NMG, Reversal Agents, Antimuscarinic Flashcards
What are the mechanisms of action of NMBs?
- depolarizing muscle relaxants act as ACh receptor agonists then antagonists
- nondepolarizing muscle relaxants function as competitive antagonists
What are the 4 non-depolarizing, competitive muscle relaxants?
Pancuronium
Vecuronium
Atracurium
Rocuronium
What is phase I block of sux?
Depolarizing phase
What is phase II of Sux?
Desensitizing phase
-block converts from depolarizing to nondepolarizing block (occur with larger doses or prolonged infusion
What is surmountable antagonist?
Produce parallel rightward shifts of agonist dose–response curves with no alteration of the maximal response (can be overcome)
Is Sux susceptible to acetylcholinesterase?
NO
What are the 4 things that impact Sux duration of action?
Hypothermia
Low enzyme
Genetic
Clinical pearl
How to manage hyperkalemia for Sux?
Insulin + glucose to prevent hypoglycemia
Calcium gluconate to stabilize cardiac rhythm
Reduce K level with dialysis
When to NOT use Sux?
Underlying NM disease Risk of MH History of allergy to sux Homozygous for atypical plasma cholinesterase High K concentration
Plasma cholinesterase metabolizes which ND agent?
Mivacurium
Nonezympatic metabolizes which NG agent?
Atracurium, cisatracurium
Hepatic metabolizes which NG agent?
Vecuronium
Rocuronium
Renal metabolizes which NG agent?
Pancuronium
Doxacurium
Which NG agent has an intermediate acting?
Atracurium
Rocuronium
Vecuronium
Which NG agent has long acting?
Pancuronium
Which NG agents cause histamine release?
Atracurium
Mivacurium
Which NG agent have a vagal blockade?
Rocuronium
Pancuronium
What does atracurium use for metabolite?
Laudanosine
Key things about cisatracurium (5)
Intermed onset and duration Does not affect histamine release Lacks HR and BP effects Laudanosine metabolite Sorted in refrigerator because loses potency at room temp
Key things about pancuronium (5)
Intermed onset and duration Metabolized by liver Elimination by kidney Stored in refrigerator, stable at room temp for 6months Hypertension and tachycardia
Key things about vecuronium (3)
Intermed onset and duration
Stable BP and HR
Neonates
Key things about rocuronium (4)
Faster (but longer than Sux) onset and intermed duration
No metabolism
Eliminated by liver and kidney
Less potent so requires bigger doses
Monitoring of NM block?
Peripheral nerve stimulator
When does single twitch stimulation completely disappear?
90-95% receptors occupied
Train of four monitoring
1st 90-98% block
2nd 85-90% block
3rd 80-85% block
4th 75% block
Recovery TOF ratio:
.9
How does cholinesterase inhibitors work?
Increase ACh activity by increasing duration of time present to act at receptors
What are the 3 types of AChE inhibitors?
Reversible 1 alcohol structure - edrophonium 2 carbamic acid esters (carbamates) - Neostigmine Irreversible 3 organophosphates
Mechanism for both AChE inhibitors?
Non depolarizing, competitive
Compete with Ach to bind with nicotinic receptor of motor end plate
Neostigmine onset and duration
5 - 10 min
1 hour
Pyridostigmine onset and duration
10-15min
>2hrs
Edrophonium onset and duration
1-2min
1hr or less
Mechanism of action for Sugammadex
Encapsulates or chelates the free molecule form of rocuronium (maybe vecuronium) to make soluble in plasma
Sugammadex metabolism and elimination
No metabolites and really eliminated
How long do you have to wait to redose Sugammadex with rocuronium and vecuronium?
24hrs
What kind of effect does anti muscarinic have on body?
Inhibit Parasympathetic nervous system
What is atropine onset and duration?
Faster onset
Shorter duration
What is glycopyrrolate onset and duration?
Slower onset
Longer duration
