EFFECT OF SUXAMETHONIUM GIVEN DURING RECOVERY FROM ATRACURIUM

At the end of an abdominal operation, muscle relaxation may be inadequate and a transient increase in block may be needed to facilitate closure. Suxamethonium is the only agent of short duration available currently [1] and has been used in these circumstances. Whilst interactions with long acting competitive agents have been des-cribed [2-5], there are no descriptions of its effect on recovery from the block produced by atra-curium. This study was designed to assess the effects of increasing doses of suxamethonium on the recovery of block produced by atracurium and on the subsequent interaction with neostigmine. PATIENTS AND METHODS Thirty-eight patients (18-70 yr, 45-110 kg) under-going elective surgical procedures were studied after they had given informed consent. No patient who had received aminoglycoside antibiotics was studied. The study was approved by the local Ethics Committee. Diazepam 10-20 mg and metoclopramide 10 mg were given by mouth 1 h before anaesthesia was induced with thiopentone 4-6 mg kg"1 and fentanyl 2 —4ugkg~1. Anaesthesia was main-tained with 66 % nitrous oxide and 0.5 % en-flurane in oxygen supplemented by additional doses of fentanyl and thiopentone as required. End-tidal carbon dioxide tension was maintained at 4-5 kPa. The integrated, rectified and gated electro-myographic response of the hypothenar muscles was recorded in response to supramaximal train-• of-four stimuli delivered to the ulnar nerve at 20-s intervals using a Datex Relaxograph. Contro