Time to antagonism induced by pyridostigmine from different levels of neuromuscular blockade was evaluated in 45 patients anesthetized with nitrous oxide, fentanyl, and vecuronium. Neuromuscular blockade, as monitered by train-of-four count, was
antagonized at varing degrees of spontaneous recovery.
Train-of-four ratio was used as an index of the ability of the patients to maintain adequate spontaneous ventilation, and maximum inspiratory pressure as an index of the ability of the patients to protect their airways against aspiration or
obstruction.
We measured time from administration of pyidostigmine to train-of -four ration of 70% indicating the recovery of the ability to maintain adquate spontaneous ventilation, and time to maximum inspiratory pressure of 45cmH2O indicating the recovery
of
the
ability to protect the patients' airways against aspiration or obstruction. For a train-of -four count level of 0~1, reversal time to train-of-four ration of 70% was 22.73±3.00 minutes and that to maximum inspiratory pressure of -45 cmH2O was
30.33±2.69 minutes .For a train-of -four count level of 2~3, reversal time to train-of-four ratio of 70% was 17.33±3.18 minutes and that to maximum inspiratory pressure of -45cmH2O was 22.27±2.91 minutes For a train-of-four count level of 4,
reversal
time to train-of-four ration of 70% was 8.40±3.58 minutes and that to maximum inspiratory pressure of -45 cmH2O was 14.60±3.11 minutes.
It is concluded that the more shallow is the neuromuscular blockade, the more rapid and the safer is the reversal of neuromuscular blockade, although the doe of reversal drug was determined according to the depth of neuromuscular blockade.
Moreover, it should take more than 30 minutes to antagonize profound neuromuscular blockade induced by vecuronium to such a degree that not only can the patients maintain adequate spontaneous ventilation, but they can maintain the airways and
protect
them against aspiration as well.
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