Bench testing of pressure support ventilation with three different generations of ventilators

Objective: The new generations of intensive care ventilators tend to be more innovative and sophisticated than previous ones, but little is known about their respective performance for delivering pressure support ventilation (PSV) and how they compare to previous generations. Design: Active lung model bench test. Apparatus: Twenty-two commercially available ventilators classified into three categories: new generation ventilators (after 1993, n=7), previous generation (before 1993,n=6), and recent piston or turbine-based ventilators (n=9). Measurements and results: During PSV, the unloading efficacy of the assistance depends on the ventilator's ability to meet inspiratory flow demand. Three levels of flow (0.1 l/s, 0.6 l/s, and 1.2 l/s) were used to simulate inspiratory demand and the net area of the inspiratory airway pressure-time trace was calculated over the first 0.3 s, 0.5 s, and 1 s (Area _0.3, Area _0.5, and Area _tot) with three levels of PSV (5 cmH ₂O, 10 cmH ₂O, and 15 cmH ₂O). To assess the respective role of pressure support delivery and triggering function, triggering sensitivity was assessed independently by measuring the time delay (TD _tg) and the pressure fall (ΔPaw _tg) with two levels of inspiratory drive. All the new generation ventilators exhibited significantly better results than most of the previous generation ventilators regarding Area _0.3 and TD _tg, indicating large improvements in terms of triggering and pressurisation. Conclusion: Regarding PSV and trigger performance, the new generation ventilators - but also some piston and turbine-based ventilators - outperform most of previous generation ventilators.