Patient-ventilator interaction and sleep in mechanically ventilated patients: Pressure support versus proportional assist ventilation*

TLDR

The study aimed to determine whether proportional assist ventilation reduces patient‑ventilator asynchrony and improves sleep compared to pressure support ventilation during weaning from mechanical ventilation. In a randomized crossover trial of 13 ICU patients, polysomnography and respiratory measurements were recorded from 10 pm to 8 am while ventilator settings were adjusted to achieve a 50 % reduction in inspiratory work during spontaneous breathing trials. Proportional assist ventilation significantly improved sleep quality, reducing arousals and awakenings, increasing REM and slow‑wave sleep, lowering tidal volume and minute ventilation, and decreasing patient‑ventilator asynchronies, which correlated with fewer arousals.

Abstract

To understand the role of patient-ventilator asynchrony in the etiology of sleep disruption and determine whether optimizing patient-ventilator interactions by using proportional assist ventilation improves sleep.Randomized crossover clinical trial.A tertiary university medical-surgical intensive care unit.Thirteen patients during weaning from mechanical ventilation.Patients were randomized to receive pressure support ventilation or proportional assist ventilation on the first night and then crossed over to the alternative mode for the second night. Polysomnography and measurement of light, noise, esophageal pressure, airway pressure, and flow were performed from 10 pm to 8 am. Ventilator settings (pressure level during pressure support ventilation and resistive and elastic proportionality factors during proportional assist ventilation) were set to obtain a 50% reduction of the inspiratory work (pressure time product per minute) performed during a spontaneous breathing trial.Arousals per hour of sleep time during pressure support ventilation were 16 (range 2-74) and 9 (range 1-41) during proportional assist ventilation (p = .02). Overall sleep quality was significantly improved on proportional assist ventilation (p < .05) due to the combined effect of fewer arousals per hour, fewer awakenings per hour (3.5 [0-24] vs. 5.5 [1-24]), and greater rapid eye movement (9% [0-31] vs. 4% [0-23]), and slow wave (3% [0-16] vs. 1% [0-10]) sleep. Tidal volume and minute ventilation were lower on proportional assist ventilation, allowing for a greater increase in Paco2 during the night. Patient-ventilator asynchronies per hour were lower with proportional assist ventilation than with pressure support ventilation (24 +/- 15 vs. 53 +/- 59; p = .02) and correlated with the number of arousals per hour (R = .65, p = .0001).Patient ventilator discordance causes sleep disruption. Proportional assist ventilation seems more efficacious than pressure support ventilation in matching ventilatory requirements with ventilator assistance, therefore resulting in fewer patient-ventilator asynchronies and better quality of sleep.