patients require a smaller induction dose of thiopental due to a decreased pharmacologic central volume of distribution (A) owing to a 10-15% loss in total body water.
Geriatric patients require a reduced induction dose of thiopental because these patients exhibit a decreased volume of distribution and there is a slower redistribution of thiopental to peripheral tissues.
methadone EKG effect
Methadone can produce or worsen a preexisting prolonged QT interval, which can lead to the lethal arrhythmia, torsades de pointes. This risk is increased with concurrent use of CYP3A4 inhibitors.
meperidine metabolite
Normeperidine, meperidine’s toxic metabolite, is neuroexcitatory and high concentrations can cause seizures.
cardiac output effect which volatiles
effects more blood soluble ones to greater extent (prolongs induction time)
leak; compare ascending to descending bellows
Ascending bellows have the advantage of providing a visual sign of system leak versus a descending bellows which can continue to fill with room air and would fail to detect a system leak.
Ascending bellows refers to the direction the bellows travel during exhalation. With a leak in the system the ascending bellows would fail to reach the top of the ventilator chamber.
Pressure goals for TBI
Maintenance of cerebral perfusion pressure is exquisitely important when caring for a patient with a traumatic brain injury. Even a single episode of hypotension decreases cerebral perfusion enough to affect outcomes. The CPP value to target lies within the range of 50-70 mm Hg according to current BTF guidelines.
Keep ICP below 20
most important for spinal block spread
Drug dosage, drug baricity, and patient positioning are the most important factors influencing level of spinal blockade. Drug volume is an important factor during epidural blockade.
blood pressure height correction
0.75 mmHg per 1 cm change in height
Decreased atmospheric pressure will result in __________ vaporizer output
Decreased atmospheric pressure will result in increased vaporizer output. Of note, the partial pressure will remain the same according to the Dalton Law.
Filling an isoflurane vaporizer with sevoflurane will _______ vaporizer output
Filling an isoflurane vaporizer with sevoflurane will decrease vaporizer output
des vaporizer at altiude
Alternatively, the desflurane vaporizer is electrically heated to 39 degrees centigrade, which creates a vapor pressure of 2 atmospheres inside the vaporizer, regardless of ambient pressure. The number on the dial reflects the percentage that will be delivered. So at any altitude, when you dial 5%, it will give you 5%. But when that 5% desflurane leaves the vaporizer at high altitude, what is delivered to the patient is 5% of a decreased ambient pressure, so the partial pressure of desflurane in the alveoli will be much less that it would be at sea level. Thus, you will need to dial a higher concentration at high elevation to attain the same clinical effect as at sea level with desflurane (Tec-9) vaporizer.
____ cardiac index with ________ pulmonary artery wedge pressure is suggestive of cardiogenic shock.
Low cardiac index with elevated pulmonary artery wedge pressure is suggestive of cardiogenic shock.
Cardiogenic shock (either systolic or diastolic associated) will lead to an increase in CVP and PAWP. There will be a decrease in cardiac index, blood pressure, and mixed venous oxygen saturation. Systemic vascular resistance and heart rate may be unchanged or increased.
grade 2a
partial view of glottis
grade 2b
only posterior extremity of glottis seen or only arytenoid cartilages
grade 3
only epiglottis seen, none of glottis seen
grade IV
neither glottis nor epiglottis seen
international color code for oxygen containers
white
how NIBP know MAP?
The point of maximal amplitude of oscillations corresponds to the mean arterial pressure (MAP). The values of systolic and diastolic pressures are determined using formulas that detect the rate of change in the oscillations.
retained tip of epidural catheter
The diagnostic test of choice for a retained epidural catheter fragment is computed tomography. Minor fragments may be left in place if they do not cause symptoms. Neurosurgical consultation should be considered for any symptomatic retained fragment or any fragment within the spinal canal.
Correct way to diagnose proper placement of central line
Pressure monitoring is required prior to vascular dilation when placing a central venous catheter. There are a variety of approaches and the ASA practice advisory has stepwise guidelines.
Recall that a pressure of 10 mmHg correlates with a height of 15cm
Fluoride ion production: in order
Fluoride ion production: methoxyflurane > sevoflurane > enflurane > isoflurane > desflurane.
The _________ allows for comparison of two populations with respect to a single variable with continuous data
The unpaired t-test allows for comparison of two populations with respect to a single variable with continuous data
Chemical stimuli that mediate the activation of peripheral nociceptors:
Chemical stimuli that mediate the activation of peripheral nociceptors include prostaglandins, substance P, calcitonin gene-related peptide, glutamate, bradykinin, protons, ATP, and proinflammatory cytokines, whereas spinal cord INHIBITION is mediated by opioids, γ-aminobutyric acid (GABA), and/or glycine.
Chemical stimuli that mediate the inhibition:
Chemical stimuli that mediate the ACTIVATION of peripheral nociceptors include prostaglandins, substance P, calcitonin gene-related peptide, glutamate, bradykinin, protons, ATP, and proinflammatory cytokines, whereas spinal cord INHIBITION is mediated by opioids, γ-aminobutyric acid (GABA), and/or glycine.
risk factors for bradycardia after succ administration:
Repeat administration (e.g. an additional dose given within five minutes of an initial dose) and young age are the greatest risk factors for bradycardia with succinylcholine use. Bradycardia with repeat administration is a result of myocardium being sensitized by metabolic products of succinylcholine.
Major independent preoperative risk factors for postoperative AKI following noncardiac surgery in patients with normal renal function include:
Major independent preoperative risk factors for postoperative AKI following noncardiac surgery in patients with normal renal function include age ≥ 59, BMI ≥ 32, chronic liver disease, COPD requiring chronic bronchodilator use, peripheral vascular occlusive disease, high-risk surgery (intrathoracic, intraperitoneal, or suprainguinal vascular surgeries or those involving large blood loss or fluid shifts), and emergency surgery.
IgA deficient patients are at risk for what following blood transfusion?
IgA deficient patients are at risk for anaphylactic response to IgA antigens in donor blood, as they may have anti-IgA antibodies from prior blood exposure or pregnancy. To avoid this reaction, these patients should receive washed red blood cells or blood from IgA deficient donors.
what anticholinesterase to pair with atropine for reversal?
edrophonium because similar onset of action (1 min) and duration (15-30 min)
prerenal urine sodium
less than 10
intrinsic urine sodium
greater than 20
postrenal urine sodium
greater than 40
prerenal BUN:Cr
greater than 20
most effective med at preventing PONV in pediatric patients
Ondansetron is the most efficacious pharmacotherapy to prevent PONV in pediatric patients.
TrueLearn Insight : Aprepitant is a neurokinin-1 (NK-1) receptor antagonist with similar efficacy to ondansetron in preventing early PONV and is significantly more effective at preventing late PONV (24-48 hours postop).
order the bioavailability of midaz by route of admin
The bioavailability of midazolam, at the above doses, from greatest to least is: intravenous > intramuscular > sublingual > intranasal > rectal > oral. Intravenous administration of a drug will offer 100% bioavailability through avoidance of the “first pass” effect.
