Truelearn Flashcards
What causes overdamping of pressure waveform?
factors that increase the compliance of or resistance within the circuit—such as the addition of stopcocks, air bubbles, or distensible tubing
(MAP) is generally preserved
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What are the indication for hyperbaric oxygen therapy?
Gas-bubble disease (air embolism and decompression sickness)
Carbon monoxide poisoning
Infections (clostridial myonecrosis, other soft tissue necrotizing infections, refractory chronic osteomyelitis, intracranial abscess)
Acute tissue ischemia (crush injury, compromised skin flaps, central retinal artery or vein occlusion)
Chronic ischemia (radiation necrosis, ischemic ulcers)
Acute hypoxia (exceptional blood loss anemia when transfusion is unable to be given)
Acute thermal burn injury
Idiopathic sudden sensorineural hearing loss
Does adding Epi to buvipicaine prolong it’s effect? explain?
No. It improves quality of the analgesia. Epi decreases overall blood loss at site of admin, reducing systemic absorption by decreasing blood flow. This effect is more pronounced with short or intermediate acting local anesthetics.which tend to be more hydrophilic and less preferentially bound to tissue proteins.
By contrast, longer-acting local anesthetics such as bupivacaine exhibit durations of effect that are less responsive to vasoconstrictive additives such as epinephrine.
Indications for prophylactic antibiotics
Only patients who are undergoing dental procedures that “involve the manipulation of gingival tissue…periapical region of teeth, or perforation of the oral mucosa” are to be considered for prophylactic antibiotics
Only patients who are undergoing dental procedures that “involve the manipulation of gingival tissue…periapical region of teeth, or perforation of the oral mucosa” are to be considered for prophylactic antibiotics
Prosthetic cardiac valves, including transcatheter-implanted prosthetic valves
Patients with implanted prosthetic material, such as annuloplasty rings and artificial chordae tendineae
Patients with a history of infectious endocarditis
Patients with a history of unrepaired cyanotic congenital heart disease, including patients with a repair, but with a residual shunt or valvular regurgitation near an implanted patch or device
Patients with a history of cardiac transplantation who have a regurgitant valvular lesion due to a structurally abnormal valve
Most effective anesthetic technique for FIRST stage of labor
lumbar sympathetic block
- L2 and L3. A lumbar sympathetic block interrupts the transmission of pain impulses from the cervix and lower uterine segment to the spinal cord
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First stage - regular contractions with dilation of cervix <10cm
Second stage - cervix fully dilated >10cm. ends with birth of baby
third stage- placenta
Phosgene toxicity effects
colorless gas, smells like grass. causes significant pulmonary damage. Supportive care is tx. minimize inflammation
Bronchial cuff is clamped on double lumen tube. which lung is down?
Left lung
Bronchial cuff is suppose to be in left main bronchus. Tracheal cuff will close air to right lung
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What effect describes the hemoglobin oxygen dissociation curve caused by changes in carbon dioxide and pH?
Bohr effect
Chronic acid-base changes over 24-48 hours will alter levels of 2,3-DPG leading to a return to baseline of a shifted oxygen dissociation curve.
What is the Haldane effect?
Describes how oxygen concentrations determine hemoglobin’s affinity for carbon dioxide.
Ex: high oxygen concentrations enhance the unloading of carbon dioxide.
What principle described oxygen consumption relation to cardiac output?
Fick’s principle.relates oxygen consumption to cardiac output and the oxygen content difference between arterial and venous blood.
Ficks principle equation
VO2 (oxygen consumption) = Q (cardiac output) x (arterial -venous)O2
Q = HR \* SV SV = EDV - ESV
a = arterial O2 (left heart)
v = venous O2
difference in these is the oxygen delivered to tissues (which is used in the ETC)
What is the chloride effect?
chloride shift refers to the reaction in which bicarbonate is exchanged for a chloride ion across the red blood cell membrane. Bicarbonate is formed by the reaction of carbon dioxide and water via carbonic anhydrase (carbonic acid is initially formed but readily dissociates into bicarbonate and hydrogen ions).
how is CO2 transported in blood?
Dissolved CO2 in blood 7%
Binds to Hb 23%
covered to Bicarbonate in RBC (via carbonic anhydrase in RBC)
CO2 + H2O – HCO3 + H+
What chemical controls autoregulation of hepatic blood flow?
Adenosine.
Liver blood supply? Most oxygen content?
