Adult Intensive Care Unit, Lausanne University Hospital, Lausanne, Switzerland.
Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
Respir Res. 2022 Nov 19;23(1):320. doi: 10.1186/s12931-022-02247-8.
COVID-19 related acute respiratory distress syndrome (ARDS) has specific characteristics compared to ARDS in other populations. Proning is recommended by analogy with other forms of ARDS, but few data are available regarding its physiological effects in this population. This study aimed to assess the effects of proning on oxygenation parameters (PaO/FiO and alveolo-arterial gradient (Aa-gradient)), blood gas analysis, ventilatory ratio (VR), respiratory system compliance (C) and estimated dead space fraction (V/V HB). We also looked for variables associated with treatment failure.
Retrospective monocentric study of intubated COVID-19 ARDS patients managed with an early intubation, low to moderate positive end-expiratory pressure and early proning strategy hospitalized from March 6 to April 30 2020. Blood gas analysis, PaO/FiO, Aa-gradient, VR, C and V/V HB were compared before and at the end of each proning session with paired t-tests or Wilcoxon tests (p < 0.05 considered as significant). Proportions were assessed using Fischer exact test or Chi square test.
Forty-two patients were included for a total of 191 proning sessions, median duration of 16 (5-36) hours. Considering all sessions, PaO/FiO increased (180 [148-210] vs 107 [90-129] mmHg, p < 0.001) and Aa-gradient decreased (127 [92-176] vs 275 [211-334] mmHg, p < 0.001) with proning. C (36.2 [30.0-41.8] vs 32.2 [27.5-40.9] ml/cmHO, p = 0.003), VR (2.4 [2.0-2.9] vs 2.3 [1.9-2.8], p = 0.028) and V/V HB (0.72 [0.67-0.76] vs 0.71 [0.65-0.76], p = 0.022) slightly increased. Considering the first proning session, PaO/FiO increased (186 [165-215] vs 104 [94-126] mmHg, p < 0.001) and Aa-gradient decreased (121 [89-160] vs 276 [238-321] mmHg, p < 0.001), while C, VR and V/V HB were unchanged. Similar variations were observed during the subsequent proning sessions. Among the patients who experienced treatment failure (defined as ICU death or need for extracorporeal membrane oxygenation), fewer expressed a positive response in terms of oxygenation (defined as increase of more than 20% in PaO/FiO) to the first proning (67 vs 97%, p = 0.020).
Proning in COVID-19 ARDS intubated patients led to an increase in PaO/FiO and a decrease in Aa-gradient if we consider all the sessions together, the first one or the 4 subsequent sessions independently. When considering all sessions, C increased and VR and V/V HB only slightly increased.
与其他人群的 ARDS 相比，COVID-19 相关的急性呼吸窘迫综合征（ARDS）具有特定的特征。与其他形式的 ARDS 类似，建议采用俯卧位，但关于该人群的生理效应，目前仅有少量数据。本研究旨在评估俯卧位对氧合参数（PaO/FiO 和肺泡-动脉梯度（Aa-gradient））、血气分析、通气比（VR）、呼吸系统顺应性（C）和估计的死腔分数（V/V HB）的影响。我们还寻找了与治疗失败相关的变量。
这是一项回顾性的单中心研究，纳入了 2020 年 3 月 6 日至 4 月 30 日期间因 COVID-19 导致 ARDS 而接受早期插管、低至中水平呼气末正压通气和早期俯卧位策略治疗的插管 COVID-19 ARDS 患者。采用配对 t 检验或 Wilcoxon 检验比较每一次俯卧位治疗前后的血气分析、PaO/FiO、Aa-gradient、VR、C 和 V/V HB（p<0.05 为差异有统计学意义）。采用 Fischer 精确检验或卡方检验评估比例。
共纳入 42 例患者，共计 191 次俯卧位治疗，中位时间为 16（5-36）小时。考虑所有的治疗，俯卧位后 PaO/FiO 增加（180[148-210]比 107[90-129]mmHg，p<0.001），Aa-gradient 降低（127[92-176]比 275[211-334]mmHg，p<0.001）。C（36.2[30.0-41.8]比 32.2[27.5-40.9]ml/cmHO，p=0.003）、VR（2.4[2.0-2.9]比 2.3[1.9-2.8]，p=0.028）和 V/V HB（0.72[0.67-0.76]比 0.71[0.65-0.76]，p=0.022）略有增加。考虑第一次俯卧位治疗，PaO/FiO 增加（186[165-215]比 104[94-126]mmHg，p<0.001），Aa-gradient 降低（121[89-160]比 276[238-321]mmHg，p<0.001），而 C、VR 和 V/V HB 没有变化。在随后的俯卧位治疗中也观察到类似的变化。在经历治疗失败（定义为 ICU 死亡或需要体外膜氧合）的患者中，第一次俯卧位治疗时，氧合改善（定义为 PaO/FiO 增加超过 20%）的患者比例较少（67%比 97%，p=0.020）。
在 COVID-19 导致的 ARDS 插管患者中，如果考虑所有的治疗，第一次治疗或随后的 4 次治疗，俯卧位治疗可导致 PaO/FiO 增加，Aa-gradient 降低。如果考虑所有的治疗，C 增加，VR 和 V/V HB 仅略有增加。