SvO2 equation
The Fick equation reveals SvO2 = SaO2 - [VO2 ÷ (CO * Hgb * 1.36)]
Where: SvO2 = mixed venous oxygen saturation SaO2 = arterial oxygen saturation VO2 = total body oxygen consumption CO = cardiac output Hgb = hemoglobin concentration
normal SvO2
75%
ABG measured directly
In an arterial blood gas, pH, pO2, and pCO2 are all directly measured using the electrodes mentioned above. The HCO3 is calculated.
what electrodes measure oxygen
Clark, galvanic, and paramagnetic electrodes measure oxygen. Severinghaus electrode measures CO2. Sanz electrode measures pH.
what electrode measures CO2
Clark, galvanic, and paramagnetic electrodes measure oxygen. Severinghaus electrode measures CO2. Sanz electrode measures pH.
what electrode measures pH?
Clark, galvanic, and paramagnetic electrodes measure oxygen. Severinghaus electrode measures CO2. Sanz electrode measures pH.
aspirin overdose
symptoms:
initial metabolic derrangement
later metabolic derrangement
Aspirin overdose is very dangerous and can have significant physiologic effects. Initial symptoms are rather nonspecific and include tinnitus, nausea, and vomiting. Eventually, mental status changes and death may occur if the overdose is not treated promptly. Hyperpnea often occurs early in aspirin overdose and is a result of salicylates causing stimulation of the medullary respiratory area. This stimulation causes hyperventilation leading to respiratory alkalosis. Eventually, an aspirin overdose will lead to a metabolic acidosis in combination with a respiratory alkalosis. Hemodialysis may be indicated in an acute aspirin overdose.
PE Metabolic derrangement
Pulmonary embolism leads to a respiratory alkalosis. A pulmonary embolism causes a stimulation of pulmonary mechanoreceptors, and an increase in minute ventilation. A pulmonary embolism (PE) will cause an increase in the amount of dead space in the lungs. Oxygen diffuses more slowly than CO2 and therefore with an increase in minute ventilation PaCO2 will fall, and PaO2 will remain the same or slightly increase. Because pulmonary embolism often manifests without hypoxia, PE must be strongly considered in a hyperventilating patient before ascribing the cause of anxiety.
progesterone causes what metabolic derrangement
resp alkalosis
how does neuron action potential terminate?
A neuron action potential is terminated by membrane repolarization caused by the inactivation and then closing of voltage-dependent sodium channels and the opening of potassium channels that promote potassium efflux.
TrueLearn Insight: Local anesthetics block nerve impulse transmission by reversibly binding to the intracellular portion of the voltage-gated sodium channels and thereby preventing sodium ion influx.
Important side effects of amiodarone include:
Important side effects of amiodarone include bradycardia, hypotension, hypothyroidism, life-threatening hyperthyroid storm, pulmonary toxicity (with a pulmonary fibrosis appearance), prolonged QT interval, and elevated liver function markers.
amiodarone half life
45 days
prostacycline does what to vessels
vasodilate
renal failure paralytics
Of the commonly used NMBs, only succinylcholine and cisatracurium have minimal renal excretion and predictable durations of action in patients with renal failure.
test for synthetic fxn of liver
The PT is the best test to measure synthetic function of the liver. The PT is often elevated 1.5 times normal when severe liver disease is present. The PT measures the clotting time of the extrinsic pathway involving factor VII, which has the shortest half-life of the clotting factors.
TrueLearn Insight : Mnemonic: WEPT for Warfarin, Extrinsic, PT. Mnemonic for Vitamin K dependent factors: 1972 for 10, 9, 7, 2.
what enzymes does st johns wort affect
INCREASES 3A4 and 2C9 (increased metabolism of drugs)
Clopidogrel
is a prodrug activated by the 2C19 system
Cyclopentolate
Cyclopentolate is an anticholinergic drug often used during ocular surgery to induce mydriasis that can lead to CNS toxicity, including convulsions, if absorbed systemically.
TrueLearn Insight : Cessation of ocular globe manipulation is the first step in treating life-threatening bradycardia caused by the oculocardiac reflex during ocular surgery.
how do NSAIDs affect the kidney
Prostaglandins typically vasodilate afferent glomerular arterioles leading to increased glomerular capillary perfusion pressure. Nonsteroidal anti-inflammatory drugs are potentially nephrotoxic because they inhibit the production of prostaglandins. The nephrotoxic effects of NSAIDs may be exaggerated in hypovolemic patients.
The following diagnoses should be considered in patients with a large R wave in lead V1:
The following diagnoses should be considered in patients with a large R wave in lead V1:
1) Right ventricular hypertrophy
2) Posterior wall MI
3) Wolff-Parkinson-White syndrome
4) Muscular dystrophy
5) Right atrial enlargement
6) Right ventricular strain with ST-T wave abnormalities
What is preserved in anterior spinal artery syndrome?
In anterior spinal artery syndrome, there is loss of motor, temperature, and pain function. Proprioception and vibratory senses are preserved.
biochemical results of positive pressure ventilation
Biochemically, positive pressure ventilation induces cytokine release which can cause endothelial activation, increase vascular permeability, and result in apoptosis of renal epithelial cells
neurohormonal effects of positive pressure ventilation
Positive pressure ventilation also results in an increase in sympathetic nervous system output which secondarily results in an increase in renin release through beta-1 receptor stimulation with resultant release of angiotensin-2 and aldosterone. This results in vasoconstriction with salt and water retention which can decrease urine output. There is also an increase in the release of ADH (also seen with surgical stress) which increases free water reabsorption and decreases urine output, however this is a minor component. Lastly, there is a decrease in atrial natriuretic peptide which decreases natriuresis and vasodilation.
Methemoglobin
Methemoglobin (MetHb) is an altered state of hemoglobin (Hb) where the ferrous (Fe2+) form of heme is oxidized to the ferric form (Fe3+). Anemic hypoxia and cyanosis develop since MetHb does not bind oxygen and therefore cannot transport it to tissues for use.
What can cause methemoglobinemia?
Acquired methemoglobinemia occurs after exposure to substances that oxidize normal Hb faster than the enzyme methemoglobin reductase can reduce it. Examples include some local anesthetics (notably benzocaine and prilocaine), certain antibiotics (e.g. dapsone, sulfonamides, and trimethoprim), metoclopramide, nitrates, and nitrites.
Lab for methemoglobinemia
Arterial blood gas analysis with co-oximetry is therefore critical for assessment of MetHb levels and to guide/follow treatment since co-oximetry directly measures the amount of MetHb present and determines the true SaO2.
