Physiological Study of 4 Modified Self-Contained Ventilators. Evaluation of the Impact 87G Self-Contained Ventilator
Final rept. 1 Apr-31 Dec 1992
UNIFORMED SERVICES UNIV OF THE HEALTH SCIENCES BETHESDA MD
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We evaluated the performance of four Impact model 780 self-contained ventilators before and after vibration testing. Units were tested using the internal compressor and external compressed air powered ventilation modes. We measured impedances to air flow of the input and output ports, the spontaneous inspiration circuit, and the C-2 air filter, and determined the ventilatory parameters including minute ventilation, tidal volume, mean delivered flow rate, insufflation time, exhalation time, and duty cycle. We also determined battery life under the different operating modes. There was relatively little difference in the ventilatory performance of the four different units. The only variable that changed significantly in response to vibration was insufflation time, with a corresponding change in duty cycle. In all four units, the exhalation ports leaked outward during insufflation. All filter connectors leaked unfiltered air inward during spontaneous inspiration and during powered ventilation with the compressor. The average resistance of the four units to inspiratory airflow during spontaneous breathing was 26.5 cm H20Lsec, a value that would probably make spontaneous inspiration through the ventilator impossible for a person with impaired pulmonary function. Mechanical ventilation.
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