Microcomputer-based muscle relaxation monitor and controller for clinical use

The paper describes the design and performance of a microcomputer-based system to measure and control the level of muscle relaxation during surgical procedures. A measurement system feeds the twitch response to a train-of-four stimulation pulses into a microcomputer system. The microcomputer determines the level of muscle relaxation and then calculates, according to a specified control algorithm, the minimum amount of drug necessary to achieve adequate relaxation as rapidly as possible. The drug is administered automatically to the patient in the form of bolus injections by a motordriven syringe unit on instruction from the microcomputer. This controller system has been used in 42 clinical trials using d-tubocurarine and has proved to be capable of successfully controlling muscle relaxation.