ES352709A1 - Improvements in or relating to Automatic Ventilators - Google Patents

Abstract

A volumetric respirator providing an adjustable ventilation volume and separately regulated inspiration and expiration times comprises an admission chamber 6, a reversal chamber 10 and an intermediate chamber 8 vented to the ambient atmosphere at 9 all with volumes variable by movement of the pistons 2 and 4. Piston 2 carries a sealing member 13 for shutting off the inlet 12, which is connected to a source of pressurised air, and a pipe 7, 31 with a constrictor device 32 leads to the patient. A branch pipe 20 upstream of the constrictor communicates ultimately with the reversal chamber by a passage 17, 27, 11 having a constructor-28 associated with a double-acting, non-return valve comprising a sealing member 18 biassed to prevent flow through the passage 20, 17, 27, 11 by a spring-loaded plate 23 (as in Fig. 2, not shown) but which, in its other position (as in Fig. 1), prevents back flow. In operation, the inspiration time is governed by the constrictor 32 and the expiration time is adjusted by means of constrictors 28 and 30, the latter regulating the rate of venting to the atmosphere of the pressure on the other side of the sealing member 18, i.e. the pressure in the reversal chamber 10. A modified apparatus is described with reference to Figs. 3 and 4 (not shown) which employs two spring-loaded non-return valves (33 and 34) in place of the device shown in Fig. 1 and incorporating conventional associated features including a phase indicator, flow-meter, and expiration collector in addition to a regulated, venturitype, injector operating intermittently to promote the outflow of air to assist the respiring phase, the air supply for the venturi being derived from the pressurised air source in front of the admission chamber and passes through a needle valve which is closed by the downstroke of the piston 4 as it reduces the volume of the reversal chamber. Fig. 5 (not shown) depicts a modified admission-reversal chamber unit comprising two displaceable membranes with an interposed support in place of the sliding pistons shown.