A fluidically-operated respirator comprises an apneic event circuit (10) and a demand gas circuit (20). The apneic event circuit (10) comprises a variable capacitance device (132) and an exhaust means (130) which rapidly discharge fluid from the circuit (10) when an inspiration occurs. If an apneic event...http://www.google.co.uk/patents/US4484578?utm_source=gb-gplus-sharePatent US4484578 - Respirator apparatus and method
