Neuromuscular and Electromyographic Effects of Halothane and its Interaction with d-Tubocurarine in Man

Abstract

The effect of halothane (1-2 percent) on neuromuscular transmission and the abdominal electromyogram was studied in man. When electromyographic activity was markedly decreased and the abdomen sufficiently relaxed to permit lower abdominal surgery, there was no depression of the indirectly evoked twitch response. However, halothane increased the neuromuscular blocking action of both d-tubocurarine and hexofluorenium. The central nervous system depressant action of halothane and its ability to increase the action of d-tubocurarine are believed to account for the clinical observation that patients anesthetized with halothane require less d-tubocurarine for satisfactory muscle relaxation than do patients receiving nitrous oxide. It was pointed out in the discussion that the neuromuscular blocking action of halothane per se, which can be demonstrated in vitro, is attributable to desensitization of the postjunctional membrane.