SERVO-CONTROLLED CLOSED-CIRCUIT ANAESTHESIA: A method for the automatic control of anaesthesia produced by a volatile agent in oxygen

摘要: A method of closed-circuit anaesthesia has been developed in which the end-tidal concentration volatile anaesthetic agent used is controlled automatically using a closed-loop servo system. End-tidal concentrations, measured by Engstrom EMMA, were maintained closed circuit direct liquid injection. The system was tested laboratory and clinical use (12 subjects). Accurate estimation uptake readily obtained results for halothane agreed closely with those previous workers. major sources error result zero offset EMMA turn caused humidity intrinsic characteristic simple proportional controller used. These errors easily correctable, could be to within 0.1%. Mean vapour at constant 0.8% 114 ml min−1 1 min, 36 5 29 10 min between 22 18 20–35 min.