Hepatic artery 25% of blood flow, 50% oxygen supply
Splanchnic organs (intestines, stomach, pancreas, and spleen) 75% blood flow, 50% oxygen supply
Respritory changes in pregnancy
Decreased
- Residual volume
- Expritory reserve volume
- (FRC = ERV + RV) also decreased
Increased
- Inspritory reserve volume
- Tidal volume
Closing capacity unchanged
Vital capacity = ERV+ IRV + TV unchanged
What causes rightward shift in hemoglobin curve?
What causes leftward shift in hemoglobin curve?
A leftward shift increases hemoglobin’s affinity for oxygen and reduces tissue delivery.
The following factors cause a leftward shift of the P50 of hemoglobin:
• Hypothermia
• Carbon monoxide
• Fetal hemoglobin (Hgb F)
• Methemoglobin
• Hypophosphatemia (seen in the critically ill)
Late decelerations in pregnancy signify
Management of late decelerations in pregnancy, first step and later
Reposition pt in lateral position
IV fluids if hypotensive, leg raise
Discontinue uterotonic drugs
Administer tocolytic if sustained uterine contractions
Pt on low dose SQ Heparin (5000units BID or TID), how long to hold prior to neuroaxial procedure; when to restart after procedure, when to hold before removing neuroaxial catherter removal?
4-6 hours
restart immediatly after
hold 4-6 hours before removing catheter
Pt on HIGH dose SQ Heparin (7500-10,000units BID), how long to hold prior to neuroaxial procedure; when to restart after procedure, when to hold before removing neuroaxial catherter removal?
Hold 12 hours AND normal coagulation status
Avoid restarting if catheter in place
Restart immediatly after catheter removal
Pt on Theraputic dose SQ Heparin (>20,000units), how long to hold prior to neuroaxial procedure; when to restart after procedure, when to hold before removing neuroaxial catherter removal?
Hold for 24 hours AND normal coagulation status
Avoid restarting is catheter in place
Restart immediatly after removal
Pt on IV Heparin, how long to hold prior to neuroaxial procedure; when to restart after procedure, when to hold before removing neuroaxial catherter removal?
Hold 4-6 hours AND normal coagulation status
Restart 1 hour after procedure
hold 4-6 hours prior to removal of catheter
restart 1 hour after removal
Pt on prophylactic LMWH (daily), how long to hold prior to neuroaxial procedure; when to restart after procedure, when to hold before removing neuroaxial catherter removal?
Hold for 12 hours prior to procedure
restart after 12 hours if catheter in place
Hold 12 hours before removing catheter
restart after 4 hours AND no earlier than 12 hours
after catheter placement
Pt on Therapeutic LMWH, how long to hold prior to neuroaxial procedure; when to restart after procedure, when to hold before removing neuroaxial catherter removal?
Hold for 24 hours prior to procedure
Avoid restarting if catheter in place
Restart 4 hours AND no earlier than 24 hours after catheter placement
What is Heliox used for? What is the mechanism?
Used to treat patients with airway obstruction such as that produced by postoperative stridor.
Mixture’s lower density compared to oxygen alone, which increases the flow of gas across obstructed airways.
How to treat stridor
- supplemental or humidified oxygen therapy
- inspired racemic epinephrine
- steroids
- noninvasive positive-pressure ventilation modalities
- helium-oxygen combinations
- Intubation (last resort)
What is Renauds number proportional to?
Re is directly proportional to gas density (ρ), gas velocity (v), and diameter (D)
indirectly proportional to gas viscosity (μ).
Most common cardiac manifestation of Rheumatoid artheritis
Mitral regurgitation is the most common
Aortic valve disease, especially aortic regurgitation, is also often seen. Stenotic valve lesions are not typically associated with RA.
Electrolyte abnormality associated with hyperventilation (respiratory alkalosis)?
Hypocalcemia.
In response to alkalosis, hydrogen ions bound to negatively charged plasma proteins, such as albumin, are released. Calcium, being positively charged, can then bind to albumin and other proteins, thereby decreasing the serum calcium concentration (particularly the free/ionized, active fraction). This is the mechanism behind paresthesias that occur with hyperventilation.
Hypokalemia.
Hydrogen-potassium transporters pump hydrogen ions out of cells in the setting of alkalosis to restore physiologic pH. Simultaneously, potassium is pumped intracellularly to ensure electroneutrality.
Alkalosis can cause hypophosphatemia.
A rising cellular pH stimulates the glycolytic pathway, enhancing sugar-phosphate production. This triggers increased cellular uptake of phosphorus, thus decreasing serum phosphorus concentration.
Management of Von Willebrand disease in pregnant women undergoing c-section. Which clotting factor is deficient?
