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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急性呼吸窘迫综合征患者床位垂直化的生理效应和安全性


急性呼吸窘迫综合征 （ARDS） 患者仰卧位的躯干倾斜因其对呼吸生理学的影响而引起了科学兴趣，包括力学、氧合、通气分配和效率。由于呼吸系统顺应性降低，从平躺位变为半卧位会增加驾驶压力。位置调整也会降低去除 CO2 的通气效率，尤其是在 COVID-19 相关 ARDS （C-ARDS） 中，表明可能存在肺实质过度膨胀。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力，从而显着影响血流动力学和气体交换。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。该方案涉及从 30° 半坐姿（基线）到 30° 不同级别的倾斜度（0°、30°、60° 和 90°）的 30 分钟步进逐渐垂直化，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。主要终点是通过垂直手术的跨肺驱动压力的变化。从 2020 年 5 月到 2021 年 1 月，共纳入 30 名患者。从基线（中位和四分位距 [IQR]，9 [5-11] cmH2O）到 90° 位置（10 [7-14] cmH2O;P < 10-2 为混合模型中位置的总体效应）。呼气末肺容积随着垂直化而增加，同时肺泡应变的减少和动脉氧合的增加。 垂直化与心输出量和每搏输出量减少、去甲肾上腺素剂量和血清乳酸水平增加相关，促使 2 例患者中断手术。没有其他不良事件，例如跌倒或设备意外移除。垂直至 90° 在 ARDS 患者中是可行的，可将 EELV 和氧合改善至 30°，这可能是由于肺泡募集和血流再分布。然而，超过 30° 存在过度膨胀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床角。试用注册 ClinicalTrials.gov 注册号 NCT04371016,2020 年 4 月 24 日。