• Hongling Zhang, Yongran Wu, Ruiting Li, Xuehui Gao, Azhen Wang, Xin Zhao, Xiaobo Yang, Huaqing Shu, Hong Qi, Zhaohui Fu, Shiying Yuan, Yilei Ma, Le Yang, Xiaojing Zou, You Shang, and Zhanqi Zhao.
• Department of Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
• Chest. 2024 Sep 17.

BackgroundThe physiological effects of different ventilation strategies on patients with acute respiratory distress syndrome (ARDS) need to be better understood.Research QuestionIn patients with ARDS under controlled mandatory ventilation, does airway pressure release ventilation (APRV) improve lung ventilation-perfusion matching and ventilation homogeneity compared to low tidal volume ventilation (LTV)?Study Design And MethodsThis study was a single-center randomized controlled trial. Patients with moderate-to-severe ARDS were randomly ventilated on APRV or LTV. Electrical impedance tomography (EIT) was utilized to assess lung ventilation and perfusion. EIT-based data and clinical variables related to respiratory and hemodynamic conditions were collected shortly before randomization (0h), and at 12 and 24 hours after randomization.ResultsA total of 40 subjects were included and randomized to the APRV or LTV group (20 per group). During the 24-hour trial period, patients on APRV exhibited significantly increased dorsal ventilation (difference value (24h-0h), median [25-75 percentiles]: 10.82% [2.62-13.74] vs 0.12% [-2.81-4.76], P = .017), decreased dorsal shunt (-4.67% [-6.83-0.59] vs 1.73% [-0.95-5.53], P = .008) and increased dorsal ventilation-perfusion matching (4.13% [-0.26-10.47] vs -3.29% [-5.05-2.81], P = .026) than those on LTV; no difference in ventral dead space was observed between study groups (P = .903). Additionally, two indicators of ventilation distribution heterogeneity: global inhomogeneity index significantly decreased, and center of ventilation significantly increased in the APRV group compared to the LTV group. Patients on APRV had significantly higher PaO2/FiO2, higher respiratory system static compliance (Crs) and lower PaCO2 than those on LTV at 24h. The cardiac output was comparable in both groups.InterpretationAPRV, as compared to LTV, could recruit dorsal region, reduce dorsal shunt, increase dorsal ventilation-perfusion matching, and improve ventilation homogeneity of the lungs, leading to better gas exchange and Crs in patients with moderate-to-severe ARDS.Copyright © 2024. Published by Elsevier Inc.

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