Driving Pressure Is Associated with Outcome during Assisted Ventilation in Acute Respiratory Distress Syndrome

Abstract

Abstract Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New Background Driving pressure, the difference between plateau pressure and positive end-expiratory pressure (PEEP), is closely associated with increased mortality in patients with acute respiratory distress syndrome (ARDS). Although this relationship has been demonstrated during controlled mechanical ventilation, plateau pressure is often not measured during spontaneous breathing because of concerns about validity. The objective of the present study is to verify whether driving pressure and respiratory system compliance are independently associated with increased mortality during assisted ventilation (i.e., pressure support ventilation). Methods This is a retrospective cohort study conducted on 154 patients with ARDS in whom plateau pressure during the first three days of assisted ventilation was available. Associations between driving pressure, respiratory system compliance, and survival were assessed by univariable and multivariable analysis. In patients who underwent a computed tomography scan (n = 23) during the stage of assisted ventilation, the quantity of aerated lung was compared with respiratory system compliance measured on the same date. Results In contrast to controlled mechanical ventilation, plateau pressure during assisted ventilation was higher than the sum of PEEP and pressure support (peak pressure). Driving pressure was higher (11 [9–14] vs. 10 [8–11] cm H2O; P = 0.004); compliance was lower (40 [30–50] vs. 51 [42–61] ml · cm H2O-1; P < 0.001); and peak pressure was similar, in nonsurvivors versus survivors. Lower respiratory system compliance (odds ratio, 0.92 [0.88–0.96]) and higher driving pressure (odds ratio, 1.34 [1.12–1.61]) were each independently associated with increased risk of death. Respiratory system compliance was correlated with the aerated lung volume (n = 23, r = 0.69, P < 0.0001). Conclusions In patients with ARDS, plateau pressure, driving pressure, and respiratory system compliance can be measured during assisted ventilation, and both higher driving pressure and lower compliance are associated with increased mortality.