OBJECTIVE: In a bench study, we sought to evaluate the influence of regulation of pressurization rate (PR) on the imposed work of breathing (W(I)) and inspiratory flow (V̇(I)) pattern during pressure support ventilation (PSV). METHODS: A commercially available mechanical ventilator (Bear 1000) was connected to an active lung simulator; the ventilator was set with PEEP at 10 cm H2O and pressure support at 10 cm H2O above PEEP. Three different PR levels (-5, 0, and +5, arbitrary units) were tested at 2 different levels of inspiratory 'effort' (mean V̇(I) 0.45 and 0.9 L · s- 1). The time from the onset of inspiratory effort to inspiratory flow delivery (t(V̇(I))) and its pressure-time product per minute (PTP1), the pressure-time product from the onset of V̇(I) (PTP2), the duration of the below-PEEP phase of the respirator) circuit pressure (t(P=0)) and the area of the pressure-volume curve below PEEP (W(I)) were measured as well as peak inspiratory flow (PIF) and the time to reach it (t(PIF)). RESULTS: No statistically significant differences in t(V̇(I)) and PTP1 were observed among different PRs. On the contrary, PTP2, t(P=0), and W(I) were significantly reduced by PR adjustment. This variation was more pronounced with the higher inspiratory drive. At the same time, PIF was increased and t(PIF) shortened. CONCLUSION: Adjustments in PR can reduce imposed work of breathing during assisted spontaneous breaths and may improve patient comfort. Its regulation should be individually tailored to inspiratory effort and flow in each patient.
|Number of pages||5|
|Publication status||Published - Oct 1996|
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine