Automating the control of fluid flow in a cardiac surgery simulator

We describe the implementation of a real-time control system that manages arrays of pumps, valves and pressure transducers as a subsystem of a simulator for cardiac surgery training. The subsystem is responsible for maintaining an appropriate fluid pressure in the aorta of the heart, and for circulating fluid around the heart, in a manner consistent with a cardiopulmonary bypass machine - both before and after the heart is placed on cardiopul-monary bypass. We highlight the role of abstraction in the development of the hardware interfaces, firmware and application level software that allow the operator of the simulator to effect the desired mode of fluid flow in the simulator.