Trunk inclination in patients with Acute Respiratory Distress Syndrome (ARDS) in the supine position has gained scientific interest due to its effects on respiratory physiology, including mechanics, oxygenation, ventilation distribution, and efficiency. Changing from flat supine to semi-recumbent increases driving pressure due to decreased respiratory system compliance. Positional adjustments also deteriorate ventilatory efficiency for CO2 removal, particularly in COVID-19-associated ARDS (C-ARDS), indicating likely lung parenchyma overdistension. Tilting the trunk reduces chest wall compliance and, to a lesser extent, lung compliance and transpulmonary driving pressure, with significant hemodynamic and gas exchange implications. A prospective, pilot physiological study was conducted on early ARDS patients in two ICUs at CHU Clermont-Ferrand, France. The protocol involved 30-min step gradual verticalization from a 30° semi-seated position (baseline) to different levels of inclination (0°, 30°, 60°, and 90°), before returning to the baseline position. Measurements included tidal volume, positive end-expiratory pressure (PEEP), esophageal pressures, and pulmonary artery catheter data. The primary endpoint was the variation in transpulmonary driving pressure through the verticalization procedure. From May 2020 through January 2021, 30 patients were included. Transpulmonary driving pressure increased slightly from baseline (median and interquartile range [IQR], 9 [5–11] cmH2O) to the 90° position (10 [7–14] cmH2O; P < 10–2 for the overall effect of position in mixed model). End-expiratory lung volume increased with verticalization, in parallel to decreases in alveolar strain and increased arterial oxygenation. Verticalization was associated with decreased cardiac output and stroke volume, and increased norepinephrine doses and serum lactate levels, prompting interruption of the procedure in two patients. There were no other adverse events such as falls or equipment accidental removals. Verticalization to 90° is feasible in ARDS patients, improving EELV and oxygenation up to 30°, likely due to alveolar recruitment and blood flow redistribution. However, there is a risk of overdistension and hemodynamic instability beyond 30°, necessitating individualized bed angles based on clinical situations. Trial registration ClinicalTrials.gov registration number NCT04371016 , April 24, 2020.

中文翻译：

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床垂直化对急性呼吸窘迫综合征患者的生理影响和安全性


急性呼吸窘迫综合征 (ARDS) 患者仰卧时的躯干倾斜度因其对呼吸生理学（包括力学、氧合、通气分布和效率）的影响而引起了科学界的兴趣。由于呼吸系统顺应性降低，从平卧位改为半卧位会增加驱动压力。位置调整还会降低二氧化碳清除的通气效率，特别是在与 COVID-19 相关的 ARDS (C-ARDS) 中，这表明肺实质可能过度扩张。倾斜躯干会降低胸壁顺应性，并在较小程度上降低肺顺应性和跨肺驱动压，从而对血流动力学和气体交换产生显着影响。在法国 CHU Clermont-Ferrand 的两个 ICU 中对早期 ARDS 患者进行了一项前瞻性、试点生理学研究。该协议涉及从 30° 半坐位（基线）到不同倾斜度（0°、30°、60° 和 90°）的 30 分钟逐步垂直化，然后返回到基线位置。测量包括潮气量、呼气末正压 (PEEP)、食管压和肺动脉导管数据。主要终点是垂直化过程中跨肺驱动压的变化。从2020年5月到2021年1月，共纳入了30名患者。跨肺驱动压从基线（中位和四分位距 [IQR]，9 [5–11] cmH2O）略微增加到 90° 位置（10 [7–14] cmH2O；对于位置的总体影响，P < 10–2在混合模型中）。呼气末肺容积随着垂直化而增加，同时肺泡应变减少和动脉氧合增加。 垂直化与心输出量和每搏输出量减少以及去甲肾上腺素剂量和血清乳酸水平增加相关，导致两名患者的手术中断。没有发生跌倒或设备意外移动等其他不良事件。对于 ARDS 患者，垂直至 90° 是可行的，可将 EELV 和氧合改善高达 30°，这可能是由于肺泡复张和血流重新分布。然而，超过 30° 存在过度扩张和血流动力学不稳定的风险，需要根据临床情况进行个体化的床角度。试验注册 ClinicalTrials.gov 注册号 NCT04371016，2020 年 4 月 24 日。