Miscellaneous monitors & equipment Flashcards
What is the BEST method of assessing a deep neuromuscular block?
a. sustained tetany
b. post-tetanic count
c. double burst stimulation
d. train-of-four
b. post-tetanic count
TOF delivers a series of
4 twitches at 2 Hz at 0.5 second intervals for 2 seconds
With TOF, the height
of the 4th twitch is compared to the height of the 1st twitch
Clinical recovery from neuromuscular blockade is achieved when the TOF ratio is
> 0.9 & a reversal agent is indicated when the TOF ratio <0.9
Tetanus delivers a
high frequency of stimulation
A common approach of tetany includes
a rapid sequence of 50 Hz stimuli for 5 seconds
Double burst stimulation delivers
2 short bursts of 50 Hz tetanus 0.75 seconds apart
_________ is easier to detect with DBS than it is with TOF
Fade
Post-tetanic potentiation occurs when the twitch response is
stronger after a tetanic stimulus than it was at baseline
To perform a post-tetanic count, a
50 Hz tetanic stimulus is delivered for 5 seconds followed by a series of single twitches
The best method of assessing deep neuromuscular blockade is
PTC
What percent of Nm receptors must be blocked to lose T1 (no twitches)?
90%
Fade occurs when the T4/T1 ratio is less than:
1.
Select the statement that BEST describes cerebral oximetry.
a. it is invasive
b. a >25% change from baseline suggests a reduction in cerebral oxygenation
c. it monitors arterial oxygen saturation in cerebral blood
d. it monitors global cerebral oxygenation
b. a >25% change from baseline suggests a reduction in cerebral oxygenation
Cerebral oximetry utilizes ________ to measure cerebral oxygenation
near-infrared spectroscopy (NIRS)
Cerebral oxygenation measures
venous oxygen saturation in the blood
Cerebral oximetry measures ___________– oxygenation
regional; it’s NOT a global monitor of cerebral oxygenation
_________ suggests a reduction in cerebral oxygenation
> 25% change from baseline
Where should the cerebral oximeter be placed
on the patient’s scalp, generally over the frontal lobe
The EEG provides information about the
electrical activity in the cerebral cortex
The EEG offers little information about the
subcortical structures, spinal cord or peripheral nerves
During anesthesia, the EEG waveforms typically change in two ways:
they become slower (lower frequency)
they become taller (higher amplitude)
_________ increases beta wave activity
Nitrous oxide
_______________- can increase epileptiform EEG activity
sevoflurane
__________- is NOT associated with epileptiform EEG activity
Etomidate
________________ may confuse EEG interpretation- the patient may be deeper than EEG suggests
Ketamine
Burst suppression occurs with
deep anesthesia but it can also cocur with hypothermia
Unilateral burst suppression is suggestive of
cerebral ischemia
Complete suppression (isoelectricity) occurs at
1.5-2 MAC
EEG monitoring is useful when
cerebral oxygenation is at risk
Examples of when EEG monitoring is useful include
carotid endarterectomy
deliberate hypotension
assessment of barbiturate coma
What are the classification of brain waves from high to low frequency?
Beta 13-30 cycles/sec
Alpha 8-12 cycles/sec
Theta 4-7 cycles/sec
Delta <4 cycles/sec
The development of _______________ during anesthetic maintenance may signify that the brain is at risk for ischemia
new delta waves
The following circumstances mimic cerebral ischemia:
deep anesthesia
hypothermia
hypocarbia
Beta waves are associated with
awake mental stimulation and “light” anesthesia
Alpha waves are associated with
awake but restful state with eyes closed
Theta waves are associated with
general anesthesia & children during normal sleep
Delta waves are associated with
general anesthesia
deep sleep
brain ischemia or injury
What three states mimic cerebral ischemia when monitoring the EEG?
deep anesthesia
hypothermia
hypocarbia
