• 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 physiologic effects of different ventilation strategies on patients with ARDS need to be better understood.Research QuestionIn patients with ARDS receiving controlled mandatory ventilation, does airway pressure release ventilation (APRV) improve lung ventilation/perfusion (V˙/Q˙) matching and ventilation homogeneity compared with low tidal volume (LTV) ventilation?Study Design And MethodsThis study was a single-center randomized controlled trial. Patients with moderate to severe ARDS were ventilated randomly with APRV or LTV ventilation. Electrical impedance tomography (EIT) was used to assess lung ventilation and perfusion. EIT-based data and clinical variables related to respiratory and hemodynamic conditions were collected shortly before randomization (0 hours) and at 12 and 24 hours after randomization.ResultsA total of 40 patients were included and randomized to the APRV or LTV ventilation group (20 per group). During the 24-hour trial period, patients receiving APRV exhibited significantly increased dorsal ventilation (difference value [24 hours minus 0 hours]: median, 10.82% [interquartile range (IQR), 2.62%-13.74%] vs 0.12% [IQR, -2.81% to 4.76%]; P = .017), decreased dorsal shunt (median, -4.67% [IQR, -6.83% to 0.59%] vs 1.73% [IQR, -0.95% to 5.53%]; P = .008), and increased dorsal V˙/Q˙ matching (median, 4.13% [IQR, -0.26% to 10.47%] vs -3.29% [IQR, -5.05% to 2.81%]; P = .026) than those receiving LTV ventilation. No difference in ventral dead space was observed between study groups (P = .903). Additionally, two indicators of ventilation distribution heterogeneity, global inhomogeneity index and center of ventilation, significantly decreased and significantly increased, respectively, in the APRV group compared with the LTV ventilation group. Patients receiving APRV showed significantly higher Pao2 to Fio2 ratio, higher respiratory system static compliance and lower Paco2 than those receiving LTV ventilation at 24 hours. The cardiac output was comparable in both groups.InterpretationAPRV, as compared with LTV ventilation, could recruit dorsal region, reduce dorsal shunt, increase dorsal V˙/Q˙ matching, and improve ventilation homogeneity of the lungs, leading to better gas exchange and respiratory system static compliance in patients with moderate to severe ARDS.Clinical Trial RegistryClinicalTrials.gov; No.: NCT05767125; URL: www.Clinicaltrialsgov.Copyright © 2024 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

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