Indication for treatment?
von Willebrand factor serves as a carrier protein for factor VIII
von Willebrand disease (vWD) who have a factor VIII level >50% do not require treatment during labor or cesarean delivery. During pregnancy, there is an increase in the levels of factor VIII and von Willebrand factor (vWF) that normally corrects the deficiency seen in type 1.
Desmopressin when factor VIII levels are < 50%
If pt doesnt respond, Humate-P or Alphanate can be used, which is a concentrate of factor VIII and vWF.
If actor VIII is < 50%, desmopressin should be administered for type 1, and factor VIII and vWF concentrates should be administered for types 2 and 3.
IgA deficiency requiring transfusion, which type of transfusion is appropriate to minimize risk of anaphylaxis
Washed.
preparation involves washing the RBCs to remove donor plasma until IgA levels are reduced < 0.05 mg/dL
Mechanism of hypoxic pulmonary vasoconstriction (HPV) during OLV
Affect of NO and volatile anesthetics on hypoxic pulmonary vasoconstriction during OLV
Inhibits HPV
Presentation of congenital diaphragmatic hernia, initial management
In addition to nonspecific features of neonatal respiratory failure including retractions, grunting, nasal flaring, and tachypnea, CDH may present with a barrel-shaped chest, a scaphoid or sunken abdomen, unilateral breath sounds, and displacement of the heartbeat due to visceral displacement and mediastinal shift.
ETT, deliver low tidal volumes, low peak inspiratory pressures, permissive hypercapnia, and minimal supplemental oxygen to avoid further injury to the hypoplastic lung.
(PPV with mask/t piece is contraindicated due to risk of risk of forcing air into the stomach or loops of herniated bowel within the thorax.
unlateral cleft lip nerve block
Infraorbital nerve
How do inhaled anesthetics prolong muscle relaxant effects (3 ways)
- augmentation of the antagonist’s affinity at the receptor site
- central effects on alpha motor neurons and interneuronal synapses,
- nhibition of postsynaptic nicotinic acetylcholine receptors.
Which drug used to treat hypotension in critical aortic stenosis?
Phenylephrine
In severe aortic stenosis, cardiac output is relatively fixed. The heart cant compensate for any vasodialation (decreased SVR). Coronary perfusion suffers bc decreased diastolic pressure.
Goal is to maintain normal to slower HR
Hypertrophic heart is at risk for ischemic changes even if no CAD (increased oxygen demand due to hypertrophied left ventricle). Atrial kick also contributes a lot to maintain the end diastolic volume.
Normal AV area
Severe aortic stenosis is defined as
Transvalvular pressure gradients higher than 40 mm Hg and a valve area less than 1 cm2 are characteristic of severe aortic stenosis.
What is Dalton’s law
Boyle’s law
the pressure of a gas is inversely proportional to its volume at a constant temperature
P1V2 = P2V2
P
Placenta delivery time in absence of hemorrhage
(In presence of hemorrhage?)
60 minutes
Postpartum hemorrhage usually results from: uterine atony, retained placenta, genital tract trauma, or coagulation disorders. Retained placenta is the second most common cause of PPH
placenta that has not been expelled within 30 minutes after delivery of a baby. The guidelines recommend, in the absence of hemorrhage, waiting an additional 30 minutes after diagnosis to allow for spontaneous expulsion. If this does not occur, controlled cord traction may be the first step in helping to expel the placenta. The addition of oxytocin may be beneficial, especially if the uterus is atonic, because uterine atony may result in failed separation/expulsion. Ergot alkaloids (e.g., methylergonovine) are not recommended, as they may cause tetanic uterine contractions, which can delay placental expulsion and make manual extraction more difficult. Additionally, prostaglandin E2 is not recommended, because it is associated with an increase in cardiac events.
which pediatric neurologic disorders would volatile anesthetics produce an increased pharmacodynamic effect?
Cerebral Palsy (CP) – more sensitive to the effects of volatile anesthetics, and a lower minimum alveolar concentration (MAC) may be required to achieve surgical anesthesia
Mechanism behind tachycardia and palpitations in untreated Graves’ disease
Hyperthyroidism is associated with upregulated expression of beta1-adrenergic receptors on cardiomyocytes, which increases cardiac sympathetic sensitivity with an increase in heart rate.
upregulation of sodium-potassium pump expression associated with hyperthyroidism drives a significant increase in the basal metabolic rate, producing classic clinical symptoms such as unintended weight loss and heat intolerance.
