Inconsistent Methods Used to Set Airway Pressure Release Ventilation in Acute Respiratory Distress Syndrome: A Systematic Review and Meta-Regression Analysis.

Airway pressure release ventilation (APRV) is a protective mechanical ventilation mode for patients with acute respiratory distress syndrome (ARDS) that theoretically may reduce ventilator-induced lung injury (VILI) and ARDS-related mortality. However, there is no standard method to set and adjust the APRV mode shown to be optimal. Therefore, we performed a meta-regression analysis to evaluate how the four individual APRV settings impacted the outcome in these patients. Methods: Studies investigating the use of the APRV mode for ARDS patients were searched from electronic databases. We tested individual settings, including (1) high airway pressure (P High ); (2) low airway pressure (P Low ); (3) time at high airway pressure (T High ); and (4) time at low pressure (T Low ) for association with PaO 2 /FiO 2 ratio and ICU length of stay. Results: There was no significant difference in PaO 2 /FiO 2 ratio between the groups in any of the four settings (P High difference -12.0 [95% CI -100.4, 86.4]; P Low difference 54.3 [95% CI -52.6, 161.1]; T Low difference -27.19 [95% CI -127.0, 72.6]; T High difference -51.4 [95% CI -170.3, 67.5]). There was high heterogeneity across all parameters (P hHgh I 2 = 99.46%, P Low I 2 = 99.16%, T Low I 2 = 99.31%, T High I 2 = 99.29%). Conclusions: None of the four individual APRV settings independently were associated with differences in outcome. A holistic approach, analyzing all settings in combination, may improve APRV efficacy since it is known that small differences in ventilator settings can significantly alter mortality. Future clinical trials should set and adjust APRV based on the best current scientific evidence available.