SpO2 value and SaO2 value on ABG when have methemoglobinemia
The presence of MetHb forces two-wave pulse oximetry to falsely display an SpO2 of 85-88% regardless of true SaO2 and will cause the calculated SaO2 on an ABG to be falsely high. In general, PaO2 values are unaffected by MetHb and will increase appropriately when supplemental oxygen is given.
What can you use to anticoagulate someone with HIT?
Direct thrombin inhibitors include argatroban, bivalirudin, lepirudin, and desirudin which are approved for use in HIT. Dabigatran is an oral direct thrombin inhibitor.
treatment for COPD with auto-PEEP (breath stacking)
Treating auto-PEEP with extrinsic PEEP seems counterintuitive, however in patients with airflow obstruction external PEEP can be used to decrease the work of breathing and relieve dyspnea. The added PEEP will stent the collapsed airways open, increasing expiratory flow and reducing auto-PEEP. This does not help all patients with auto-PEEP due to airway obstruction and should be instituted slowly.
At 1.0 MAC of isoflurane, cardiovascular effects include:
At 1.0 MAC of isoflurane, cardiovascular effects include increased heart rate (10-15 beats/min), decreased SVR and blood pressure, and minimal changes in CVP. Respiratory effects include a mild reduction in minute ventilation, a reduced tidal volume, and an increased respiratory rate.
Respiratory effects of 1 MAC of isoflurane
Isoflurane at 1.0 MAC decreases the response to PaCO2, increases respiratory rate, and reduces tidal volume. These effects combine to yield a mild reduction in minute ventilation.
First sign of lidocaine CNS toxicity
Central nervous system toxicity is first noted by circumoral and tongue numbness.
Areas of regional anesthesia from highest to lowest vascularity include: intravenous > tracheal > intercostal > caudal/paracervical > epidural > brachial plexus > sciatic/femoral > spinal > subcutaneous.
Side effects of neostigmine
Neostigmine, however, causes an increase in acetylcholine throughout the body with several resulting side effects. The side effects are generally those related to the activation of the parasympathetic nervous system. They are as follows:
Cardiac: bradycardia, hypotension
Pulmonary: bronchospasm, increased respiratory secretions
GI: increased peristalsis, increased salivation and GI secretions
Ophthalmic: miosis, decreased intraocular pressure
mydriasis
pupil dilation
miosis
pupil constriction
nicotinic receptors
present on skeletal muscle and autonomic ganglia
muscarinic receptors
end organ receptors on salivary/gastric glands, smooth muscle [bronchial, gastrointestinal, bladder, and vascular], and the SA and AV nodes of the heart
NMBDs block which acetylcholine receptors
Neuromuscular blockers only block the nicotinic receptors on the skeletal muscles, thereby causing paralysis.
max neostigmine dose
The maximum recommended dose of neostigmine is 0.08 mg/kg up to a maximum of 5 mg in an adult.
which vitamin K dependent factor has shortest half life
Factor VII has the shortest half-life of the vitamin K dependent factors and is an early and reliable measure of potentially severe liver dysfunction.
6 HOURS!
what is fibrinogen
factor I
which factor is Christmas factor
IX
Other name for factor VII
Proconvertin
Perioperative hyperglycemia has been associated with:
Perioperative hyperglycemia has been associated with immunosuppression, increased infections, osmotic diuresis, delayed wound healing, delayed gastric emptying, sympatho-adrenergic stimulation, and increased mortality. In addition, it reduces skin graft success, exacerbates brain, spinal cord, and renal damage by ischemia, worsens neurologic outcomes in traumatic head injuries, and is associated with postoperative cognitive dysfunction following CABG.
non-hemolytic febrile transfusion reaction
Non-hemolytic febrile transfusion reaction is the most common blood reaction to occur. Non-hemolytic reaction is defined as a temperature increase of greater than 1 degree Celsius without concurrent hemolysis. A non-hemolytic febrile transfusion reaction occurs because recipient antibodies cause lysis of donor leukocytes found in the red cell transfusion product.
which opioid does not cause biliary spasm
Butorphanol, unlike most opioids, does not cause biliary spasm as it does not cause sufficient sphincter of Oddi contraction to increase pressure in the common bile duct.
3 ways to use a circle system
The circle system can be used three different ways depending on the fresh gas flow.
- Semi-open system: high fresh gas flows with no rebreathing
- Semi-closed system: lower fresh gas flows with some rebreathing
- Closed system: fresh gas flow matches patient consumption with complete rebreathing
In order to prevent rebreathing of carbon dioxide in a traditional circle system, three requirements must be fulfilled:
In order to prevent rebreathing of carbon dioxide in a traditional circle system, three requirements must be fulfilled:
- A unidirectional valve must be positioned between the patient and both the inspiratory and expiratory limbs (A, B).
- Fresh gas flow cannot come into the circle system between the patient and the expiratory valve (C).
- The APL valve cannot be positioned between the patient and the inspiratory valve
To pass a negative pressure lak test
A suction bulb attached to the common gas outlet must remain collapsed for at least 10 seconds to pass a negative pressure leak test
A negative pressure leak test is used to test the integrity of the low-pressure circuit which includes all components from the flow control valves to the common gas outlet. Leaks in this circuit can cause hypoxia and awareness. The negative pressure leak test allows differentiation between leaks in the machine and leaks in the breathing system.
signs of hypocalcemia
Citrate is found in blood storage preservatives where it acts as an anticoagulant. Once transfused, large amounts of citrate reversibly bind (chelate) ionized calcium which may lead to hypocalcemia in the setting of rapid transfusion and liver dysfunction. This leads to hypotension,
narrow pulse pressure,
increased LVEDP,
prolonged QT interval,
narrowed QRS,
and flattened T waves.
Supplemental calcium administration is appropriate in this setting. Unlike CPDA, the anticoagulant EDTA is not commonly used clinically since it irreversibly binds calcium.
LMA can cause nerve palsy of what nerves?
Lingual nerve, recurrent laryngeal nerve, and hypoglossal nerve palsies have been reported following LMA use. Risk factors include overinflation of a small-fitting cuff, prolonged operative times (>2-4 hours), lidocaine lubrication, difficult insertion, use of nitrous oxide, and cervical joint disease.
The top three causes of death associated with blood product transfusion since the year 2000 in the United States are
The top three causes of death associated with blood product transfusion since the year 2000 in the United States are 1) TRALI, 2) HTRs (non-ABO > ABO), and 3) Infection and TAS.
Insulin and glucagon signaling pathways in hepatocytes
Insulin and glucagon utilize the cAMP signaling pathway during signal transduction within the hepatocyte. Insulin decreases intracellular cAMP whereas glucagon increases this second messenger.
The major landmark for performing a stellate ganglion block is
The major landmark for performing a stellate ganglion block is Chassaignac tubercle, which is the transverse process of C6.
TrueLearn Insight : The cervical levels on an AP radiograph of the neck can be determined by identifying the vertebra associated with the first rib, which is the first thoracic vertebra.
