Accuracy of delivered versus preset minute ventilation of portable emergency ventilators.
The accuracy of delivered minute volume (VE) ventilation of portable emergency ventilators (PEV) was evaluated. Five PEV from three manufacturers were adapted to an artificial lung for varying compliance and resistance. Each PEV was tested in the "no airmix" (pure oxygen) and "airmix" (approximately 60% oxygen) setting at different frequencies and VE. Measurement of delivered VE (VEdel) was made using a pneumotachograph and digital integration of the flow values greater than 1 min (maximal error +/- 2%). Maximal inspiratory pressure (Pinsp) was measured with a transducer. Two PEV from one manufacturer produced severe hyperventilation when used at low VE (i.e., in children). Two other PEV from another manufacturer produced less marked hyperventilation, but revealed unexpected hypoventilation during conditions of higher inspiratory pressures (i.e., in adults with reduced compliance). The prototype PEV that was tested also revealed less marked hyperventilation with small decreases (down to -10% of the VE at higher Pinsp values). Further investigation is needed before this prototype goes into production. Manufacturers should redefine predicted values or machine settings or indicate that use of these devices may produce results which are not in accordance with the machine settings. Until adjustments are made, ventilation should be monitored when possible by measurement of end-tidal PCO2 or systemic arterial blood gases.
Heinrichs
W
W
Department of Anesthesiology, Johannes Gutenberg-University Mainz Medical School, FRG.
Mertzlufft
F
F
Dick
W
W
D000328:Adult; D002648:Child; D004630:Emergencies; D005069:Evaluation Studies as Topic; D006801:Humans; D006985:Hyperventilation / Q000209:etiology; D007040:Hypoventilation / Q000209:etiology; D012122:Ventilators, Mechanical / Q000009:adverse effects*