Test commonly used for high dose heparin administration and evaluates the intrinsic and final common pathways of the coagulation system?
activated clotting time (ACT) is commonly used to evaluate the anticoagulant effect of high dose heparin administration
Whole blood is added to a tube that contains an activator substance (celite or kaoline) and time to clot formation is measured.
normal ACT is around 107 seconds.
A value between 400-480 seconds is typically required to initiate cardiopulmonary bypass.
Hypothermia, hemodilution, thrombocytopenia (< 30-50,000/uL), and platelet inhibitors also prolong the ACT.
Decreased maximum amplitude (MA) primarily provides evidence of
thrombocytopenia and/or platelet dysfunction
Which are the most resistant evoked potentials to the effects of volatile anesthetics?
Brainstem auditory evoked potentials (BAEPs)
hearing sounds, such as talking, music, or conversations, is one of the most commonly reported experiences for patients with intraoperative awareness.
Nerve that supplies sensory innervation to the laryngeal mucosa ABOVE the vocal cords?
Internal branch of the superior laryngeal nerve provides sensory innervation to the laryngeal mucosa superior to the vocal cords.
What does the External branch of the superior laryngeal nerve innervates? Internal branch?
External branch of the superior laryngeal nerve provides MOTOR innervation to the cricothyroid muscle.
Internal - sensory above the vocal cords
recurrent laryngeal nerve provides ?
recurrent laryngeal nerve provides sensory innervation to laryngeal tissue below the vocal cords.
Activated clotting time (ACT) is used to monitor
Activated clotting time (ACT) is used to monitor the effect of high-dose UFH therapy in situations where aPTT is not clinically useful or takes too long (e.g. cardiopulmonary bypass).
molecular mechanism by which inhaled beta-agonist agents lead to bronchodilation? cAMP vs cGMP
cAMP
Beta-2-adrenergic receptor activation causes bronchodilation mediated by the intracellular second messenger cyclic adenosine monophosphate (cAMP).
MOA of Atropine
anticholinergic that indirectly increases the heart rate by blocking parasympathetic innervation to the heart.
anti-hypertensive medication that can cause direct cerebral vasodilation
Nicardipine.
cerebral autoregulation occur at MAP values of approximately 60 and 160 mmHg
Calcium channel blockers, nitroglycerin, hydralazine, nitroprusside, and adenosine also cause direct cerebral vasodilation and may decrease cerebral vascular resistance to a greater extent, increasing CBF higher than what would be expected by the autoregulation mechanism alone.
Propofol infusion syndrome (PRIS) signs and symptoms… treatment?
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. Stop prop and supportive tx.
bicuspid aortic valve, patent ductus arteriosus, and epistaxis associated with
Coarctation of the aorta
nitric oxide causes smooth muscle relaxation via which pathway (cAMP vs cGMP)?
cGMP
intracellular cyclic GMP has been associated with inhibited leukocyte adhesion, platelet activation, as well as leukocyte proliferation.
Pt with COPD may develop acutely worsened hypercapnia with the administration of supplemental oxygen because of
increase in ventilation/perfusion (V/Q) mismatch
(not because of central respiratory drive)
Hypoxic pulmonary vasoconstriction (HPV) redistributes pulmonary blood flow to areas of the lung with higher alveolar oxygenation content. O2 inhibits HPV, allowing blood (perfusion) to those alveoli with retained CO2… this high concentration of CO2 in alveoli prevents CO2 in blood to be exchanged.
Meperidine works on the _____ opiod receptor
when do we use meperidine?
Kappa
Used as antishivering
causes accumilation of proconvulsant metabolites in renal falure patients
U1 receptor produces
analgesic and physical dependence properties of most opioids
U2 receptors results in
respiratory depression, miosis, euphoria, decreased gastrointestinal motility, and physical dependence.
What symptoms are most characteristic of myofascial pain syndrome?
Palpable taut bands with radiating pain
arising from a trigger point, the trigger point is felt as a palpable taut band.
management of myofascial pain syndrome?
repeated applications of a cold spray over the trigger point in line with the involved muscle fibers, followed by a gentle massage of the trigger point and stretching of the affected muscle. Another treatment is local anesthetic injection or dry needling of the trigger point.
Ketamine EEG patern
Active EEG patern: fast oscillations in the high beta range to low gamma range.
