Chang, Ko-WeiKo-WeiChangLeu, Shaw-WoeiShaw-WoeiLeuHu, Han-ChungHan-ChungHuChan, Ming-ChengMing-ChengChanLiang, Shinn-JyeShinn-JyeLiangYang, Kuang-YaoKuang-YaoYangFang, Wen-FengWen-FengFangSheu, Chau-ChyunChau-ChyunSheuYING-CHUN CHIENPeng, Chung-KanChung-KanPengHuang, Ching-TzuChing-TzuHuangKao, Kuo-ChinKuo-ChinKao2025-07-092025-07-092025-06-12https://scholars.lib.ntu.edu.tw/handle/123456789/730634Background: Prone positioning has demonstrated decreased mortality in moderate to severe acute respiratory distress syndrome (ARDS) patients. This study aimed to investigate the gas exchange effect of prone positioning in moderate to severe ARDS patients. Methods: This retrospective study includes eight tertiary referral centers. Demographic data, laboratory data, treatment records, ventilator setting data, and outcomes were collected. Arterial blood gas data were collected before and 24 h after the initiation of prone positioning and under the supine position. PaO2 responders were defined as the PaO2/FiO2 ratio increasing by ≥ 20 % or ≥20 mm Hg, while PaCO2 responders were defined as PaCO2 decreasing by ≥ 1 mm Hg after prone positioning for one day. Results: One hundred thirty-eight patients receiving prone positioning were enrolled, with 86 (62.3 %) being PaO2 responders and 67 (48.6 %) being PaCO2 responders. Mortality rates were not significantly different between PaO2 responders and non-responders at day 28 (29.1 % vs. 38.5 %, P = 0.254) or day 60 (39.5 % vs. 50.0 %, P = 0.229). PaCO2 responders had a significantly lower mortality rate at day 28 (20.9 % vs. 43.7 %, P = 0.004) and day 60 (31.3 % vs. 54.9 %, P = 0.005). The PaCO2 responders had significant improvement in minute ventilation (10.2 ± 2.5 vs. 10.9 ± 2.8 L/min, P = 0.024), dynamic driving pressure (18.7 ± 4.1 vs. 17.6 ± 4.0 cmH2O, P = 0.004), and lung compliance [21.4(17.8–27.6) vs. 23.5(19.9–29.0) L/cmH2O, P = 0.002] after prone positioning. Conclusions: In this multicenter retrospective cohort study of patients with ARDS receiving prone positioning, PaCO2 responders had better clinical outcomes than PaCO2 non-responders.enAcute respiratory distress syndromeGas exchangeInfluenzaOutcomeProne positioningjournal article10.1016/j.jfma.2025.06.02040514296