What percentage of N2O tank is left when the pressure starts to drop
25%
Radiation intensity (exposure) with respect to distance
Radiation intensity (exposure) with respect to distance decreases according to the inverse square law: I ∝ 1 / r^2. Accordingly, doubling the distance from a radiation source decreases exposure by a factor of 4.
Pulmonary vascular resistance is highest at
Pulmonary vascular resistance is highest at extremes of lung volumes. It is lowest at FRC while increasing or decreasing lung volumes beyond FRC results in an increase in PVR.
Mechanism and location of action of HCTZ
Hydrochlorothiazide is a diuretic that works by blocking the Na/Cl co-transporters in the distal convoluted tubules of the kidney, thereby decreasing Na and Cl reabsorption.
HCTZ electrolyte disturbances
Hydrochlorothiazide has the potential to cause several electrolyte disturbances. Increased excretion of chloride can lead to a hypochloremic metabolic alkalosis and increased excretion of sodium can lead to hyponatremia. It also increases potassium excretion leading to hypokalemia. Hydrochlorothiazide can also directly inhibit calcium excretion leading to hypercalcemia.
Spironolactone mech
blocks aldosterone receptor sites in the distal convoluted tubule
Furosemide mechanism and location of action
Furosemide, a loop diuretic, inhibits water reabsorption in the nephron by blocking the sodium-potassium-chloride cotransporter (NKCC2) in the thick ascending limb of the loop of Henle.
Principle of increasing peak vs plateau pressure
Both peak inspiratory and plateau pressure increase when elastic resistance (compliance) increases. Only peak inspiratory pressure increases when airway resistance increases. Bronchospasm, for example, will cause an increase in peak inspiratory pressure with a mostly unchanged plateau pressure.
A capnogram from a patient with a single lung transplantation due to COPD will show a
A capnogram from a patient with a single lung transplantation due to COPD will show a “double peak” pattern reflecting the difference in function between the healthy transplanted lung and the diseased native lung. The rapid initial exhalation from the healthy, transplanted lung produces the first peak while the slower rate of rise of exhaled CO2 from the diseased, obstructed lung produces the second peak.
A double lung transplant in a patient with COPD should reveal what on capnography
A double lung transplant in a patient with COPD should reveal a normal-appearing capnography tracing assuming the transplanted lungs are healthy and no rejection has developed.
An incompetent inspiratory valve capnograph
An incompetent inspiratory valve allows exhaled gas (containing CO2) to enter the inspiratory limb of the breathing circuit during expiration. Therefore, the CO2-containing gas is inspired by the patient during the following inspiration. This extends the expiratory alveolar plateau (phase 3-4 in Figure 1). A decrease in CO2 occurs after the extended plateau and represents sampling of CO2-free gas that arrived from further proximal in the inspiratory limb. Thus the inspiratory downstroke (phase 4-1 in Figure 1) is significantly blunted and the inspiratory phase is shortened. See Figure 3, below. Note, during the latter portion of inhalation, the CO2 concentration may or may not reach zero, depending on fresh gas flow (FGF).
A capnogram tracing with incompetent expiratory valve
A capnogram tracing does not return to zero during inspiration when the expiratory valve is incompetent. This is due to rebreathing of exhaled gases from the expiratory limb in reverse direction and also results in a mildly elevated expiratory segment. Assuming the patient is healthy, the shape of the tracing will be otherwise normal. Note, this capnograph may also occur in the setting of exhausted carbon dioxide absorbent.
A needle passes through the ___________________ prior to entering the epidural space when performing a caudal epidural.
The sacrococcygeal ligament covers the opening of the sacral hiatus. Landmarks for caudal blockade include the triangle with vertices at the posterior superior iliac spines and the sacral hiatus. The sacral hiatus lies directly superior to the coccyx bone. The sacral hiatus is created by the non-union of the S4 and S5 lamina. In infants, the dural sac extends to S3/S4 and makes dural puncture more likely. In adults, the sacrococcygeal ligament becomes heavily calcified making caudal anesthesia difficult.
2-Chloroprocaine onset time
2-Chloroprocaine has the fastest onset of action time among commonly used epidural local anesthetics at 6-12 minutes. It has the shortest duration of action of all the local anesthetics.
Trendelenburg position effects on respiration
Trendelenburg position reduces FRC, TLC, lung compliance, and chest wall compliance. Abdominal contents are shifted cephalad, which may potentially relocate the end of a fixed ETT into the right mainstem bronchus
MI timeline for elective non-cardiac surgery
Patients who have an old myocardial infarction (MI) may proceed to surgery without additional specific evaluation and treatment (D).
An old MI is defined as occurring more than 30 days prior. An acute MI is defined as occurring in the past 7 days and a recent MI is defined as occurring between 7 and 30 days prior. Both acute and recent MIs (as well as unstable angina) define the unstable coronary syndromes. These place patients at a much higher risk for perioperative cardiac events and these patients should be evaluated further prior to elective non-cardiac surgery. Active cardiac conditions mandate further preoperative evaluation and treatment.
Mobitz type II AV block in pre-op
further eval and treatment prior to proceeding with surgery
common side effects of fospropofol
The most common side effects of the water-soluble propofol prodrug fospropofol are paresthesias (typically perianal or genital) and genital pruritus. Due to its slower onset of action, the incidence of respiratory depression, apnea, and hypotension are lower with fospropofol compared to propofol.
supraclavicular block: blocks which nerves? misses which nerve? where is it done?
done in medial axillary fossa
Supraclavicular block is a common brachial plexus nerve block used for surgery distal to the shoulder as it blocks the musculocutaneous, radial, ulnar, and median nerves but fails to block the medial aspect of the upper arm supplied by the intercostobrachial nerve (not a branch of the brachial plexus) and therefore supplementation of the supraclavicular block with an intercostobrachial nerve block would be required to prevent tourniquet pain.
Block which nerves to prevent coughing during awake intubation
Coughing during awake intubation can be prevented by blockade of the superior laryngeal nerve and recurrent laryngeal nerve. The glossopharyngeal nerve also provides airway innervation but is involved in the gag, not the cough reflex.
Cholinesterase inhibitors affect on non-depolarizers and depolarizers
Cholinesterase inhibitors increase the amount of acetylcholine available and therefore make nondepolarizing muscle blockade more difficult. In contrast, cholinesterase inhibitors partially inhibit pseudocholinesterase and therefore potentiate a depolarizing blockade.
chronic phenytoin use (and carbamazepine) results in ________ to a nondepolarizing blockade
chronic phenytoin use (and carbamazepine) results in resistance to a nondepolarizing blockade. Acute phenytoin therapy can augment neuromuscular blockade.
The sympathetic cardiac innervation. Where does it originate and what receptors does it include?
The sympathetic cardiac innervation originates from T1-T4 and is associated with α1, β1, and β2 adrenergic receptors.
