Use of a Peripheral Nerve Stimulator During Reversal
of Neuromuscular Blockade
Antagonism of a nondepolarizing neuromuscular block should not
be initiated before at least two responses to TOF stimulation can be felt or before
obvious clinical signs of returning neuromuscular function are present. To achieve
rapid reversal (within 10 minutes) to a TOF ratio of 0.7 in more than 90% of patients,
three and preferably four responses should be present at the time of neostigmine
injection.[108]
It is not possible to achieve a
TOF ratio of 0.9 in all patients using this method, but critical episodes of postoperative
residual block should be an infrequent occurrence.[109]
During recovery of neuromuscular function, when all four responses
to TOF stimulation can be felt, an estimation of the TOF ratio may be attempted.
However, manual (tactile) evaluation of the response to TOF stimulation (see Fig.
39-8
) is not sensitive enough to exclude the possibility of residual neuromuscular
blockade.[29]
[104]
[110]
Greater sensitivity is achieved with DBS3,3
,
but even absence of manual fade in the DBS3,3
response does not exclude
clinically significant residual blockade.[33]
Therefore,
manual evaluation of responses to nerve stimulation should always be considered in
relation to reliable clinical signs and symptoms of residual neuromuscular blockade
( Table 39-3
).
