Muscle Relaxants Flashcards
Muscle Relaxants - Ultra Short Acting
succinylcholine
5-15 minutes
Muscle Relaxants - Short Acting
mivacurium
20-40 minutes
Muscle Relaxants - Intermediate Acting
atracurium
cisatracurium
vecuronium
rocuronium
30-60 minutes
Muscle Relaxants - Long Acting
pancuronium
60-90 minutes
Muscle Relaxants - onset time
time from administration to maximal effect
Muscle Relaxants - clinical duration
time from administration to 25% recovery of the twitch response
Muscle Relaxants - total duration of action
time from administration to 90% recovery of the twitch response
Muscle Relaxants - recovery index
time from 25% to 75% recovery of twitch response
Train of 4 Ratio
compares the 4th twitch with the 1st twitch; recovery is indicated with the ratio is 90%
neuromuscular blockage tests that reflect diaphragm paralysis
orbicularis oculi of facial nerve
upper airway muscle are more sensitive than peripheral muscles
neuromuscular blockage - best site to measure recovery
ulnar nerve
neuromuscular blockage - best site to measure onset
facial nerve - orbicularis oculi or corrugator supercilii*
sequence of loss of muscle function
- eye lids
- extremities
- chest - intercostals
- abdominal muscles
- diaphragm
blockade responses
4 responses, no fade = <70% 4 responses, fade = 70-75% 3 responses = 75-80% 2 responses = 80-85% 1 response = 90-95% **want surgery here 0 responses = 100%
twitches with depolarizing drug
no fade or post-tetanic count
sustained response to tetany
muscle fasciculation
Post Tetanic Count
- 50 Nz for 5 seconds
- Wait 3 seconds
- Single twitches every second for up to 20 seconds
number of twitches inversely proportional with recovery time, 1 twitch 15-30 minutes
TOF ratio when fade is no longer detected, which leads to
0.4-0.9
“blind paralysis”
Esterase Enzymes
cholinesterase: acetyl and pseudo (plasma)
non-specific: RBC, paraoxonase, albumin
metabolism - succinylcholine
pseudocholinesterase
metabolism - mivacurium
pseudocholinesterase
metabolism - atracurium
Hoffman elimination and non-specific esterase
elimination - 10-40% renal
metabolism - cisatracurium
Hoffman elimination and non-specific esterase
elimination - 15% renal
test for determining cholinesterase variants
dibucaine - inhibits typical but not atypical and measure activity
low number - indicates atypical enzymes
low activity - indicates low levels of enzyme
succinylcholine side effects
hyperkalemia dysrhythmias: tachycardia, bradycardia in repeat doses myalgia elevated intragastric pressure elevated ICP elevated intraocular pressure myoglobinemia massester spasm malignant hyperthermia
atracurium
cisatracurium
mivacurium
benzylisoquinoline relaxants
pancuronium
vecuronium
rocuronium
steroidal relaxants
metabolism - vecuronium
liver (40%) - removed by kidneys and liver
metabolism - rocuronium
not metabolized - removed by liver (70%) and kidney (25%)
metabolism - pancuronium
liver (20%) - removed by kidneys (85%)
which relaxant releases histamine
atracurium > mivacurium
small amount released with succinylcholine
factors prolonging paralysis
hypothermia aminoglycoside toxicity penicillin toxicity steroid myopathy clindamycin tetracycline volatile anesthetics dantrolene magnesium lithium
intubating dose - succinylcholine
1-1.5 mg/kg
intubating dose - mivacurium
0.2 mg/kg
intubating dose - atracurium
0.5 mg/kg
intubating dose - cisatracurium
0.1 mg/kg
intubating dose - rocuronium
0.6-1 mg/kg
intubating dose - vecuronium
0.1 mg/kg
intubating dose - pancuronium
0.08-0.18 mg/kg
time to onset - succinylcholine
30-60 sec
time to onset - mivacurium
3 min
time to onset - atracurium
2-4 min
time to onset - cisatracurium
2-4 min
time to onset - rocuronium
1-1.5 min
time to onset - vecuronium
2-4 min
time to onset - pancuronium
2-4 min
sugammadex reversal doses
2 mg/kg if >2 twitches
4 mg/kg if 1 twitch
16 mg/kg after intubation dose
dose - neostigmine
0.03-0.07 mg/kg
dose - edrophonium
0.5-1 mg/kg
dose - atropine
0.01 mg/kg
dose - glycopyrrolate
0.01 mg/kg
max dose - neostigmine
5 mg
max dose - edrophonium
1 mg/kg
time to onset - neostigmine
7-10 min
time to onset - edrophonium
5-10 min
time to onset - atropine
1-1.5 min
time to onset - glycopyrrolate
2 min
time to onset - sugammadex
1-1.5 min
duration - neostigmine
55-75 min
duration - edrophonium
15-60 min
duration - atropine
15-30 min
duration - glycopyrrolate
1-2 hours
why does fade occur?
the presynaptic receptors are being blocked
sugammadex adverse drug reactions
dry mouth dysgeusia n/v coughing hypotension abnormal levels of N-acetylglucosaminidase in urine chills inactivate birth control
relaxants - response when 80% of receptors are occupied
tidal volume of 5 ml/kg
single twitch is as strong as baseline
relaxants - response when 70% of receptors are occupied
TOF and sustained tetanus for 5 seconds - no fade
vital capacity of 20 ml/kg
relaxants - response when 60% of receptors are occupied
double burst no fade
relaxants - response when 50% of receptors are occupied
hand grip head lift sustained bite sustained tetanus @ 100 htz inspiratory force at least -40 cm H2O
characteristics of neuromuscular blockade - phase 1 vs phase 2
- phase 1 = depolarizing
- phase 2 = non-depolarizing
anti-cholinesterase drugs ______ phase 1 drugs and _____ phase 2 drugs
- potentiate
- reverse
medications that inhibit cholinesterase
donepezil rivastigmine galantamine tacrine physostigmine phospholine iodide (anticholinesterase eye drops)
