Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada.
Department of Medicine, Division of Respirology, University Health Network/Sinai Health System, University of Toronto, Toronto, Canada.
Crit Care. 2023 Apr 13;27(1):140. doi: 10.1186/s13054-023-04428-3.
Prone positioning is an evidence-based treatment for patients with moderate-to-severe acute respiratory distress syndrome. Lung recruitment has been proposed as one of the mechanisms by which prone positioning reduces mortality in this group of patients. Recruitment-to-inflation ratio (R/I) is a method to measure potential for lung recruitment induced by a change in positive end-expiratory pressure (PEEP) on the ventilator. The association between R/I and potential for lung recruitment in supine and prone position has not been studied with computed tomography (CT) scan imaging. In this secondary analysis, we sought to investigate the correlation between R/I measured in supine and prone position with CT and the potential for lung recruitment as measured by CT scan. Among 23 patients, the median R/I did not significantly change from supine (1.9 IQR 1.6-2.6) to prone position (1.7 IQR 1.3-2.8) (paired t test p = 0.051) but the individual changes correlated with the different response to PEEP. In supine and in prone position, R/I significantly correlated with the proportion of lung tissue recruitment induced by the change of PEEP. Lung tissue recruitment induced by a change of PEEP from 5 to 15 cmHO was 16% (IQR 11-24%) in supine and 14.3% (IQR 8.4-22.6%) in prone position, as measured by CT scan analysis (paired t test p = 0.56). In this analysis, PEEP-induced recruitability as measured by R/I correlated with PEEP-induced lung recruitment as measured by CT scan, and could help to readjust PEEP in prone position.
俯卧位是治疗中重度急性呼吸窘迫综合征患者的一种基于证据的治疗方法。肺复张被认为是俯卧位降低该组患者死亡率的机制之一。复张-膨胀比（R/I）是一种测量呼吸机呼气末正压（PEEP）变化诱导肺复张潜力的方法。仰卧位和俯卧位时 R/I 与肺复张潜力之间的关系尚未通过 CT 扫描成像进行研究。在这项二次分析中，我们试图研究仰卧位和俯卧位时 R/I 与 CT 之间的相关性，以及 CT 测量的肺复张潜力。在 23 名患者中，从仰卧位（1.9 IQR 1.6-2.6）到俯卧位（1.7 IQR 1.3-2.8），R/I 中位数没有显著变化（配对 t 检验，p=0.051），但个体变化与对 PEEP 的不同反应相关。在仰卧位和俯卧位，R/I 与 PEEP 变化诱导的肺组织复张比例显著相关。PEEP 从 5 厘米水柱增加到 15 厘米水柱时，仰卧位和俯卧位时肺组织复张的比例分别为 16%（IQR 11%-24%）和 14.3%（IQR 8.4%-22.6%），这是通过 CT 扫描分析得出的（配对 t 检验，p=0.56）。在这项分析中，R/I 测量的 PEEP 诱导可复张性与 CT 扫描测量的 PEEP 诱导肺复张性相关，并且可以帮助调整俯卧位时的 PEEP。
