Peripheral Nerve Stimulator Flashcards
What are the three factors that determine the response
of peripheral nerves to electrical stimulation?
- Placement of electrodes 2. Current applied 3. Duration of
current
Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Stock MC,
Ortega R. Clinical Anesthesia. 7th ed. Philadelphia, PA:
Lippincott Williams and Wilkins; 2013: 543.
Between current, voltage, and frequency, which is the
determining factor in nerve stimulation?
Current is the determining factor in nerve stimulation.
Dorsch JA, Dorsch SE. A Practical Approach to Anesthesia
Equipment. Philadelphia, PA: Lippincott Williams and Wilkins,
2011: 501.
What is the simplest method of nerve stimulation?
The single twitch. The single twitch is elicited by the application of
a single stimulus every second, every 10 seconds, or manually at
0.1 to 1 HZ for 0.1 to 0.2 ms. This mode of stimulation has limited
clinical usefulness.
Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Stock MC,
Ortega R. Clinical Anesthesia. 7th ed. Philadelphia, PA:
Lippincott Williams and Wilkins; 2013: 543.
Define train-of-four (TOF).
The TOF is 2 Hz stimulation of a series of four twitches applied
every half-second for a total of 2 seconds. You should wait at
least 10-12 seconds between assessments.
Nagelhout JJ, Plaus KL. Nurse Anesthesia. 5th ed. St. Louis,
MO: Elsevier Saunders Company; 2014: 161.
How is the posttetanic count elicited?
A 50-Hz 5 sec tetanic stimulation is applied, there is a 3 second
pause, followed by 1-Hz single twitch stimulations applied in a
series.
Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Stock MC,
Ortega R. Clinical Anesthesia. 7th ed. Philadelphia, PA:
Lippincott Williams and Wilkins; 2013: 544.
What is the purpose of the posttetanic count?
During profound neuromuscular blockade, the posttetanic count is
used to estimate the time that is required before a response to
stimulation will return. The number of visible twitches correlates
inversely with the amount of time required for return of the first
twitch of a TOF stimulation
Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Stock MC,
Ortega R. Clinical Anesthesia. 7th ed. Philadelphia, PA:
Lippincott Williams and Wilkins; 2013: 544.
What is tetany? How and why is it performed?
Tetany is the application of a rapidly repeating stimulus (50 Hz,
100 Hz, or 200Hz). If there is no nondepolarizing muscle
blockade, it will cause a sustained contraction of the stimulated
muscles. If a nondepolarizing block is present, the contraction
response will fade (the muscles will not sustain the contraction).
50 Hz is most commonly used because it most closely simulates a
maximal voluntary effort.
Dorsch JA, Dorsch SE. A Practical Approach to Anesthesia
Equipment. Philadelphia, PA: Lippincott Williams and Wilkins,
2011: 505.
Define double-burst stimulation.
Double-burst stimulation consists of two short 50-Hz tetany that
are separted by 750 msec. The TOF ratio correlates closely with
the double-burst stimulation ratio.
Nagelhout JJ, Plaus KL. Nurse Anesthesia. 5th ed. St. Louis,
MO: Elsevier Saunders Company; 2014: 161.
When four responses are present on TOF stimulation,
how long can one anticipate sufficient recovery to be
achieved with reversal of neostigmine? Edrophonium?
5 minutes with neostigmine and 2-3 minutes with edrophonium
Nagelhout JJ, Plaus KL. Nurse Anesthesia. 5th ed. St. Louis,
MO: Elsevier Saunders Company; 2014: 164.
Why is the choice of muscle important in monitoring
neuromuscular blockade?
Neuromuscular blocking agents affect muscles in a non-uniform
way. It is important to choose a monitoring site that responds
closely to the involved muscles of interest.
Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Stock MC,
Ortega R. Clinical Anesthesia. 7th ed. Philadelphia, PA:
Lippincott Williams and Wilkins; 2013: 545.
Would the adductor pollicis muscle be an appropriate
choice to stimulate in order to determine adequate
relaxation for intubation?
No. Monitoring the facial nerve reflects readiness for intubation.
Nagelhout JJ, Plaus KL. Nurse Anesthesia. 5th ed. St. Louis,
MO: Elsevier Saunders Company; 2014: 164.
Describe the progression of paralysis following the
administration of neuromuscular blocking agents
Eye muscles are the first to be paralyzed, the extremities are
affected next, followed by the trunk, abdominal muscles, and
lastly, the diaphragm. Recovery is restored in reverse order.
Nagelhout JJ, Plaus KL. Nurse Anesthesia. 5th ed. St. Louis,
MO: Elsevier Saunders Company; 2014: 164.
Where would recovery from neuromuscular blockade
best be monitored?
The ulnar nerve
Nagelhout JJ, Plaus KL. Nurse Anesthesia. 5th ed. St. Louis,
MO: Elsevier Saunders Company; 2014: 164.
