The imposed inspiratory work of breathing with mechanical ventilators designed for critical care has been extensively studied. However, no data concerning imposed inspiratory work of breathing using home care ventilators has been published. METHODS AND MATERIALS: We measured the imposed inspiratory work of breathing and the maximum negative pressure deflection during spontaneous inspiration with five home care ventilator systems, using a lung model. The Aequitron LP-6, Puritan-Bennett 2800, Lifecare PLV-100, Bear Medical 33, and Medimax ARF-1500E home care ventilators with standard circuits were compared to the Lifecare PLV-100. The PLV-100 was equipped with a one-way H-valve between the ventilator and humidifier that allowed spontaneous breathing from atmosphere or from a reservoir setup, and avoiding the ventilator's internal circuitry. Data were collected from six simulated spontaneous breaths for each system, at various peak inspiratory flowrates with three humidification systems (bubble-through, pass-over, and heat-and-moisture exchanger). RESULTS: Imposed inspiratory work of breathing and maximum negative pressure deflection increased as peak flow increased and with increased resistance to inspiration (bubble-through > exchanger > pass-over). The imposed inspiratory work of breathing and maximum pressure deflection were significantly greater with all systems when compared to the H-valve modifications with either the pass-over or the heat-and-moisture exchanger humidifiers. CONCLUSION: As a result of the increased inspiratory work of breathing observed in the five home care ventilators during simulated spontaneous breathing, we caution against the use of these home care ventilators in the SIMV mode unless appropriate circuit modifications are made .
Kacmarek et al. (Tue,) studied this question.