Airway pressure release ventilation as a primary ventilatory mode in acute respiratory distress syndrome.
BACKGROUND
Airway pressure release ventilation (APRV) is a ventilatory mode, which allows unsupported spontaneous breathing at any phase of the ventilatory cycle. Airway pressure release ventilation as compared with pressure support (PS), another partial ventilatory mode, has been shown to improve gas exchange and cardiac output. We hypothesized whether the use of APRV with maintained unsupported spontaneous breathing as an initial mode of ventilatory support promotes faster recovery from respiratory failure in patients with acute respiratory distress syndrome (ARDS) than PS combined with synchronized intermittent ventilation (SIMV-group).


METHODS
In a randomized trial 58 patients were randomized to receive either APRV or SIMV after a predefined stabilization period. Both groups shared common physiological targets, and uniform principles of general care were followed.


RESULTS
Inspiratory pressure was significantly lower in the APRV-group (25.9 +/- 0.6 vs. 28.6 +/- 0.7 cmH2O) within the first week of the study (P = 0.007). PEEP-levels and physiological variables (PaO2/FiO2-ratio, PaCO2, pH, minute ventilation, mean arterial pressure, cardiac output) were comparable between the groups. At day 28, the number of ventilator-free days was similar (13.4 +/- 1.7 in the APRV-group and 12.2 +/- 1.5 in the SIMV-group), as was the mortality (17% and 18%, respectively).


CONCLUSIONS
We conclude that when used as a primary ventilatory mode in patients with ARDS, APRV did not differ from SIMV with PS in clinically relevant outcome.
Varpula
T
T
Department of Anesthesiology and Intensive Care Medicine, Jorvi Hospital, Helsinki University Hospital, Espoo, Finland. tero.varpula@hus.fi
Valta
P
P
Niemi
R
R
Takkunen
O
O
Hynynen
M
M
Pettilä
V V
VV
D000328:Adult; D018686:Anesthetics, Intravenous / Q000627:therapeutic use; D001794:Blood Pressure / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D045422:Continuous Positive Airway Pressure / Q000379:methods*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005283:Fentanyl / Q000627:therapeutic use; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007385:Intermittent Positive-Pressure Ventilation / Q000379:methods; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D015742:Propofol / Q000627:therapeutic use; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012128:Respiratory Distress Syndrome / Q000628:therapy*; D015656:Respiratory Mechanics / Q000502:physiology; D018709:Statistics, Nonparametric; D013997:Time Factors; D016896:Treatment Outcome
D018686:Anesthetics, Intravenous; D010100:Oxygen; D005283:Fentanyl; D015742:Propofol