ASSISTED VENTILATION Randomised crossover study of pressure and volume non-invasive ventilation in chest wall deformity

Background: Non-invasive ventilation is an established treatment for chronic respiratory failure due to chest wall deformity. There are few data available to inform the choice between volume and pressure ventilators. The aim of this study was to compare pressure and volume targeted ventilation in terms of diurnal arterial blood gas tensions, lung volumes, hypercapnic ventilatory responses, sleep quality, and effect on daytime function and health status when ventilators were carefully set to provide the same minute ventilation. Methods: Thirteen patients with chest wall deformity underwent a 4 week single blind randomised crossover study using the Breas PV403 ventilator in either pressure or volume mode with assessments made at the end of each 4 week period. Results: Minute ventilation at night was less than that set during the day with greater leakage for both modes of ventilation. There was more leakage with pressure than volume ventilation (13.8 (1.9) v 5.9 (1.0) l/min, p = 0.01). There were no significant differences in sleep quality, daytime arterial blood gas tensions, lung mechanics, ventilatory drive, health status or daytime functioning. Conclusions: These data suggest that pressure and volume ventilation are equivalent in terms of the effect on nocturnal and daytime physiology, and resulting daytime function and health status.