Stanford Anesthesia Pimp Questions – Flashcards
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how do most IV anesthetics exert effects? and exceptions?
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sedation and hypnosis thru GABA receptors (primary CNS inhibitory NT)- increase Cl- conductance thus hyper polarization (promotion of inhibition) ketamine: NMDA receptor blocker and dexmedetomidine: central a-2 blocker
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how do propofol and barbiturates increase GABA effect?
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decrease rate of dissociation of GABA and its receptor
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how do benzos effect GABA?
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increase efficiency of GABA receptor and Cl- channel coupling
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between midazolam (versed), diazepam (valium), and lorazepam (ativan), which is longest duration of action?
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lorazepam (ativan)
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propofol is in what type of emulsion?
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egg lecithin/yolk (important distinction because most egg allergies are egg whites)
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induction dose of propofol
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1.5-2.5 mg/kg children- more, larger Vd and higher clearance elderly-less
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infusion dose of propofol
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hypnosis: 100-200 mcg/kg/min sedation: 25-75 mcc/kg/min
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induction dose of etomidate
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0.2-0.3 mg/kg
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common on injection of etomidate
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pain, maybe myoclonus
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great thing about etomidate
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maintains cerebral perfusion pressure (CPP) because less decrease in SBP and maintains hemodynamic stability (no His release)
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bad things about etomidate
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increased PONV inhibits adrenocortical synthetic function (5-8 hours)
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thiopental precipitates in acidic solutions so DO NOT MIX with
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LR or Roc
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dont inject thiopental where?
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intra arterial (vasoconstriction, thrombosis, necrosis) tx with papaverine (opium alkaloid antispasmodic drug) and lidocaine and heparinization
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ketamine produces what kind of state
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dissociative (analgesia and amnesia while maintaining consciousness)
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high incidence of what with ketamine
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psychomimetic rxns (attenuated with co-admin with midazolam)
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where is ketamine contraindicated
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neurosurgery (increases CMRO2, CBF, ICP)
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all benzos have what properties?
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sedative, amnestic, hypnotic, anxiolytic (not analgesic)
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premedication dose of versed vs induction dose
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premed: 1-2 mg (0.04-0.08 mcg/kg) induction: 2.5 x premed dose (0.1-0.2 mg/kg)
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reversing benzo
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flumazenil 45-90 mins of action after 1-3 mg dose (benzo is eliminated more slowly compared to effect of flumazenil so may see re-sedation)
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MOA of dexmedetomidine
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central a2 blocker hypnotic and analgesic
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perk of dexmedetomidine
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opioid sparing so non significant depression of respiratory drive
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pharmacology of opioids
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mu opioid receptor agonism periaqueductal gray matter and substantia gelatinosa of cord reduces MAC of volatiles
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morphine pharmacology
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slow peak time (80% by 15 mins, peak effect 90 mins) active metabolite, morphine 6 glucuronide is renally excreted and can cause His release
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hydromorphone pharmacology
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rapid onset (peak in 15 mins) 8x potent no metabolite, no His
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fentanyl pharmacology
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fast and short (5 mins, t1/2 30 mins) 100x potent
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sufentanil pharmacology
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fast but slower than fentanyl 10x fentanyl more rapid recovery
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alfentanil pharmacology
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fastest onset (90 secs) because crosses BBB more quickly more NV, chest rigidity, and resp depression brief duration due to rapid redistribution
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remifentatil pharmacology
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peak effect 90 secs uniquely metabolized by plasma esterases
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meperidine pharmacology
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peak 15 mins, lasts 2-4 hrs normeperidine lowers seizure threshold and really excreted tx shivers anti-ach effects: tachycardia avoid with MAOIs (CNS depression or excitation) His release euphoric effect with less respiratory depression
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strategy for brief intense stimulation
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retrobulbar block, mayfield head pins, rigid bronch remifentanil or alfentanil
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cardiac equations
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CO = SV x HR SV = EDV - ESV so CO = (EDV-ESV) x HR BP = CO x SVR so CO = BP/SVR
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what is the dicrotic notch
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notch in invasive arterial pressure curve representing aortic valve closure, producing brief retrograde flow
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what is MAP
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2DBP+SBP/3
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normal PP, high low
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normal is 40mmHg narrow (40)- AR, atherosclerosis, PDA, high output state
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odd drugs that cause hypotension
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protamine, vancomycin
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surgical events that cause hypotension
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pneumoperitoneum, obstructed venous return, vagal reflexes
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vent changes that can help hypotension
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decrease PEEP decrease I:E
