Awake prone positioning (APP) reduces the intubation rate in COVID-19 patients treated by high-flow nasal cannula (HFNC). However, the lung aeration response to APP has not been addressed. We aimed to explore the lung aeration response to APP by lung ultrasound (LUS). This two-center, prospective, observational study enrolled patients with COVID-19-induced acute hypoxemic respiratory failure treated by HFNC and APP. LUS score was recorded 5–10 min before, 1 h after APP, and 5–10 min after supine in the first APP session within the first three days. The primary outcome was LUS score changes in the first three days. Secondary outcomes included changes in SpO2/FiO2 ratio, respiratory rate and ROX index (SpO2/FiO2/respiratory rate) related to APP, and the rate of treatment success (patients who avoided intubation). Seventy-one patients were enrolled. LUS score decreased from 20 (interquartile range [IQR] 19–24) to 19 (18–21) (p < 0.001) after the first APP session, and to 19 (18–21) (p < 0.001) after three days. Compared to patients with treatment failure (n = 20, 28%), LUS score reduction after the first three days in patients with treatment success (n = 51) was greater (− 2.6 [95% confidence intervals − 3.1 to − 2.0] vs 0 [− 1.2 to 1.2], p = 0.001). A decrease in dorsal LUS score > 1 after the first APP session was associated with decreased risk for intubation (Relative risk 0.25 [0.09–0.69]). APP daily duration was correlated with LUS score reduction in patients with treatment success, especially in dorsal lung zones (r = − 0.76; p < 0.001). In patients with acute hypoxemic respiratory failure due to COVID-19 and treated by HFNC, APP reduced LUS score. The reduction in dorsal LUS scores after APP was associated with treatment success. The longer duration on APP was correlated with greater lung aeration. Trial registration This study was prospectively registered on clinicaltrials.gov on April 22, 2021. Identification number NCT04855162 .

中文翻译：

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肺超声对清醒俯卧位的反应预测 COVID-19 引起的急性低氧性呼吸衰竭患者需要插管：一项观察性研究

清醒俯卧位 (APP) 可降低接受高流量鼻导管 (HFNC) 治疗的 COVID-19 患者的插管率。然而，肺通气对 APP 的反应尚未得到解决。我们旨在通过肺部超声 (LUS) 探索肺通气对 APP 的反应。这项双中心、前瞻性、观察性研究招募了接受 HFNC 和 APP 治疗的 COVID-19 引起的急性低氧性呼吸衰竭患者。在前三天的第一个 APP 会话中，在 APP 前 5-10 分钟、APP 后 1 小时和仰卧后 5-10 分钟记录 LUS 评分。主要结果是前三天的 LUS 评分变化。次要结局包括与 APP 相关的 SpO2/FiO2 比值、呼吸频率和 ROX 指数（SpO2/FiO2/呼吸频率）的变化，以及治疗成功率（避免插管的患者）。招募了 71 名患者。LUS 评分在第一次 APP 会话后从 20（四分位距 [IQR] 19-24）降至 19（18-21）（p < 0.001），三天后降至 19（18-21）（p < 0.001）。与治疗失败的患者（n = 20, 28%）相比，治疗成功的患者（n = 51）在前三天后的 LUS 评分下降幅度更大（- 2.6 [95% 置信区间 - 3.1 到 - 2.0] 与0 [− 1.2 到 1.2]，p = 0.001)。第一次 APP 会话后背侧 LUS 评分降低 > 1 与插管风险降低相关（相对风险 0.25 [0.09-0.69]）。APP 每日持续时间与治疗成功患者的 LUS 评分降低相关，尤其是在肺背区（r = - 0.76；p < 0.001）。在因 COVID-19 导致急性低氧性呼吸衰竭并接受 HFNC 治疗的患者中，APP 降低了 LUS 评分。APP 后背侧 LUS 评分的降低与治疗成功有关。APP 使用时间越长，肺通气量越大。试验注册 本研究于 2021 年 4 月 22 日在临床试验网站上进行了前瞻性注册。识别号 NCT04855162。