Week 4- Peripheral Nerve Stimulators Flashcards
Things that can affect contact of peripheral nerve stimulators (name 5)
- diaphoresis
- hair
- edema
- wounds
- anything interfering with conduction
what nerve innervates the adductor pollicis muscle
ulnar nerve
when stimulating the adductor pollicis muscle, where/what response are you looking for
thumb adduction/twitching
stimulation of which peripheral nerve is a good indicator of recovery of upper airway muscle function
adductor pollicis muscle
the adductor pollicis is sensitive to NMBs and recovers later that what 3 muscles
- diaphragm
- laryngeal adductors
- abdominal muscles
The surgeon says to you “the patient is breathing, their diaphragm is moving.” but you have no twitches. Why would this be?
you may be measuring your TO4 on adductor pollicis which recovers later than the diaphragm
where do you place the black and red leads of nerve stimulator on adductor pollicis
- Distal (black lead) is placed at the level of the wrist on the ulnar surface of the flexor crease, as close to the nerve as possible
- The second or proximal lead (red) is placed 1-2 cm proximal to the first parallel to the flexor carpi ulnaris tendon
stimulation of the facial nerve that covers the eyelid and its response to NMB is similar to the adductor pollicis (eyelid squint)
Orbicularis oculi
stimulation of the facial nerve that covers the eyebrow is its response is similar to the laryngeal adductors with faster onset and more rapid recovery
Corrugator supercilii
stimulation of __________ is a good predictor of good intubating conditions and profound block
eyebrow
Orbicularis oculi is the________ branch of the facial nerve
zygomatic
Corrugtor supercilli is the_________ branch of the facial nerve
temporal
similar in depth, onset, and recovery as the larynx and the diagram… quicker than the upper airway
corrugator supercilli
which facial nerve stimulation is a good indicator that it is safe to intubate
corrugator supercilli
***** she said this in email
which facial muscle has similar recovery time to the adductor pollicis muscle
obicularis occuli
correct placement of electrodes to test corrugator supercilli
- 1st electrode (red)= outer canthus of eye
- 2nd electrode (black) = 2 cm below 1st & parallel with tragus of ear
2x dose to paralyze this than adductor pollicis
Diaphragm
which is more sensitive to a block:
laryngeal muscles/diaphragm vs. adductor pollicis
adductor pollicis
T or F: if the diaphragm is still moving, you won’t have twitches in adductor pollicis
F. not necessarily true, need 2x dose to paralyze the diaphragm
t or F: the face muscles are not a good indication of when to intubate but are a good indication of when to extubate
F- good indication for intubation, bad for extubation
medication that may “alter the rules” for the diaphragm vs adductor pollicis return of twitches
Succynylcholine (Anectine)
Neuromuscular blockade develops _______, lasts a ______ amount of time, and recovers _______ at the laryngeal and diaphragmatic muscles
Faster;
Shorter;
Faster.
The eyebrow muscle, corrugator supercilii, has a similar time course of recovery to the ___________
laryngeal adductors
where is the posterior tibial nerve
Located behind the medial malleolus
what does the posterior tibial nerve stimulate/ produce?
plantar flexion of big toe by contraction of flexor hallucis muscle
muscle twitch that is comparable to adductor pollicis
posterior tibial nerve
how to place the posterior tibial nerve leads
1st (black -) = 2 cm distal posterior to medial malleolus on foot
2nd (red+) = 2 cm above the malleolus - 1st
peripheral nerve stimulators deliver currents between
0 to 70 milliamperes (mA)
what do peripheral nerve stimulators have to decrease resistence
electrodes with silver-silver chloride
is a peripheral nerve stimulator a DC or AC
DC
is the Peripheral Nerve Stimulator a quantitative or qualitative monitoring tool
qualitative
in what two ways should you check peripheral nerve stimulator
visual & tactile
*** tactile encouraged
some issues you can run into with peripheral nerve stimulators
- improper placement = no nerve stimulation
- improper electrode placement
- obese patients
- skin resistance (hairy arm)
- takes time for optimal effectiveness.
***Surface electrodes don’t always stimulate ALL nerve fibers (unlike needle electrodes).
Increase stimulation from a single stimuli at _____ Hz (one every 10 seconds) to brief tetanic stimulation at ____ Hz causes sustained muscle contraction (tetanus) without fade
0.1
50
supramaximal muscles stimulation with peripheral nerve stimulator can cause what? and at what Hz is this
muscles fatigue
> 70-200 Hz
what can happen with repeated stimulation of peripheral nerve stimulator
fatigue
increased blood flow= increased delivery to stimulated muscle ESPECIALLY if stimulated BEFORE relaxant is given ***** Important
patterns of stimulation
Single Switch (ST)
Train-Of-Four (TOF)
Tetanus (TET)
Posttetanic Count (PTC)
Double Burst (DBS)
pattern of stimulation generally used for suggamedex
Posttetanic Count (PTC)
The two frequencies for the single twitch stimuli:
Frequencies between 0.1 Hz (1 stimulus every 10 seconds)
and 1.0 Hz (1 stimulus per second)
the least precise measure of peripheral nerve stimulation
Single Switch (ST)
