Mechanical ventilation system utilizing bias valve

摘要

A portable mechanical ventilator having a ROOTS� blower is configured to provide a desired gas flow and pressure to a patient circuit. The mechanical ventilator includes a flow meter operative to measure gas flow produced by the ROOTS� blower and an exhalation control module configured to operate an exhalation valve connected to the patient circuit. A bias valve connected between the ROOTS� blower and the patient circuit is specifically configured to generate a bias pressure relative to the patient circuit pressure at the exhalation control module. The bias valve is further configured to attenuate pulsating gas flow produced by the ROOTS� blower such that gas flowing to the mass flow meter exhibits a substantially constant pressure characteristic. The bias pressure facilitates closing of the exhalation valve at the start of inspiration, regulates positive end expiratory pressure during exhalation, and purges sense lines via a pressure transducer module.