Patient-ventilator interaction and sleep in mechanically ventilated patients: pressure support versus proportional assist ventilation.
OBJECTIVE
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.


METHODS
Randomized crossover clinical trial.


METHODS
A tertiary university medical-surgical intensive care unit.


METHODS
Thirteen patients during weaning from mechanical ventilation.


METHODS
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.


RESULTS
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).


CONCLUSIONS
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.
Bosma
Karen
K
Dipartimento di Anestesiologia e Rianimazione, Università di Torino, Ospedale S. Giovanni Battista-Molinette, Torino, Italy.
Ferreyra
Gabriela
G
Ambrogio
Cristina
C
Pasero
Daniela
D
Mirabella
Lucia
L
Braghiroli
Alberto
A
Appendini
Lorenzo
L
Mascia
Luciana
L
Ranieri
V Marco
VM
D000328:Adult; D000368:Aged; D001143:Arousal; D018592:Cross-Over Studies; D005260:Female; D006785:Hospitals, University; D006801:Humans; D007362:Intensive Care Units; D008027:Light; D008297:Male; D008875:Middle Aged; D009622:Noise; D017286:Polysomnography; D012121:Respiration, Artificial / Q000009:adverse effects* / Q000379:methods*; D012890:Sleep