USE OF NEOSTIGMINE IN THE ANTAGONISM OF RESIDUAL NEUROMUSCULAR BLOCKADE PRODUCED BY

Vecuronium has a shorter duration of action than pancuronium and recovery from neuromuscular blockade is more rapid with the newer drug (Crul and Booij, 1980). It has been suggested that, when given in bolus doses, an anticholinesterase may not be necessary to antagonize vecuronium-induced neuromuscular block (Baird, Bowman and Kerr, 1982), although when the agent is given by infusion, neostigmine is required in a dose similar to that needed after an infusion of pancuronium (Gencarelli and Miller, 1982). Using the train-of-four (TOF) method of stimulation, and recording electromyographically, antagonism of neuromuscular block after bolus doses of vecuronium has been studied, using both a larger (5.0-mg) and a smaller (2.5-mg) dose of neostigmine. The basic plan of the study was similar to that of Fox, Keens and Utting (1987). A study using tetanic rates of stimulation has suggested that a large dose of neostigmine may itself cause neuromuscular blockade (Payne, Hughes and Al Azawi, 1980). Signs of increased blockade using the TOF were, therefore, sought, —especially when the larger doses of neostigmine were given to those with the least degree of block. PATIENTS AND METHODS Following approval by the hospital ethics com-mittee, informed consent was obtained from 50 patients undergoing general or gynaecological surgery. All patients were graded as ASA I or II and were free from any neurological disorder. Patients were randomly allocated to one of five groups. In the first group of 10 patients, sponta