Ketamine affect on cerebral metabolic rate of oxygen and cerebral blood flow.
increased CMRO and CBF
Dexmedetomidine MOA
presynaptic α2 adrenergic receptors, hyperpolarizing neurons located in the locus coeruleus, and decreasing norepinephrine release from neurons projecting from the locus coeruleus to the preoptic area of the hypothalamus
Dexmedetomidine MOA similar to what type of sleep patten, why?
nonrapid eye movement (NREM) sleep
EEG pattern observed during stage II nonrapid eye movement sleep
formula for standard error
SE = Standard deviation / sqrt (sample size)
SE = SD / sqrt (n)
Vasopressin MOA
WHich patients to avoid in …
V1 receptor = increase SVR
V2 = increase water reuptake via aquaporin channels = increase bllood volume
Avoid in coronary artery disease, administration of vasopressin can cause myocardial ischemia due to the vasoconstriction of stenotic areas thus caution must be taken in this patient population.
vasopressin safe in renal dysfunction and liver failure.
Vasopressin increased ciculating vWf andf FVIII
DDAVP - doesnt cause systemic htn
coronary artery MOST LIKELY to be implicated in acute onset bradycardia
Right Coronary Artery can affect the conduction system, which can lead to significant hemodynamic alterations and bradyarrhythmias.
Cause for unilateral block after epidural
epidural catheter that is located laterally in the epidural space,
inadequate local anesthetic
the presence of the plica mediana dorsalis (midline fold on the dura mater that extends to the ligamentum flavum)
at what point in cerebral blood flow does irreversible brain damage begin to occur
Irreversible brain damage is seen at flow of 6-12 mL/100 g/min.
Ischemia begins at 20 mL/100 g/min.
Average CBF in the normal brain is 50 mL/100 g/min
Donepezil causes ________relaxation after succinylcholine and show ___________ resistance to nondepolarizing muscle relaxants. Mechanism?
Donepezil is a reversible, non-competitive inhibitor of acetylcholinesterase which can cause increased availability of acetylcholine at neuromuscular junctions.
increased presence of acetylcholine, patients on donepezil will have prolonged relaxation after succinylcholine and show increased resistance to nondepolarizing muscle relaxants. Some sources recommend that donepezil be held 2-3 weeks prior to surgery.
congenital diaphragmatic hernia vent manamgement
Gentle ventilation” with permissive hypercapnia using a low tidal volume strategy, PIP < 25 cm H20, and FiO2 + PEEP adjustment to maintain preductal SpO2 of 90-95%
spine block with highest chance for intravascular injection
Cervical spine facet injections carry a higher risk of intravascular complications. This is due to the vertebral artery lying just lateral to the cervical facet joint.
Anesthetic considerations for cushings syndrome patients
blood pressure regulation (these patients are typically hypertensive)
glucose control,
balancing electrolytes (often hypokalemia),
and positioning (due to osteopenia).
Indications for Retrograde cardioplegia over Anterograde cardioplegia
diffuse obstructive coronary artery disease (CAD) aortic insufficiency (AI), surgeries involving significant manipulation of the aortic root or coronary ostia.
How is antegrade cardioplagia administered?
via a small-bore catheter or needle in an antegrade fashion at the aortic root or directly into the coronary arteries.
Why is duplicated or persistant left-sided SVC contraindicated for retrograde cardioplagia?
duplicated SVC, which is thought to arise from a failure of the left anterior cardinal vein to involute during embryologic development, typically serves the same function as the left brachiocephalic vein but empties into an enlarged coronary sinus rather than the right atrium.
Retrograde infusion into the coronary sinus in a patient with a duplicated SVC would potentially result in systemic (rather than solely myocardial) distribution of cardioplegia solution.
Treatment for vasospastic angina (transient episodes, nausea, occur at rest)
Calcium Channel Blockers (nicardipine)
(nitrates are second line - produce tolerance with repated use)
How to prevent febrile blood transfusion reaction
Leukoreduction involves the reduction of white blood cells (WBC) from the red blood cells (RBC) to be transfused.
Leukoreduction reduces risk of HLA alloimmunization, febrile reaction, and CMV transmission.
IL-1 released during storage stimulates prostaglandin E2 causing fever.
Blood Irradiation with 2.500 cGY pevent what reaction?
Irradiation with 2,500 cGY damages the WBC DNA which prevents a proliferative response to the recipient’s tissues. It is used to prevent graft versus host disease especially in those who are immunosuppressed.
What type of blood is used for IgA deficiency?
Washed
Washing with saline is performed for blood to be used in patients with a history of allergic transfusion reactions such as IgA deficiency.
Noonan syndrome
Causes of citrate toxicity
Metabolic alkalosis
Hypocalcemia
Hyperventilation (alkalosis)
Function of citrate
Citrate used as an anticoagulant becuase it chelates ionized calcum
Calcium initiated clotting (thus inhibition of calcium in stored blood products through citrate chelation helps prevent clotting of the stored cells.)
