Electronic Digital Computer Control of Ventilation and Anaesthesia

The use of a small digital computer to control a number of interactive physiological variables is demonstrated. It is shown that by monitoring the values of end tidal per cent CO 2 , inspired O 2 percentage and mean arterial blood pressure, a computer-controlled system can regulate the ventilation and anaesthesia of an animal within fine tolerances. Similarly it is shown that by controlling the infusion of muscle relaxant, the integrated electromyogram of a muscle can be maintained at any desired level. The computer control system automatically allows for random disturbances in system parameters in maintaining set levels of the controlled variables. The system responds rapidly to changes in the desired level of variables, and prescribed time courses of variables can be followed.