Clinical use of peripheral nerve stimulators

Abstract

Evaluation of degree of neuromuscular blockade during anaesthesia is often based solely upon clinical observations such as occurrence of spon- taneous movements, bucking and swallowing, or testing of clinical signs such as the ability to open eyes and sustain headlift. The clinical evaluation is, however, not always adequate. Thus, in two studies on the frequency of residual curarisation in the recovery room it was found that the neuro- muscular blockade was insufficiently reversed in 24-44% of patients given a non-depolarizing relax- ant and not monitored with a nerve stimulator dur- ing anaesthesia11 ,21. The increased awareness of the risk of residual curarisation and the development of the new non- depolarizing relaxants, Atracurium and Vecuronium, with a rapid spontaneous recovery rate, have increased the interest in simple methods for evaluation of neuromuscular blockade. Equip- ment for mechanical and electromyografic (EMG) monitoring of the response to nerve stimulation has become commercially availableI3.41. Unfortunately, this equipment is expensive and rather cumber- some to use in daily clinical routine. However, one can manage quite well without such sophisticated equipment, Le. with only a nerve stimulator. The purpose of this review article is to discuss the principles of peripheral nerve stimulation and the clinical use of nerve stimulators without recording equipment.