Neuromuscular Blockade Monitoring Flashcards
What is single supramaximal stimulus, and what is it used for?
1 Hz to 0.1 Hz (one every second to one every 10 seconds)
The response is proportional to frequency
It does not have much clinical application as it will tell you only if a patient is paralysed or not (no information on degree of paralysis).
Four supramaximal stimulati over 0.5 seconds (2 Hz) purpose?
‘Fade’ can be observed and provides basis of evaluation
This pattern of stimulation is used to assess the intensity of blockade (1-2 twitches is appropriate for abdominal surgery)
Reversal agents can be administered if the train of four (TOF) count is 1-2 twitches with medium length acting neuromuscular blocking agents.
TOF ratio: uses
This is the ratio of the amplitude of 4th twitch to the amplitude of 1st twitch.
With non-depolarising block the ratio decreases and is inversely proportional to degree of block; this allows objective measurement of residual neuromuscular blockade.
The ratio (measured by accelerography) needs to be between 0.7 and 0.9 enable adequate reversal.
What is - Post-tetanic twitch count?
50 Hz for 5 seconds, more than a 3 second pause, then a single twitch stimulus at a frequency of 1 Hz.
This pattern of stimulation is used to assess deep blockade when the TOF count is zero (that is, in neurosurgery, microsurgery or ophthalmic surgery when even small movements of a patient will disturb the surgical field).
How is post-tetanic twitch count stimulation used?
It gives an approximate time to return of response to single twitches and hence permits assessment of block too deep for any other technique.
PTC of 2 by palpation suggests no twitch response for about 20-30 minutes.
PTC of 5 about 10-15 minutes.
What is double burst stimulation?
Two short bursts of 50 Hz separated by 750 msec
This pattern of stimulation is used to manually (tactile) assess small amounts of residual blockade.
