Inaccuracy of tidal volume delivered by home mechanical ventilators.

Ideally, the inspired (tidal) volume (V(T)) provided by a volume-controlled ventilation device should not change when the pressure imposed on the ventilator varies. A bench study evaluation of V(T) versus pressure was performed on 10 commercially available devices. The difference between the desired V(T) and the observed V(T) reached 100 mL for some devices when inspiratory resistance was at its lowest, rising to 150 mL when inspiratory resistance was increased to obtain peak airway pressure of 60 cmH2O. The present data indicate that some home ventilators are inaccurate in delivering the preset tidal volume when the pressure imposed on the ventilator is increased to simulate high airway resistance.