[Continuous administration of mivacurium for short procedures. Delayed onset and recovery from neuromuscular blockade].

OBJECTIVE

To assess the delays of onset and spontaneous recovery from neuromuscular block produced by mivacurium administered by continuous infusion for short procedure requiring a deep relaxation.

STUDY DESIGN

Prospective open non comparative study.

PATIENTS

Twenty-nine class ASA I and II adults undergoing a stomatological procedure of short duration were included in the study.

METHOD

General anaesthesia was obtained with a continuous infusion of propofol, supplemented with alfentanil and N2O-O2 mixture. Neuromuscular blockade, assessed with electromyography of the adductor pollicis muscle, was obtained with mivacurium (150 micrograms.kg-1). After restoration of 5% of neuromuscular transmission, mivacurium was administered by continuous infusion in order to maintain a blockade between 91 and 99%.

RESULTS

The delay for decreasing twitch height by 95% was 2.9 +/- 1.0 min. The mean dose for maintenance of blockade was 10.9 +/- 1.5 micrograms.kg-1.min-1. The delay of spontaneous recovery from blockade was 10.2 min, 16.6 min and 21.3 min for obtaining 25, 75 and 95% twitchs respectively. The delay for the twitch increase from 25 to 75% was 6.6 min.

DISCUSSION

Mivacurium in continuous infusion provides rapidly a deep and stable neuromuscular blockade followed by a rapid spontaneous restoration of neuromuscular transmission in patients with normal pseudocholinesterases.