TrueLearn Insight : A left stellate ganglion block can be performed to reduce the risk of arrhythmias associated with long QT syndrome.
What three adrenergic receptors are involved with sympathetic cardiac innervation and what do they do?
All three adrenergic receptors are involved with sympathetic cardiac innervation:
α1: Positive inotropy
β1: Positive chronotropy, dromotropy (conductivity of a nerve), lusitropy (myocardial relaxation), and inotropy
β2: Positive chronotropy > inotropy
SECOND main mechanism of heat loss in OR
Redistribution of heat from the core to the periphery is the largest contributor to the initial reduction in core temperature during general anesthesia. Prevention or reduction of this can be accomplished by pre-warming the patient’s extremities prior to the induction of general anesthesia. Radiation is the main mechanism for patient heat loss in the operating room following this initial redistribution of heat.
ESRD and dilaudid
Hydromorphone accumulates in patients with renal failure, so smaller doses are necessary. In addition, a toxic metabolite, hydromorphone-3-glucuronide, can accumulate. Like normeperidine, it also has neuroexcitatory and pro-convulsant properties.
ESRD and remifentanil
because remifentanil is metabolized independent of the liver and kidneys, it is considered ideal for patients with renal failure. Remifentanil is usually administered as a continuous infusion due to its short elimination half-life (0.17-0.33 hours) and steady context-sensitive half-time regardless of infusion duration. Methadone also needs little adjustment in patients with renal disease.
ESRD and fentanyl
Fentanyl is relatively safe when used in patients with end stage renal disease (ESRD) because of its rapid redistribution, lack of metabolites, and unchanged free fraction.
ESRD and methadone
Methadone also needs little adjustment in patients with renal disease
ESRD and ketorolac
Ketorolac is a nonsteroidal anti-inflammatory drug which prevents the synthesis of prostaglandins. Inhibition of PG synthesis can affect renal glomerular blood flow by causing vasoconstriction of the afferent arterioles of the glomeruli. This can cause or worsen preexisting renal failure. Ketorolac also reversibly inhibits the cyclooxygenase (COX) enzyme which prevents the formation of thromboxane from arachidonic acid. Thromboxane promotes platelet aggregation and its absence can lead to increased bleeding.
ESRD and meperidine
Meperidine is a synthetic opioid commonly used for pain management and treatment of shivering in the postoperative period. A toxic metabolite of meperidine, normeperidine, accumulates in patients with renal failure. Normeperidine has neuroexcitatory properties and can precipitate seizures.
ESRD and morphine
Morphine should be used with caution in patients with renal failure due to the accumulation of an active metabolite, morphine-6-glucuronide. Morphine-6-glucuronide can lead to prolonged sedation and respiratory depression.
magnesium mechanism
calcium channel antagonist
treatment of hypermagnesemia
Treatment of hypermagnesemia is IV calcium.
How adjust dose of non-depolarizing NMBD in setting of hypercalcemia-associated hyperparathyroidism?
Hypercalcemia antagonizes the effects of non-depolarizing neuromuscular blockers and higher doses may be required to obtain the desired effect.
Pupillary sign of awareness
Clinical signs of awareness include autonomic signs such as hypertension and tachycardia, pupillary dilation, lacrimation, sweating, and patient movement
How adjust dose for neo/glyco reversal in ESRD?
The durations of action of commonly-used anticholinesterases and anticholinergic drugs for reversal of nondepolarizing neuromuscular blockade are prolonged in the setting of CKD and ESRD. However, no dosage alterations are required and the normal maximum recommended doses still apply.
Name 3 NMBDs that have minimal to no reliance on renal excretion
TrueLearn Insight : Succinylcholine, mivacurium, and cisatracurium have minimal to no reliance on renal excretion and accordingly, their durations of action are not significantly prolonged in the setting of ESRD.
CBF change by how much for every 1 mmHg change in PaCO2?
Hyperventilation leads to decreased CBF by decreasing PaCO2. CBF changes 1-2 mL/100 g/min per every 1 mmHg change in PaCO2.
Denervation disorders that cause AChR upregulation
Multiple sclerosis, Guillain-Barre, ALS
(Myasthenia gravis (MG), Lambert-Eaton myasthenic syndrome (LEMS), and chronic renal failure do not lead to upregulation of nicotinic acetylcholine receptors)
Risk factors for post op ulnar nerve injury
How determine timing?
Can nerve conduction studies evaluate motor AND sensory deficits?
Postoperative ulnar nerve injury is the most common form of perioperative peripheral neuropathy. It occurs more commonly in males and very thin or obese patients. Ulnar neuropathy is typically transient but can persist and cause morbidity and disability. Nerve conduction studies are beneficial in evaluating both motor and sensory deficits. Electromyography can help determine the timing of the nerve injury.
Effects of sodium bicarb admin
Sodium bicarbonate administration is associated with transient increases in PaCO2, EtCO2, and intracranial pressure. Administration causes transient decreases in serum calcium and potassium. Sodium bicarbonate can also cause hypotension due to hypocalcemia, ventricular depressant effects, and redistribution of blood to the pulmonary vasculature.
Hepatic protein synthesis is best assessed by measuring…
Hepatic protein synthesis is best assessed by measuring coagulation factors.
How to decrease pain with propofol injection
Mixing propofol with lidocaine has been shown to decrease the stability of the propofol emulsion and may cause pulmonary embolism. The FDA recommends against mixing propofol with any other therapeutic medications prior to administration. The most effective methods to reduce pain are propofol injections using an antecubital vein and a modified Bier block prior to injection.
what is efficacy
Efficacy is the maximum effect of a drug. It does not depend on dose. Potency is the relative dose required to achieve a given effect and is related to receptor affinity. The potency of a partial agonist may be higher than that of a full agonist. The efficacy of a partial agonist cannot be higher than that of a full agonist.
what is potency
Efficacy is the maximum effect of a drug. It does not depend on dose. Potency is the relative dose required to achieve a given effect and is related to receptor affinity. The potency of a partial agonist may be higher than that of a full agonist. The efficacy of a partial agonist cannot be higher than that of a full agonist.
Which of the following topical ocular drugs can potentiate the effects of succinylcholine?
The use of topical echothiophate eye drops for greater than 1 month can be associated with up to a 95% decrease in function of plasma butyrylcholinesterase. Normal activity returns within 4-6 weeks after discontinuation. Succinylcholine administration during this time may result in prolonged neuromuscular blockade.
Cyclopentolate
Cyclopentolate is a topical anticholinergic ocular drug used to induce mydriasis for ocular procedures. Systemic absorption can occur and lead to central nervous system (CNS) signs and symptoms of anticholinergic toxicity. Signs and symptoms include dysarthria, tachycardia, disorientation, psychosis, and convulsions.
How do benzos potentiate neuromuscular blockade?
Benzodiazepines have centrally acting muscle-relaxing properties and potentiate the effects of GABA
how does gaba receptor work?
