A low oxygen consumption pneumatic ventilator for emergency construction during a respiratory failure pandemic

Williams, D.; Flory, S.; King, R.; Thornton, M.; Dingley, J.

The UK influenza pandemic plan predicts up to 750 000 additional deaths with hospitals prioritising patients against inadequate resources. We investigated three prototype low‐cost, gas‐efficient, pneumatic ventilators in a test lung model at different compliance and rate settings. Mean (SD) oxygen consumption was 0.913 (0.198) and 1.119 (0.267) l.min(−1) at tidal volumes of 500 ml and 700 ml respectively. Values of F (I) o (2) increased marginally as lung compliance reduced, reflecting the increased ventilator workload and consequent increased enrichment of breathing gas by waste oxygen from the pneumatic mechanism. We also demonstrated that a stable nitric oxide concentration could be delivered by this design following volumetric principles. It is possible to make a gas‐efficient ventilator costing less than £200 from industrial components for use where oxygen is available at 2‐4 bar, with no pressurised air or electrical requirements. Such a device could be mass‐produced for crises characterised by an overwhelming demand for mechanical ventilation and a limited oxygen supply.