Clinical Anesthetics Flashcards
goals of general anesthesia
analgesia, amnesia, unconsciousness, suppression of responses to surgery (stress, motor, CV, pain)
drugs for analgesia
isoflurane, morphine
drugs for amnesia
midazolam, isoflurane
drugs for unconsciousness
propofol, isoflurane
drugs for suppression of responses
cis-atracurium muscle relaxant (neostigmine + glycopyrrolate), fentanyl, isoflurane, phenytoin (seizures), dexamethasone, hydralazine, labetalol, ondansetron, morphine
rationale for using multiple drugs
maximize benefit, minimize problems (use IV and inhaled together)
example of a drug that could have been used for amnesia, analgesia, unconsciousness, muscle relaxation; why it isn’t used?
sevoflurane
slow induction, severe CV depression, cerebral vasodilation, prolonged emergence, inadequate post op pain control
what about drug interactions?
reduced doses minimize side effects, and balanced anesthesia techniques rely on interactions
explain how the effects of drug interactions are “additive”
effect of drug combo is expected based on SUM of doses; 1/2 ED + 1/2 ED= 1 ED
explain how the effects of drug interactions are “synergistic”
effect of 1 drug is enhanced by another, so the combined effect is greater than expected based on the sum of the doses; 1/2 ED + 1/2 ED > 1 ED
examples of beneficial drug interactions
benzodiazepines/opioids; midazolam/propofol for preop sedation/induction; combos of inhaled agents; inhaled agent and muscle relaxant; labetalol/hydralazine; treatment of N/V
pharmacokinetic interaction of midazolam and fentanyl
competitive inhibition of CYP3A4 by fentanyl, altering midazolam clearance at high doses
describe the 2nd gas effect
uptake of 1st gas reduces lung volume, increases conc of 2nd gas/ increases uptake of 2nd gas
using an inhaled agent with NMBD (neuromuscular blocking drug) allows…
lower dose of NMBD antagonists
all NMBDs increase blockade by..
decreased prejunctional ACh release
decreased postjunctional sensitivity to ACh