** is a response to an individual stimuli.
T or F: single twitch stimulators are used to determine onset of block NOT recovery
True
T or F: single twitch does not require a baseline comparison
F - it does require baseline
name that nerve stimulator! – 4 Repetitive stimuli at 2 Hz (2/sec)
Train-Of-Four (TOF)
name that nerve stimulator! – Associated with fade in NDMR
Train-Of-Four (TOF)
minimum standard for determining extubation readiness on TOF
TOFr>/= 0.9
how do you express the relationship between the fourth vs 1st twitch in TOF:
fade ratio – T4/T1
No muscle relaxant = 1.0
Full muscle relaxation = 0
with 4 twitches on To4, you can still have _______% of receptors blocked by NMB
75
T or F - To4 can detect a phase I block
F- phase II block :)
30% To4 block, pt can
Head lift/hand grasp sustained
70-75% To4 block, pt can have
4 twitches on TOF, VC and TV can be normal
90% To4 block, pt can have
1 twitch on TOF, adequate relaxation of abdominal muscles
95% To4 block, pt can have
No twitches but the diaphragm may move
100% To4 block, pt can have
No response, flaccid, no TOF
TOF _____ to ______ indicates adequate surgical relaxations
0.15-0.25
fades or fatigues when partially blocked
Sensitive indicator of residual NMB.. repetitive >30Hz (usually 50Hz).
Tetanic Stimulation
*Use 5 second durations to evaluate neuromuscular function
Used in profound block and no TOF
5 second, 50 Hz tetanic stimulus followed 3 seconds later by a single-twitch stimuli at 1 Hz
Posttetanic Count (PTC)
Can help guide reversal especially with Sugammadex
Posttetanic Count (PTC)
Posttetanic Count (PTC) – with tetanus, it mobilizes ACh where
at prejunctional membrane so more is available @ endplate to get PT twitches
explain use of To4 in conjunction with PTC
to4 = 0, 50 Hz for 5 seconds –> depending on twitches after will tell you how soon you may get twitches back on to4.
2 twitches mean you got a while
8 twitches would mean you will get t04 response back soon
Two short bursts of tetanus at 50 Hz (each burst will have three impulses lasting 0.2 ms)
The two bursts are separated by 750 ms
double burst stimulation (DBS)
T or F: double burst stimulation (DBS) has better magnitude of muscle response than. to4
true
DBS can detect fade at a TOF of about_______
0.60
is depolarizing or nondepolarizing - “all or nothing” in reference to twitches/fade
depolarizing is all or nothing
a phase 1 block is preceded by
muscle fasciculation
Characterized by decrease in twitch tension, no fade during repeated stimulation (Tetanic or TOF) and no posttetanic potentiation
phase 1 block of depolarizing agent
what yields a phase II block of DMB
Fade develops in response to TO4
- Result of too much depolarizer or repeated use
true or false: phase 1 block T4/T1 ratio is 0.5 until all twitches disappear together
F- 1.0 not 0.5 bc no fade!
T or F: You should always check for twitches after using Succinylcholine before administering a nondepolarizing muscle relaxant
T
Onset and offset of block is faster in central muscles with a good blood supply, for example (name 2)
diaphragm and larynx
peripheral muscles, with a relatively poor blood supply, will have a slower onset of block and a longer recovery time – name an example
adductor pollicis
the muscles of the upper airway and pharynx behave similar to ________ muscles on onset and mirror _________ muscles in recovery.
central
peripheral
on induction and intubation, what is the ideal muscle to use and what is the most valuable stimulation pattern
- Corrugator Supercilli (FACE) or
(She said facial nerve as well).
- Single twitch or TOF stimulation
for maintenance of Anesthesia, what muscle stimulation will best reflect diaphragm:
Corrugator Supercilli
_______&______ monitoring are most useful during the profound neuromuscular block.
PTC and TOF
Before administering a neuromuscular antagonist, the TOF count should be at least
1 or 2
for Reversal and Recovery, monitoring what nerve stimulation is best option
adductor pollicis
true or false: peripheral nerve stimulators are a very precise way to measure return of muscle strength
F- suuuupppperrrrr unreliable bc its subjective
what it the best way to monitor the return of muscle twitch
Acceleromyography (AMG)
Acceleromyography (AMG):
- where
- what does it measure
- ______ based
- reading may be altered by ______
- ulnar nerve
- Measures acceleration of muscle response and converts it to a ratio
- TOFR based
- patient movement
Meds that can potentiate the actions of NMBDs and increase the difficulty of reversal (7):
- antibiotics (esp. aminoglycosides)
- loop diuretics
- mag sulfate
- lithium salts
- CCBs
- quinidine
- procainamide
Neuromuscular blockade develops _______, lasts a ______ amount of time, and recovers _______ at the laryngeal and diaphragmatic muscles
Faster;
Shorter;
Faster.
Central nerves (facial) are paralyzed faster and recover quicker than peripheral nerves (ulnar) (T/F)
True
Corrugator supercilii may show _______recovery but the adductor pollicis may show ________ recovery
complete; incomplete
the theory behind acceleromyography is based on:
Newtons second law of motion: force = mass x acceleration
