Work of Breathing Imposed by Five Ventilators Used for Long-Term Support: The Effects of PEEP and Simulated Patient Demand

Abstract

Background

The imposed work of breathing (WOB_I has been shown to be excessive during spontaneous breathing through home-care ventilators that have not been fitted with an H-valve and external continuous flow. Our goal was to determine whether the performance of a prototype ventilator similar in size to home-care ventilators and purported to be easy to use is comparable to the performance of a widely used intensive care ventilator.

Methods

We measured the WOB_I, maximum inspiratory pressure (P_Imax), delay time, and pressure-time product (PTP) during simulated spontaneous breathing via a lung model. We compared the Aequitron LP-6 and LP-10, PLV-102, Puritan-Bennett 7200ae, and Bird TBird VS ventilators. We also measured pressure-rise time and pressure overshoot during pressure support ventilation with the 7200ae and TBird VS. Data were collected from 6 simulated spontaneous breaths for each system at 3 levels of tidal volume and inspiratory flow (200 mL at 30 L/min, 400 mL at 60 L/min, and 600 mL at 90 L/min).

Results

The WOB_I, P_max, time delay, and PTP were greater with the 3 home-care ventilators than with the 7200ae or TBird VS. Additionally, as patient demand increased, all inferences of the WOB_I increased. Performance of the TBird VS and of the 7200ae was similar although the TBird VS provided for a significantly lower P_Imax and PTP while having a faster pressure-rise time during pressure support ventilation.

Conclusion

Our results suggest that the WOB_I during spontaneous breathing via home-care ventilators is excessive, and as a consequence the intermittent mandatory ventilation (IMV) modes should not be used without modification. The TBird VS and 7200ae ventilators are superior to the home-care ventilators and have a low WOB_I.