Equipment Refractoriness of neuromuscular determination by computer subtraction of neurally evoked compound

Shortly after elicitation of a muscle response by supramaximal stimulation of its motor nerve, there exists a period of refractoriness of neuromuscular transmission when a second stimulation elicits only a submaximal response or no response at all. Many anaesthetics and neuromuscular blocking and facilitatory drugs change the refractoriness of neuromuscular transmission. Measurement of this refractoriness may improve our understanding of the neuromuscular actions of these drugs and be useful in differential diagnosis. However, the neuromuscular refractory periods (RP) are difficult to measure, and the unavailability of normal values renders accurate determination of drug effects impossible. Based on an existing technique of digitization and time expansion of the neurally evoked compound electromyogram (ncEMG), we developed a computer programme of waveform subtraction, and determined in nine