A simple ventilator suitable for respiratory gas studies.

A simple ventilator is described where a spring-loaded bellows is filled from a compressed gas supply. The outflow from the bellows to the subjects is controlled by solenoid valves. The device is a minute volume divider and the durations of inspiration and expiration are set by timers that operate the solenoid valves. The valves are positioned near the subject to minimize dead space and gas compression effects. Precise valve timing ensures separation of inspirate and expirate. The ventilator is suitable for respiratory gas studies on animals and may be modified for human use if required.