Exam 2- PNS Flashcards
what can affect contact with the PNS?
diaphoresis, hair, edema, wounds
what nerve innervates the adductor pollicis muscle?
the ulnar nerve
what is nerve stimulation of the adductor pollicis muscle a good indication of?
recovery of upper airway muscle function
which muscle used for PNS recovers later than the diaphragm?
the adductor pollicis muscle
where are adductor pollicis nerve stimulator monitors placed?
electrodes are placed over the path of the ulnar nerve
black is distal at the level of the wrist on the ulnar surface
red is placed 1-2 cm proximal, parallel to the flexor capri ulnaris tendon
what muscles are stimulated during facial nerve stimulation?
orbicularis oculi- covers the eyelid, produces eyelid squint
corrugator supercilii- covers the eyebrow
which location of stimulation is a good predictor of good intubating conditions and profound block?
eyebrow stimulation
where are electrodes placed for facial nerve stimulation
red wire is proximal at the outer canthus
black wire is distal at the tragus
diaphragm paralysis vs adductor pollicis
diaphragm and laryngeal muscles take x2 the dose to paralyze compared to the adductor pollicis muscle
face is not a good indicator of
extubation
which nerves are paralyzed faster and recover quicker?
facial nerves
posterior tibial nerve stimulation produces
plantar flexion of the big toe, comparable to adductor pollicis
where are the electrodes placed in posterior tibial nerve stimulation?
2 cm posterior to the medial malleolus, second one is 2 cm above the first
0.1 Hz
one stimuli every 10 seconds
what Hz causes sustained muscle contraction/tetanus without fade?
50 Hz
what can repeated simulation cause?
fatigue and increased blood flow to the area
which method of PNS is the least reliable method?
single twitch
what is single twitch PNS used for
to determine the onset of a block; NOT RECOVERY
train of four (TOF) stimuli
4 repetitive stimuli at 2 Hz (2/sec)
what PNS is associated with fade in NDMR?
train of four (TOF)
what is the minimum standard for determining extubation readiness?
TOFr/= 0.9
fade ratio
relationship between the size of the fourth twitch and the first twitch (T4/T1)
no muscle relaxant TOF ratio
1.0
full muscle relaxant ratio
0
which PNS method can detect a phase II block?
TOF
100% blocked TOF
no response, flaccid, no TOF
95% blocked TOF
no twitches, but the diaphragm may move
90% blocked TOF
1 twitch on TOF, adequate relaxation of abdominal muscles
70-75% blocked TOF
4 twitches on TOF, VC and TV can be normal
30% blocked TOF
head lift/hand grasp sustained
which kind of block would demonstrate fade?
a nondepolarizing block
how would a depolarizing block appear during phase I?
constant but diminished
how would a depolarising block appear during phase II?
fade, TOF <0.3
what TOF indicates adequate surgical relaxation?
0.15-0.25
what TOF indicates safe extubation and recovery
> 0.9
describe tetanic (TET) stimulation
repetitive stimulation at a frequency >30 Hz
5s durations
fades when partially blocked
which kind of stimulation is an indicator of residual NMB
TET stimulation
which kind of stimulation fades when partially blocked
TET
what kind of stimulation is used with sugammadex reversal?
post tetanic count (PTC)
post tetanic count stimulus
5 second, 50 Hz tetanic stimulus, followed 3s. later by a single twitch stimuli at 1 Hz
double-burst stimulation
two short bursts of tetanus at 50 Hz
each burst has 3 impulses lasting 0.2ms
which stimulator has a greater magnitude of muscle response than TOF
double-burst stimulation
nondepolarizing neuromuscular block
no twitch
depolarizing block
phase I and phase II
phase I is preceded by muscle fasciculation
which block has no fade?
depolarizing block (succinylcholine)
which block does have fade?
nondepolarizing block
which PNS site should be used during anesthesia induction
orbicularis oculi as it is more similar to a central muscle
what simulation pattern should be used during induction?
single twitch or TOF
what muscle is the best option for PNS monitoring during reversal and recovery?
adductor pollicis stimulation
which method is BEST for PNS?
acceleromyography (AMG) because it provides a ratio
