Division of Respiratory and Critical Care Medicine, Department of Internal Medicine, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Republic of Korea.
Division of Allergy and Pulmonology, Department of Internal Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, Republic of Korea.
PLoS One. 2022 May 12;17(5):e0268431. doi: 10.1371/journal.pone.0268431. eCollection 2022.
The ratio of oxygen saturation (ROX) index, defined as the ratio of oxygen saturation (SpO2)/fraction of inspired oxygen (FiO2) to respiratory rate, can help identify patients with hypoxemic respiratory failure at high risk for intubation following high-flow nasal cannula (HFNC) initiation; however, whether it is effective for predicting intubation in coronavirus disease 2019 (COVID-19) patients receiving HFNC remains unknown. Moreover, the SpO2/FiO2 ratio has been assessed as a prognostic marker for acute hypoxemic respiratory failure. This study aimed to determine the utility of the ROX index and the SpO2/FiO2 ratio as predictors of failure in COVID-19 patients who received HFNC.
This multicenter study was conducted in seven university-affiliated hospitals in Korea. Data of consecutive hospitalized patients diagnosed with COVID-19 between February 10, 2020 and February 28, 2021 were retrospectively reviewed. We calculated the ROX index and the SpO2/FiO2 ratio at 1 h, 4 h, and 12 h after HFNC initiation. The primary outcome was HFNC failure defined as the need for subsequent intubation despite HFNC application. The receiver operating characteristic curve analysis was used to evaluate discrimination of prediction models for HFNC failure.
Of 1,565 hospitalized COVID-19 patients, 133 who received HFNC were analyzed. Among them, 63 patients (47.4%) were successfully weaned from HFNC, and 70 (52.6%) were intubated. Among patients with HFNC failure, 32 (45.7%) died. The SpO2/FiO2 ratio at 1 h after HFNC initiation was an important predictor of HFNC failure (AUC 0.762 [0.679-0.846]). The AUCs of SpO2/FiO2 ratio at 4 h and ROX indices at 1 h and 4 h were 0.733 (0.640-0.826), 0.697 (0.597-0.798), and 0.682 (0.583-0.781), respectively. Multivariable analysis showed that the patients aged ≥70 years are 3.4 times more likely to experience HFNC failure than those aged <70 years (HR 3.367 [1.358-8.349], p = 0.009). The SpO2/FiO2 ratio (HR 0.983 [0.972-0.994], p = 0.003) at 1 h was significantly associated with HFNC failure.
The SpO2/FiO2 ratio following HFNC initiation was an acceptable predictor of HFNC failure. The SpO2/FiO2 ratio may be a good prognostic marker for predicting intubation in COVID-9 patients receiving HFNC.
氧饱和度指数（ROX 指数）定义为氧饱和度（SpO2）/吸入氧分数（FiO2）与呼吸率的比值，可帮助识别接受高流量鼻导管（HFNC）治疗后有发生低氧性呼吸衰竭高风险需要插管的患者；然而，它是否可有效预测接受 HFNC 治疗的 2019 年冠状病毒病（COVID-19）患者插管仍然未知。此外，SpO2/FiO2 比值已被评估为急性低氧性呼吸衰竭的预后标志物。本研究旨在确定 ROX 指数和 SpO2/FiO2 比值作为预测 COVID-19 患者 HFNC 治疗失败的指标。
这是一项在韩国 7 所大学附属医院进行的多中心研究。回顾性分析了 2020 年 2 月 10 日至 2021 年 2 月 28 日期间连续住院的 COVID-19 确诊患者的数据。我们在 HFNC 启动后 1 小时、4 小时和 12 小时计算 ROX 指数和 SpO2/FiO2 比值。主要结局为 HFNC 治疗失败，定义为尽管应用 HFNC 但仍需要后续插管。使用受试者工作特征曲线分析评估预测 HFNC 治疗失败的模型的区分度。
在 1565 名住院 COVID-19 患者中，分析了 133 名接受 HFNC 的患者。其中，63 名（47.4%）患者成功脱离 HFNC，70 名（52.6%）患者插管。HFNC 治疗失败的患者中，有 32 名（45.7%）死亡。HFNC 启动后 1 小时的 SpO2/FiO2 比值是 HFNC 治疗失败的重要预测指标（AUC 0.762 [0.679-0.846]）。HFNC 启动后 4 小时 SpO2/FiO2 比值和 1 小时、4 小时 ROX 指数的 AUC 分别为 0.733（0.640-0.826）、0.697（0.597-0.798）和 0.682（0.583-0.781）。多变量分析显示，≥70 岁的患者发生 HFNC 治疗失败的可能性是<70 岁患者的 3.4 倍（HR 3.367 [1.358-8.349]，p=0.009）。HFNC 启动后 1 小时的 SpO2/FiO2 比值（HR 0.983 [0.972-0.994]，p=0.003）与 HFNC 治疗失败显著相关。
HFNC 启动后 SpO2/FiO2 比值是 HFNC 治疗失败的可接受预测指标。HFNC 治疗失败后，SpO2/FiO2 比值可能是预测 COVID-19 患者接受 HFNC 治疗时需要插管的良好预后标志物。
