Abstract PR088

Abstract

Background & Objectives: Proportional Assist Ventilation (PAV+) delivers positive pressure ventilation in proportion to instantaneous inspiratory effort, with some studies suggesting PAV+ may reduce ventilator dyssynchrony and the duration of weaning from the ventilator. This trial compared the time taken to wean critically ill patients from invasive mechanical ventilation using PAV+ as opposed to Pressure Support Ventilation (PSV). Secondary objectives were to compare the rate of tracheostomy, failed extubation, ICU and hospital length of stay (LOS), ICU and hospital mortality in patients studied. Materials & Methods: This study was conducted in a 15-bed Australian metropolitan ICU that admits approximately 1100 medical and surgical patients per year. Patients were included in the study if they had been ventilated on a controlled mode of ventilation and were deemed suitable for at least 48 hours of weaning on a spontaneous mode of ventilation. Patients were excluded if they were unlikely to survive for 24 hours, had a neuromuscular disease or injury, or a tracheostomy in-situ. Results: Fifty patients were randomised, with 25 randomised into each arm. There was no statistical difference in age (median = 65 vs 61 years; p = 0.76) and APACHE-III illness severity score (median = 76 vs 77.5, p = 0.75) between the PAV+ and PSV groups. There was no significant difference in the duration of weaning from mechanical ventilation (78.2 vs 130.5 hours; p = 0.53). There was a non-significant trends towards lower in-hospital mortality (12% vs 37.5%, p = 0.08). There was no significant difference in the ICU LOS (median = 9.3 vs. 11.8 days; p = 0.57) among patients in the PAV+ arm when compared to those in the PSV arm. Three patients in the PAV+ group did not respond to this ventilation mode and were changed to PSV. There was no significant difference in the proportion of patients requiring tracheostomy (20% vs 29.2%; p = 0.68) or reintubation (4% vs 8.3%; p = 0.97). Conclusion: The duration of weaning from mechanical ventilation was comparable with PAV+ and PSV ventilation. A trend towards reduced hospital mortality was noted with PAV+ weaning. A larger study may provide further information on the advantages and disadvantages of PAV+ compared to other modes of spontaneous ventilation.