anesthetics Flashcards
5 general benefits/uses of anesthesia drugs?
Sedation and reduced anxiety Lack of awareness and amnesia Skeletal muscle relaxation Suppression of undesirable reflexes Analgesia
can one drug do all five benefits/uses of anesthesia drugs?
NO, generally combine IV and inhaled to maximize effects and avoid ADRs
which is cheaper and easier to use? IV or inhaled anesthetics?
IV
what do IV anesthetics do? what are they used for? (used alone, vs adjunct, vs continual infusions)
rapid induction of anesthetic effect
- alone: short procedures, anesthesia
- continual infusions: longer procedures
- adjuncts: to inhaled
what is the one IV barbituate anesthetic agent?
methohexital (brevital)
what is the MOA of methohexital (brevital)?
binds barbiatuate site on GABAa receptor
–> enhance Cl- channel opening to increase GABA inhibitory effect on the receptor.
how long does it take methohexital (brevital) to work?
fast, 30 sec. rapid induction of sleep
2 ADRs of methohexital?
- respiratory depression
2. hypotension (from VasoDilation)
what is the MOA of IV propofol and IV Etomidate, ?
binds beta subunit on GABAa receptor
–> enhance GABA inhibitory effect
what is the major benefit of IV propofol over IV methohexital ?
kinetics: rapid on, rapid off receptor.
- Recovery is better- less N/V
what are the kinetics of IV propofol?
rapid!
onset- 30sec, rapid metabolism, short 1/2 life (30-60min)
3 ADRs of IV propofol? (maybe weeds)
Apnea, decrease cardiac output, hypotension
drug of choice for shorter ambulatory procedures in the OR? what is used prior to admin of other anesthesias?
short in OR: IV propofol
prior: IV ketamine
when would you choose to use IV etomidate? (over propofol)
if BP low before surgery – agent has minimal cardiac and respiratory depression
only Side Effects:
Nausea/vomiting on emergence from anesthesia
what is the 2 part MOA of IV ketamine?
- blocks NMDA glutamate (excitatory) receptor in CNS = rapid hypnotic state
- mu opiod agonist - analgesic effects
which IV drug Produces rapid hypnotic state (dissociative anesthesia) where patient exhibit analgesia, are unresponsive to commands, have amnesia, their eyes may open and limbs move involuntarily?
IV ketamine
what are the two major advantages of IV ketamine over other anesthetics?
1 . No risk for hypotension or bronchospasm
(increases HR, BP & cardiac output)
2. Pediatric procedures: @ low doses in combo with others (propofol &/or midazolam)
what would you use for a short painful procedure on a kid (like burn dressing change)?
IV ketamine
ADRs of IV ketamine?
illusions
increases HR, BP and CO
major MOA of inhaled anesthetics?
bind beta subunit on GABAa (inhibitory) receptor
same as IV propofol and Etomidate
what are the 3 other MOAs of inhaled anesthetics? what do they all lead to?
- inhibit NMDA receptors
- activates K+ channels
- inhibits nicotinic (excitatory) receptor- activated cation channels
- -> hyperpolarization and reduced membrane excitability
onset and duration of inhaled anesthetics? (maybe weeds)
onset: 2-3min
duration: <2hrs
5 ADRs of inhaled anesthetics?
shivering blurry vision weak for a few days following after administration *Rare: hepatotox *Rare: malignant hyperthermia
two types of inhaled anesthetics
- inhaled gas - nitrous oxide
2. volatile agents (liquid turns to gas)- “-fluranes”
what was “tweaked” to create the volatile inhaled agents “-fluranes”? why? (weeds)
Halothane - tweaked b/c ADRs were bad
what are the local anesthetics?
“-aine” s
*cocaine was the original
MOA of local anesthetics? (“-aine”s)
reversible inhibition: bind Na+ channel, decrease nerve membrane permeability to Na+
- -> axn potential can’t propegate
- -> sensory input lost (pain and temp)
what happens with repeated injections of local anesthetics? (“-aine”s)?
tachyphylaxis: loses effectiveness
what are the 2 groups that the local anesthetics are broken into?
esters and amides
which drugs are in the ester local anesthetic group?
COCAINE
PROcaine
chloroPROcaine
TETRAcaine
which drugs are in the amide local anesthetic group?
Prilocaine
Lidocaine
“-vacaine”s
which are the longest acting local anesthetics?
bupi-vacaine, ropi-vacaine
("V caine is VERY long lasting ")
and
Tetracaine
(think "4 times as fast")which are the shortest acting local anesthetics?
Procaine and chloroprocaine
“ PROs need to recover QUICK”
what is the most important factor for determining DOA and potential for Tox with local anesthetics?
local blood flow:
anesthetic cause vasodilation= rapid drug abs and systemic abs. = increased toxicity
how can you avoid the short DOA and toxicity risk with local anesthetic? (weeds)
give epi with it
Epi vasoconstricts = longer DOA, less systemic abs and less toxicity
local anesthetic effect in injured tissue ?
injured tissue = inflammation and acidosis
–> lower pH = ionization of local anesthetics
(need to be NON-ionized in order to get into cell and have effect)
OVERALL: doesn’t work as well
where can you NOT use local anesthetic w/ epi ?
where vasoconstriction could result in permanent tissue destruction
Nose, ear, penis, or ends of digits (fingers and toes), peripheral vascular disease
what are the two systemic toxicity complications that come from abs. of too much local anesthetics ?
CNS/neuro
Cardiovascular
CNS/neuro tox from too much local anesthetic abs?
numb tongue + metallic taste
nystagmus + muscle twitch
seizure + CNS depression
cardiovascular tox from too much local anesthetic abs?
bradycardia, severe hypotension, cardiac arrest
what is the one exception from usual cardiovasc. tox progression from too much local anesthetic abs?
cocaine: vasoconstriction, HTN, & ventricular arrhythmia
Vasoconstriction= ischemia (why you see ulceration of membranes & damage to septum occur when abused nasally)
what drug combo is used to make cream to numb area: apply before venipunture (for putting in port for chemo) ? (weeds)
prilocaine/lidocaine (EMLA) cream
what drug is used to make lozanges/gels for teeth pain? (weeds)
benzocaine
what drug is this…
IV/IM drug of choice for preoperative sedation, anxiety and amnesia
Causes high amnesia – often given before entering OR
a benzodiazepine (Midazolam aka Versed) injectable
when are opiods used with anesthetics?
low dose opioids: premedication & adjunct
…as adjunct: decrease pain so don’t need as high a dose to achieve anesthesia
* In high risk surgery to minimize CV depression
what two anticholinergics are used with anesthetics? why?
atropine and glycopyrolate
- restore cardiac rate (prevent reflex brady) and BP during anesthesia
(stimulates M2)
anesthesia adjunct: to relieve anxiety
benzodiazepine
anesthesia adjunct: to prevent gastric acid secretions
H2 blockers
anesthesia adjunct: prevent allergic rxns
antihistamines
anesthesia adjunct: prevent aspiration of gastric acid secretions, post-op N/V
antiemetics
anesthesia adjunct: to provide analgesia
opioids
anesthesia adjunct: to prevent bradycardia + secretion of fluids into respiratory tract
anticholinergics
anesthesia adjunct: to facilitate intubation + relaxation
neuromuscular blocking agents