GABA is an inhibitory neurotransmitter that controls the state of chloride ion channels. Activation of the chloride channel results in neuronal hyperpolarization which will act to drive the membrane potential away from threshold potential. In other words, hyperpolarization will decrease the ability for a membrane potential to occur. Benzodiazepines exert their effects selectively at the GABA receptors in the central nervous system. The highest density of benzodiazepines receptors are in the olfactory bulb, cerebral cortex, cerebellum, hippocampus, substantia nigra and inferior colliculus. Spinal cord benzodiazepine receptors may play an important role in analgesia. There are also peripheral binding sites for benzodiazepines which are not associated with the GABA receptors; their function remains unknown at this time.
how much does the height of the a-line transducer change the reading?
A 10 cm change in height will alter the pressure reading by 7.5 mm Hg. Raising the transducer (lowering the patient) lowers the pressure reading. Lowering the transducer (raising the patient) increases the pressure reading.
TrueLearn Insight : A mnemonic that can help with this question is pH 15 20, to remind you that pressure of 15 mmHg equals a height of 20 cm.
percent of receptor stimulation correlated to twitches
When assessing the degree of neuromuscular blockade using TOF stimulation after nondepolarizing NMBD administration:
1 palpated twitch indicates >90% suppression.
2 palpated twitches indicate 80-90% suppression.
3 palpated twitches indicate 70-80% suppression.
4 palpated twitches indicate up to 65-75% suppression.
Palpation of twitches using TOF testing cannot detect the percentage of receptors bound at < 65%.
1mL of liquid anesthetic is converted to ___ml vapor
One milliliter of liquid anesthetic is converted to approximately 200 mL vapor at room temperature. A shortcut for calculating the volume of liquid anesthetic consumed in one hour is: Liquid volatile anesthetic (mL/hr) ≈ 3 * FGF (L/min) * % anesthetic vapor.
formula for calculating vol of LIQUID anesthetic consumed in one hour
One milliliter of liquid anesthetic is converted to approximately 200 mL vapor at room temperature. A shortcut for calculating the volume of liquid anesthetic consumed in one hour is: Liquid volatile anesthetic (mL/hr) ≈ 3 * FGF (L/min) * % anesthetic vapor.
what characteristic makes CO2 absorbent more likely to generate CO
New generation carbon dioxide absorbents do not contain strong bases and as a result, are much less likely to react with volatile anesthetics and generate carbon monoxide.
Vaporizer output for sevo: what fraction of input?
A variable bypass vaporizer is being used to administer sevoflurane (saturated vapor pressure = 160 mm Hg) to a patient at sea level. A fresh gas flow of 2.5 L/min of 100% oxygen is being used, of which, 100 mL passes through the vaporizer chamber. What is the approximate sevoflurane concentration being delivered to the patient?
Vaporizer output for sevoflurane is approximately 1/4th the input.
So, 1/4 of 100 mL is ~25 mL, which is 1% of the 2.5 L/min fresh gas inflow.
vaporizer output for iso: what fraction of input?
1/2 of what goes through the vaporizer chamber
First alarm to detect hypoxic mixture
The oxygen analyzer will be the first device to detect a hypoxic mixture in the event of a pipeline crossover or mix-up where oxygen is replaced. A key step in the management of a pipeline supply issue is disconnecting the pipeline supply gases.
Management steps for loss of pipeline pressure
The management steps for loss of pipeline pressure are the same as those for pipeline crossover:
1) Open the emergency oxygen cylinder fully (not just the three or four quick turns used for checking).
2) Disconnect the pipeline connection at the wall because something is wrong with the oxygen pipeline.
3) Ventilate by hand with the anesthesia breathing circuit, rather than with the mechanical ventilator (which may use cylinder oxygen for the driving gas if the pipeline is unavailable).
explain TOF ratio and fade
Train of four (TOF) stimulation administers four supramaximal stimuli every 0.5 seconds (2 Hz) which cause the muscle to contract. The fourth twitch amplitude is divided by the first twitch amplitude (4th / 1st) to give the TOF ratio. The term “fade” is used at times and refers to the percentage less than 1.0, where 1.0 would be no fade (4th equal to 1st). For example, if the 4th twitch were 75% as high as the first twitch, the TOF ratio would be 75% and there would be 25% fade.
what is. double burst stimulation
Double burst stimulation (DBS) was developed to help improve tactile detection of residual block and it is superior to TOF when manual detection is required. There are many ways DBS can be applied. Most commonly, three 0.2 msec bursts at a 50 Hz frequency are applied followed 750 msec later by an identical burst. The muscle responses are of greater magnitude than those elicited by TOF allowing more accurate visual and tactile assessment. In normal muscle the response will be two sets of contractions of equal strength. With neuromuscular blocking agents, the second response is weaker than the first and corresponds to the typical TOF fade. DBS does not replace objective monitors and should be used as an adjunct.
train of 4 monitoring vs double burst monitoring
TOF is less painful and generally does not influence subsequent monitoring of neuromuscular block. Both TOF and DBS require similar technology. DBS does not more accurately predict neuromuscular function; it just allows better tactile distinction. Objective TOF monitoring (e.g. acceleromyography) is more accurate than DBS and is the preferred method for monitoring neuromuscular blockade. Every patient that receives a neuromuscular blocking agent, including succinlycholine, should have neuromuscular monitoring with a peripheral nerve stimulator.
what wavelength does deoxyhemoglobin absorb
A mnemonic to help recall light absorption by wavelength is SeXy DARLing: at SiX hundred wavelength, Deoxyhemoglobin Absorbs Red Light.
what dyes interfere with pulse ox
Certain dyes such as methylene blue, indocyanine green, indigo carmine, nitrobenzene, and lymphazurin/isosulfan blue are blue or blue-green dyes that absorb light at 660 nm significantly more than at 940 nm.
First stage regulator
Oxygen regulators are present in anesthesia machines to help ensure proper oxygen delivery and backup. The first-stage regulator will shut off the lower pressure oxygen cylinder tanks when the higher-pressure oxygen pipeline is sensed. The second-stage regulator, if present, will decrease pressure to slightly above atmospheric to ensure smooth constant flow of gases.
2nd stage regulator
Oxygen regulators are present in anesthesia machines to help ensure proper oxygen delivery and backup. The first-stage regulator will shut off the lower pressure oxygen cylinder tanks when the higher-pressure oxygen pipeline is sensed. The second-stage regulator, if present, will decrease pressure to slightly above atmospheric to ensure smooth constant flow of gases.
Infrared spectrometry can analyze what gases?
Infrared spectrophotometry is used to analyze polar, asymmetric, polyatomic gases such as CO2, volatile agents, and N2O. It operates on the principle that the amount of infrared light absorbed at a specific wavelength is proportional to the partial pressure of the gas analyzed because absorption will be greater with a greater amount of gas molecules. Intensity of IR light detected will therefore be inversely proportional to the amount of gas in the sample. O2, N2 (nitrogen), and xenon cannot be analyzed in this manner.
Who requires stress dose steroids?
Patients who were on a corticosteroid regimen of > 10 mg prednisone daily but stopped < 3 months prior to surgery should receive perioperative stress-dose steroids to prevent hemodynamic instability from an adrenal crisis.
Additional perioperative steroids are not required in patients taking high-dose steroids for immunosuppression since these doses are already supraphysiologic.
Shortest half life of all currently used benzos?
Flumazenil has the shortest elimination half life of all currently used benzodiazepines, which makes recrudescence of sedation after a single administration of flumazenil likely.
Note that although flumazenil is generally considered a benzodiazepine antagonist, it exhibits a partial agonist effect. In one study, propofol was potentiated by giving high doses of flumazenil, suggesting flumazenil has a mixed or partial agonist effect.
Hypothalamus
The hypothalamus is comprised of a large number of distinct nuclei that are responsible for numerous homeostatic functions including, but not limited to: control of blood flow, regulation of energy metabolism, regulation of reproductive activity, and coordinating responses to threatening conditions.
preoptic anterior hypothalamus
The hypothalamus is comprised of a large number of distinct nuclei that are responsible for numerous homeostatic functions. The preoptic anterior hypothalamus plays a key role in temperature homeostasis and thermoregulation. The medial tuberal hypothalamus contains neurons that extend into the posterior pituitary and secrete vasopressin and oxytocin.
medial tuberal hypothalamus
The hypothalamus is comprised of a large number of distinct nuclei that are responsible for numerous homeostatic functions . The preoptic anterior hypothalamus plays a key role in temperature homeostasis and thermoregulation. The medial tuberal hypothalamus contains neurons that extend into the posterior pituitary and secrete vasopressin and oxytocin.
2 other names for artery of Adamkiewicz
The great radicular artery (aka arteria radicularis magna or artery of Adamkiewicz) originates from the aorta between the T9 and T12 vertebral segments in 75% of the population.
What does the artery of Adamkiewicz do?
The great radicular artery supplies the majority of blood to the lower anterior portion of the spinal cord responsible for motor function. Therefore, during aortic reconstruction, interruption of this blood supply can potentially lead to irreversible spinal cord damage, paraplegia, and loss of bowel and bladder function, a condition referred to as ASA syndrome.
Posterior spinal cord does what
Proprioception and sensation
Lasix metabolic derrangement
Furosemide administration can cause a hypokalemic-hypochloremic metabolic alkalosis secondary to potassium excretion and a contraction alkalosis.
Thiazide metabolic derrangement
same as lasix
hypokalemic-hypochloremic metabolic alkalosis
med to correct hypokalemic-hypochloremic alkalosis
acetazolamide
Acetazolamide is a carbonic anhydrase inhibitor. It is a commonly used diuretic that causes noncompetitive inhibition of the carbon anhydrase enzyme. This enzyme usually catalyzes the reaction between water, carbon dioxide, carbonic acid, and bicarbonate. Inhibition of this enzyme causes an increase in renal bicarbonate with a resultant alkalization of the urine. Acetazolamide may cause a mild hyperchloremic metabolic acidosis due to bicarbonate excretion. It is especially important in patients with chronic hypercapnia as alkalemia can further depress ventilation. Acetazolamide may impair carbon dioxide elimination in patients with chronic obstructive pulmonary disease and should be used in caution with that patient population.
Met derrangement of potassium sparing diuretics
Potassium sparing diuretics act in the collecting ducts where they alter transport of sodium resulting in decreased sodium reabsorption. Additionally, the potassium excretion is inhibited resulting in decreased excretion and potassium sparing. A mild hyperchloremic metabolic acidosis can be observed when administering potassium-sparing diuretics. This is due to the lack of aldosterone effect on hydrogen ion secretion.
Effects of acute normoveolemic hemodilution
Acute normovolemic hemodilution causes decreased blood viscosity, decreased peripheral vascular resistance, increased cardiac output, and increased regional blood flow.
Epi dose in LAST
The dose of epinephrine in ACLS guided resuscitation of LAST should be reduced to < 1 mcg/kg per dose. Vasopressin use should be avoided.
TrueLearn Insight : Propofol should NOT be used in patients with cardiovascular instability from LAST. Although propofol exists as a lipid emulsion, the lipid content is too small to provide any significant clinical benefit. However, small doses of propofol may be considered for seizure suppression in patients without cardiac compromise when a benzodiazepine is not immediately available.
Initial steps for management of suspected or confirmed pulmonary aspiration of gastric contents in patients with an LMA:
Initial steps for management of suspected or confirmed pulmonary aspiration of gastric contents in patients with a LMA include increasing FiO2 to 100%, deepening anesthesia, and placing the patient in a head-down position. Suctioning should usually be performed and the severity of aspiration assessed using fiberoptic bronchoscopy. Additional measures such as intubating should be based on clinical judgment.
Electrolyte and acid-base abnormalities in alcoholics.
Electrolyte and acid-base abnormalities including hypokalemia, hypomagnesemia, hyponatremia, hyperuricemia, metabolic acidosis, and respiratory alkalosis are common in alcoholics.
LCA provides blood supply to what
The LCA provides blood supply to the apices of the LV and RV, the anterolateral LV, and the anterior two thirds of the interventricular septum.
RCA supplies blood to what
The RCA supplies the anterior and posterior RV, the RA, the upper atrial septum, the posterior third of the interventricular septum, and the inferior and posterior LV. Right-dominant hearts have an RCA which gives rise to the PDA and therefore supplies blood to the AV node but the PDA can arise from the LCx as well.
Bayes’ theorem
Bayes theorem is used to help develop preoperative testing algorithms by helping clinicians interpret testing results in light of the patient presentation and surgical procedure. Bayes theorem states that the post-test probability of a person having a disease is related to both the sensitivity and specificity of the test and the prevalence of the disease in the population. In other words, it describes the probability of an event, based on conditions that might be related to the event (conditional probability).
SpO2 reading in methemoblobinemia
Conventional pulse oximetry can neither detect MetHgb nor accurately measure SpO2 in the presence of elevated MetHgb levels. The standard two-wavelength pulse oximeters generally give measurements approaching 85% in the presence of high methemoglobin levels. In the setting of suspected methemoglobinemia, multi-wavelength co-oximetry should be used.
Treatment for methemoglobinemia in normal human
Methylene blue (1-2 mg/kg) is the primary pharmacologic treatment of methemoglobinemia. However, methylene blue can cause hemolysis in patients with G6PD-deficiency. Therefore ascorbic acid (vitamin C) is the treatment of choice of methemoglobinemia in the setting of G6PD-deficiency
Treatment for methemoglobinemia in G6PD-deficiency
Methylene blue (1-2 mg/kg) is the primary pharmacologic treatment of methemoglobinemia. However, methylene blue can cause hemolysis in patients with G6PD-deficiency. Therefore ascorbic acid (vitamin C) is the treatment of choice of methemoglobinemia in the setting of G6PD-deficiency
Pulse ox reading associated with use of methylene blue
A pulse oximetry value of 65% is associated with the use of methylene blue. Methylene blue transiently decreases the observed pulse oximetry reading in a dose dependent manner. Pulse oximetry reading approach 65% for roughly 10 minutes.
