ANTAGONISM OF BLOCKADE PRODUCED BY ATRACURIUM OR VECURONIUM WITH LOW DOSES OF NEOSTIGMINE

The action of atracurium and vecuronium can be reversed readily by neostigmine 2.5 mg even when the degree of residual neuromuscular block-ade is considerable [1,2]. Thus, using the com-pound action potential of the electromyograph, Fox, Keens and Utting [1] showed that neo-stigmine 2.5 mg produced rapid reversal of resi-dual atracurium blockade if given when the recovery of the first response of the train-of-four (TOF) stimuli (A') was only 10 % of control (A) and that there was no advantage in using neo-stigmine 5 mg at this degree of block. Using an identical procedure, Jones, Hunter and Utting [2] reported similar results with vecuronium, again finding recovery to be as rapid with a dose of neostigmine 2.5 mg as with 5.0 mg. The results from these two studies suggested that doses of neostigmine less than 2.5 mg might be clinically effective. We have studied, therefore, the efficacy of neostigmine 1.25 mg and 0.625 mg in the antagonism of block produced by atracurium or vecuronium, in an attempt to assess if these lower doses of anticholinesterase were sufficient to produce prompt recovery. PATIENTS AND METHODS Permission for the study was granted by the hospital Ethics Committee and informed consent was obtained from each patient. Forty-five pat-ients (table I) were investigated; all were healthy and were scheduled to undergo general surgical or gynaecological procedures. They were allocate