Noninvasive proportional assist ventilation for acute respiratory insufficiency - Comparison with pressure support ventilation

Noninvasive positive pressure ventilation (NPPV) is usually applied using p ressure support ventilation (PSV). Proportional assist ventilation (PAV) is a newer mode that delivers assisted ventilation in proportion to patient e ffort. We hypothesized that PAV for NPPV would support gas exchange and avo id intubation as well as PSV and be more comfortable and tolerable for pati ents. Adult patients with acute respiratory insufficiency were randomized t o receive NPPV with PAV delivered using the Respironics Vision ventilator o r PSV using a Puritan-Bennett 7200ae critical care ventilator. Each mode wa s adjusted to relieve dyspnea and improve gas exchange until patients met w eaning or intubation criteria, died, or refused to continue. Twenty-one and 23 patients were entered into the PAV and PSV groups, respectively, and ha d similar diagnoses and baseline characteristics, although pH was slightly lower in the PAV group (7.30 versus 7.35, p = 0.02). Mortality and intubati on rates were similar, but refusal rate was lower, reduction in respiratory rate was more rapid, and there were fewer complications in the PAV group. We conclude that use of the PAV mode is feasible for noninvasive therapy of acute respiratory insufficiency. Compared with PSV delivered with the Puri tan-Bennett 7200ae, PAV is associated with more rapid improvements in some physiologic variables and is better tolerated.