What opioid avoid if patient on MAO-I
Meperidine is a weak serotonin reuptake inhibitor and can therefore lead to serotonin syndrome if given to patients taking MAO inhibitors.
Differentiate serotonin syndrome from MH, neuroleptic malignant syndrome, anticholenergic toxicity
Clonus is the most important finding in confirming the diagnosis of serotonin syndrome. Ocular clonus is rarely seen in other conditions and can be elicited by having the patient fixate on a finger then rapidly moving it to midline.
The most accurate diagnostic criteria currently are the Hunter Toxicity Criteria Decision Rules. To meet diagnostic criteria, the patient must be on a serotonergic agent and have one of the following:
- Spontaneous clonus.
- Inducible clonus plus agitation or diaphoresis.
- Ocular clonus plus agitation or diaphoresis.
- Tremor plus hyperreflexia.
- Hypertonia plus temperature >38°C plus ocular clonus or inducible clonus.
For opioids, lipid solubility correlates with
Opioid duration of action is related to lipid solubility, with low solubility leading to longer action.
is morphine acid or base
weak base
An opioid with a pKa much lower than 7.4 will have a much _______ nonionized fraction in plasma than one with a pKa close to or greater than physiologic pH.
An opioid with a pKa much lower than 7.4 will have a much greater nonionized fraction in plasma than one with a pKa close to or greater than physiologic pH.
complication ass’d only with left sided central line placement
The thoracic duct drains into the venous system on the left, making chylothorax a complication of central line placement on the left side only. Pleural fluid analysis for triglyceride content helps to confirm a diagnosis of chylothorax.
TrueLearn Insight : Definitive diagnosis of chylothorax is made by analyzing the suspected chylous fluid (e.g. via thoracentesis). A high fat content, specifically triglycerides, and high T-lymphocyte count is diagnostic of chyle.
inhalation induction in adults
Inhalational anesthetic induction in adult patients typically preserves spontaneous ventilation and does not cause salivation. Stage II (excitation) is typically not seen. Pretreatment with benzodiazepines helps to improve the technique while pretreatment with opioids worsens the technique by potentially causing apnea.
tx for nausea in high spinal
Nausea and vomiting may be associated with neuraxial block in up to 20% of patients and atropine is almost universally effective in treating the nausea associated with high (T5) neuraxial anesthesia.
Unopposed parasympathetic (vagal) activity after sympathetic blockade causes increased peristalsis of the gastrointestinal tract, which can lead to nausea and is the primary mechanism behind nausea after spinal blockade. Atropine is an anticholinergic medication, thus is useful for treating nausea after high spinal blockade.
Differential blockade with local anesthetics
…and what order of fibers
Differential blockade with local anesthetics results in sympathetic blockade first, followed by pain/sensory blockade, then motor blockade last. This is (at least in part) explained by differential susceptibility of nerve fibers to local anesthetics being A-delta, A-gamma > lA-alpha, A-beta > C.
nerve C fiber
dull pain, touch, sympathetics, no myelin
a-delta
pain and temp, yes myelin
a-alpha
motor and prop, yes myelin
a-beta
pressure and touch, yes myelin
Sodium bicarb effects
Sodium bicarbonate can cause a number of physiologic alterations including increased preload, decreased left ventricular contractility, and increased hemoglobin affinity for oxygen. Sodium bicarbonate administration is also associated with intracranial hemorrhage, especially with rapid administration in infants, and increased lactate production.
Serum ionized calcium concentration is transiently decreased by sodium bicarbonate administration. Left ventricular contractility is subsequently depressed since it varies directly with serum ionized calcium concentration.
Splanchnic blood supply is controlled by…
Splanchnic blood supply is controlled by systemic blood pressure, cardiac output, and sympathetic tone. There is minimal contribution from the parasympathetic system.
Methadone
Opioid use for treating chronic pain is controversial. Methadone, however, is effective for chronic pain since in addition to its opioid analgesic effects, it has NMDA and serotonin reuptake antagonistic properties. The NMDA receptor antagonism also makes methadone effective for neuropathic pain.
Code without IV or IO access
If intravenous or intraosseous access cannot be established, epinephrine may be given through the endotracheal tube. The optimal dose is unknown but typically 2-2.5 times the intravenous dose is recommended. The dose should be diluted in 5-10 mL of sterile water or saline for endotracheal administration.
How does phenytoin affect NMBDs
Acute phenytoin administration potentiates the neuromuscular blockade of aminosteroid NDNBDs. Chronic phenytoin administration increases a patient’s resistance to the effects of NDNBDs and reduces their duration of action.
1) Increased metabolism via cytochrome P450 enzymes induction (this may explain why there is a clear effect with the aminosteroid NDNBDs, which rely on hepatic metabolism, but not with the benzylisoquinolines which undergo hepatic-independent Hofmann elimination and ester hydrolysis)
2) Increased postjunctional acetylcholine receptor density (the weak neuromuscular blocking properties of phenytoin, see below, results in postjunctional acetylcholine receptor upregulation)
3) Decreased sensitivity at the receptor sites
4) Increased end-plate anticholinesterase activity
What conditions upregulate ach receptors and what downregulate?
Conditions with cause an up-regulation of acetylcholine receptors include multiple sclerosis, burns, stroke, spinal cord injury, Guillain-Barre syndrome, prolonged immobility, and muscular dystrophies. The most common condition that causes a down-regulation of acetylcholine receptors is myasthenia gravis.
Epidural clonidine
Clonidine is an effective analgesic drug. It has a longer epidural effect duration than morphine. When given in combination with morphine, the analgesic effect is enhanced.
In one study, some patients who received clonidine had analgesia for up to one month
Na concentration of 5% albumin
Albumin solutions manufactured in the United States have a sodium concentration 145 +/- 15 mEq/L. A solution of 25% albumin should never be diluted with sterile water; normal saline or 5% dextrose in water are preferred diluents.
Effects of angiotensin II
Angiotensin II results in increased inotropy, chronotropy, catecholamine release, catecholamine sensitivity, aldosterone levels, vasopressin levels, and cardiac remodeling through AT1 receptors. ACE inhibitors and ARBs help to prevent the remodeling that occurs secondary to angiotensin II and are beneficial in congestive heart failure.
Anaphylactic reactions (IgE-mediated) to blood product transfusions classically occur in patients with
Anaphylactic reactions (IgE-mediated) to blood product transfusions classically occur in patients with hereditary IgA deficiency
