Canadian Journal of Anesthesia, Vol 38, 318-323, Copyright © 1991 by Canadian Anesthesiologists' Society

ARTICLES

Comparison of integrated evoked EMG between the hypothenar and facial muscle groups following atracurium and vecuronium administration

MD Sharpe, CA Moote, AM Lam and PH Manninen
Department of Anaesthesia, University Hospital, University of Western Ontario, London, Canada.

In 17 healthy patients undergoing O2.N2O.isoflurane anaesthesia, following atracurium or vecuronium administration, we compared simultaneous integrated evoked electromyograms (IEEMGs) during spontaneous recovery of the adductor digiti minimi (ADM) and orbicularis oris (OOM) muscle groups in response to train-of-four (TOF) stimulation of the ulnar and facial nerves, respectively. In all patients, the onset of neuromuscular recovery occurred first in the OOM. The time required to recover to a T4/T1 = 0.70 +/- 0.01 (SD) was earlier in the OOM compared with the ADM muscles in both the atracurium (33.4 +/- 5 vs 46.5 +/- 8, P less than 0.005) and vecuronium (46.5 +/- 12 vs 60.3 +/- 20, P less than 0.005) groups. When the OOM attained a T4/T1 = 0.70 +/- 0.01, the simultaneous T4/T1 in the ADM was 0.29 +/- 0.15 (P less than 0.05) in the atracurium group and 0.41 +/- 0.16 (P less than 0.01) in the vecuronium group. We conclude that (1) the facial muscles (OOM) recover earlier than the hypothenar muscles (ADM) and (2) an EMG T4/T1 = 0.70 in the facial muscles may not indicate adequate recovery of neuromuscular function.