THE EFFECT OF STABILIZATION ON THE ONSET OF NEUROMUSCULAR BLOCK WHEN ASSESSED USING ACCELEROMETRY

Accelerometry is increasingly being used for neuromuscular monitoring. We sought to determine whether this system is sensitive to the period of stabilization of muscle twitch prior to the administration of neur omuscular relaxant. We recruited 20 patients. No premedication was giv en, and anesthesia was induced with propofol and alfentanil and mainta ined by a propofol infusion. An accelerometer was attached to each wri st. One of the ulnar nerves was stimulated for 20 min and the other fo r 3 min using a train-of-four pattern at 15-s intervals. Ten patients then received vecuronium 0.1 mg/kg and a subsequent 10 received atracu rium 0.5 mg/kg. The time to onset of maximum block was recorded. The d ata collected was subjected to a paired t-test with P < 0.05 taken as significant. The mean onset times for patients who received vecuronium was 148.5 s for the arms stabilized for 3 min and 151.5 s for the arm s stabilized for 20 min, and in those who received atracurium it was 1 38.0 s and 130.5 s, respectively. We conclude that there is no signifi cant difference in the onset of neuromuscular block with either vecuro nium or atracurium after stabilization periods of 3 or 20 min when ass essed by accelerometry.