Proportional assist ventilation versus pressure support ventilation in weaning ventilation: a pilot randomised controlled trial

Objective: Proportional assist ventilation with load adjustable gain factors (PAV+) is a mode of ventilation that provides assistance in proportion to patient effort. This may have physiological and clinical advantages when compared with pressure support ventilation (PSV). Our objective was to compare these two modes in patients being weaned from mechanical ventilation. Design: Prospective randomised controlled trial comparing PSV with PAV+. Setting: University-affiliated, tertiary referral intensive care unit (ICU). Participants: Mechanically ventilated patients on a controlled mode of ventilation for at least 24 hours, who were anticipated to be spontaneously ventilated for at least 48 hours after randomisation. Interventions: Nil. Main outcome measures: The primary outcome was time to successful liberation from the ventilator after the commencement of a spontaneous mode of ventilation. Secondary outcomes were requirement of rescue (mandatory) ventilation, requirement of sedative drugs, requirement for tracheostomy, re-intubation within 48 hours of extubation, ICU length of stay (LOS), hospital LOS, and ICU and hospital mortality. Results: 50 patients were randomised to either PSV (n = 25) or PAV+ (n = 25). There was no significant difference between the PAV+ and PSV groups in time to successful weaning (84.3 v 135.9 hours, respectively; P = 0.536). Four patients randomised to PAV+ were crossed over to PSV during weaning. There was no significant difference between groups for rescue ventilation, reintubation within 48 hours, tracheostomy, sedatives and analgesics prescribed, and ICU and hospital LOS. ICU mortality was higher in the PSV group (25% v 4 %; P = 0.002). Conclusions: Both modes of ventilation were comparable in time to liberation from the ventilator.