The onset of ablation of the evoked adductor pollicis muscle twitch in children: a clinical perspective

Abstract

The onset of ablation of the evoked adductor pollicis muscle twitch in children: a clinical perspectiveThe time to loss of the adductor pollieis muscle response to ulnar nerve stimulation at 1 Hz (twitch) after suceinylcholine, From the University of Michigan Medical Center, The Department of Anesthesiology, C.S. Matt Children's Hospital, Room C4139, Box 0800, Ann Arbor, MI 48109-0800.General anaesthesia is commonly induced in children by inhalation of an anaesthetic vapour in an oxygen/nitrous oxide mixture. Following induction of anaesthesia, an intravenous infusion is started and a muscle relaxant is administered to facilitate intubation and surgery. Previous work suggests that inhalation agents may affect the onset, potency, and duration of action of muscle relaxants. These conclusions have been based on studies which relied on controlled experimental conditions while measurements were made with special equipment. Clinical practice usually differs from those studios in thai clinical conditions rarely match those under which these drug effects were established. Laboratory grade equipment (mass or infrared spectrometry for end tidal agent detection, precision nerve stimulators, isometric force transducers with specialized armboards and recording equipment) is seldomly available or used in clinical practice. Anaesthetic depth becomes a matter of clinical judgement and simple, inexpensive equipment is used to assess neuromuscular transmission. No study to date has compared the results obtained under clinical conditions in children with those from controlled experiments. Thus, the clinician may wonder if, and how, his practice deviates from experimental observations. Therefore, we studied the onset time of twitch depression following administration of commonly used doses of succinylcholine and vecuronium during halothane, entlurane, and isoflurane anaesthesia in children. The duration of succinylcholine induced twitch depression was also studied. Clinical conditions were utilized while measurements were made with simple clinical tools. The results were compared with the times determined under controlled experimental conditions reported in the literature. MethodsThis study was approved by the Committee on Human Use of the University of Michigan. Subjects selected for this study were 2-13 years of age and of ASA physical status I or I1. They were free of known neuromuscular, cardiovascular, or renal disease and were scheduled to CAN 3 ANAESTH 1988 ! 35; 6 / t~9576-Sl)