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
