Recent reports of patients with severe, late-stage COVID-19 ARDS with reduced respiratory system compliance described paradoxical decreases in plateau pressure and increases in respiratory system compliance in response to anterior chest wall loading. We aimed to assess the effect of chest wall loading during supine and prone position in ill patients with COVID-19-related ARDS and to investigate the effect of a low or normal baseline respiratory system compliance on the findings. This is a single-center, prospective, cohort study in the intensive care unit of a COVID-19 referral center. Consecutive mechanically ventilated, critically ill patients with COVID-19-related ARDS were enrolled and classified as higher (≥ 40 ml/cmH2O) or lower respiratory system compliance (< 40 ml/cmH2O). The study included four steps, each lasting 6 h: Step 1, supine position, Step 2, 10-kg continuous chest wall compression (supine + weight), Step 3, prone position, Step 4, 10-kg continuous chest wall compression (prone + weight). The mechanical properties of the respiratory system, gas exchange and alveolar dead space were measured at the end of each step. Totally, 40 patients were enrolled. In the whole cohort, neither oxygenation nor respiratory system compliance changed between supine and supine + weight; both increased during prone positioning and were unaffected by chest wall loading in the prone position. Alveolar dead space was unchanged during all the steps. In 16 patients with reduced compliance, PaO2/FiO2 significantly increased from supine to supine + weight and further with prone and prone + weight (107 ± 15.4 vs. 120 ± 18.5 vs. 146 ± 27.0 vs. 159 ± 30.4, respectively; p < 0.001); alveolar dead space decreased from both supine and prone position after chest wall loading, and respiratory system compliance significantly increased from supine to supine + weight and from prone to prone + weight (23.9 ± 3.5 vs. 30.9 ± 5.7 and 31.1 ± 5.7 vs. 37.8 ± 8.7 ml/cmH2O, p < 0.001). The improvement was higher the lower the baseline compliance. Unlike prone positioning, chest wall loading had no effects on respiratory system compliance, gas exchange or alveolar dead space in an unselected cohort of critically ill patients with C-ARDS. Only patients with a low respiratory system compliance experienced an improvement, with a higher response the lower the baseline compliance.

中文翻译：

---

COVID-19 ARDS 患者仰卧位和俯卧位时的胸壁负荷：对呼吸力学和气体交换的影响

最近关于呼吸系统顺应性降低的严重晚期 COVID-19 ARDS 患者的报告描述了平台压的反常降低和呼吸系统顺应性随着前胸壁负荷的增加而增加。我们旨在评估 COVID-19 相关 ARDS 患者在仰卧位和俯卧位时胸壁负荷的影响，并研究低或正常基线呼吸系统顺应性对结果的影响。这是一项在 COVID-19 转诊中心的重症监护病房进行的单中心、前瞻性、队列研究。连续机械通气的重症 COVID-19 相关 ARDS 患者被纳入研究，并将其分类为较高 (≥ 40 ml/cmH2O) 或较低的呼吸系统顺应性 (< 40 ml/cmH2O)。该研究包括四个步骤，每个步骤持续 6 小时： 步骤 1，仰卧位，第 2 步，10 公斤连续胸壁按压（仰卧 + 负重），第 3 步，俯卧位，第 4 步，10 公斤连续胸壁按压（俯卧 + 负重）。在每个步骤结束时测量呼吸系统、气体交换和肺泡死腔的机械性能。共招募了40名患者。在整个队列中，仰卧位和仰卧位+体重之间的氧合和呼吸系统顺应性均未发生变化；俯卧位时两者均增加，并且不受俯卧位胸壁负荷的影响。肺泡死腔在所有步骤中均未发生变化。在 16 名顺应性降低的患者中，PaO2/FiO2 从仰卧位显着增加至仰卧位 + 体重，并随着俯卧位和俯卧位 + 体重进一步增加（分别为 107 ± 15.4 vs. 120 ± 18.5 vs. 146 ± 27.0 vs. 159 ± 30.4；p < 0.001); 胸壁负重后，仰卧位和俯卧位肺泡死腔均减少，呼吸系统顺应性从仰卧位到仰卧位+体重以及从俯卧位到俯卧位+体重显着增加（23.9 ± 3.5 vs. 30.9 ± 5.7 和 31.1 ± 5.7 vs. 37.8 ± 8.7 毫升/厘米水柱，p < 0.001)。基线合规性越低，改进越高。与俯卧位不同，在未经选择的 C-ARDS 危重患者队列中，胸壁负荷对呼吸系统顺应性、气体交换或肺泡死腔没有影响。只有呼吸系统顺应性低的患者才会出现改善，反应越高，基线顺应性越低。和呼吸系统顺应性从仰卧位到仰卧位+体重以及从俯卧位到俯卧位+体重显着增加（23.9 ± 3.5 vs. 30.9 ± 5.7 和 31.1 ± 5.7 vs. 37.8 ± 8.7 ml/cmH2O，p < 0.001）。基线合规性越低，改进越高。与俯卧位不同，在未经选择的 C-ARDS 危重患者队列中，胸壁负荷对呼吸系统顺应性、气体交换或肺泡死腔没有影响。只有呼吸系统顺应性低的患者才会出现改善，反应越高，基线顺应性越低。和呼吸系统顺应性从仰卧位到仰卧位+体重以及从俯卧位到俯卧位+体重显着增加（23.9 ± 3.5 vs. 30.9 ± 5.7 和 31.1 ± 5.7 vs. 37.8 ± 8.7 ml/cmH2O，p < 0.001）。基线合规性越低，改进越高。与俯卧位不同，在未经选择的 C-ARDS 危重患者队列中，胸壁负荷对呼吸系统顺应性、气体交换或肺泡死腔没有影响。只有呼吸系统顺应性低的患者才会出现改善，反应越高，基线顺应性越低。在未经选择的 C-ARDS 危重患者队列中，胸壁负荷对呼吸系统顺应性、气体交换或肺泡死腔没有影响。只有呼吸系统顺应性低的患者才会出现改善，反应越高，基线顺应性越低。在未经选择的 C-ARDS 危重患者队列中，胸壁负荷对呼吸系统顺应性、气体交换或肺泡死腔没有影响。只有呼吸系统顺应性低的患者才会出现改善，反应越高，基线顺应性越低。