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Abstract：
In the treatment of acute hypoxemic respiratory failure (AHRF) due to coronavirus 2019 (COVID-19), physicians choose respiratory management ranging from low-flow oxygen therapy to more invasive methods, depending on the severity of the patient\'s symptoms. Recently, the ratio of oxygen saturation (ROX) index has been proposed as a clinical indicator to support the decision for either high-flow nasal cannulation (HFNC) or mechanical ventilation (MV). However, the reported cut-off value of the ROX index ranges widely from 2.7 to 5.9. The objective of this study was to identify indices to achieve empirical physician decisions for MV initiation, providing insights to shorten the delay from HFNC to MV. We retrospectively analyzed the ROX index 6 hours after initiating HFNC and lung infiltration volume (LIV) calculated from chest computed tomography (CT) images in COVID-19 patients with AHRF.
We retrospectively analyzed the data for 59 COVID-19 patients with AHRF in our facility to determine the cut-off value of the ROX index for respiratory therapeutic decisions and the significance of radiological evaluation of pneumonia severity. The physicians chose either HFNC or MV, and the outcomes were retrospectively analyzed using the ROX index for initiating HFNC. LIV was calculated using chest CT images at admission.
Among the 59 patients who required high-flow oxygen therapy with HFNC at admission, 24 were later transitioned to MV; the remaining 35 patients recovered. Four of the 24 patients in the MV group died, and the ROX index values of these patients were 9.8, 7.3, 5.4, and 3.0, respectively. These index values indicated that the ROX index of half of the patients who died was higher than the reported cut-off values of the ROX index, which range from 2.7-5.99. The cut-off value of the ROX index 6 hours after the start of HFNC, which was used to classify the management of HFNC or MV as a physician\'s clinical decision, was approximately 6.1. The LIV cut-off value on chest CT between HFNC and MV was 35.5%. Using both the ROX index and LIV, the cut-off classifying HFNC or MV was obtained using the equation, LIV = 4.26 × (ROX index) + 7.89. The area under the receiver operating characteristic curve, as an evaluation metric of the classification, improved to 0.94 with a sensitivity of 0.79 and specificity of 0.91 using both the ROX index and LIV.
Physicians\' empirical decisions associated with the choice of respiratory therapy for HFNC oxygen therapy or MV can be supported by the combination of the ROX index and the LIV index calculated from chest CT images.
We retrospectively analyzed the data for 59 COVID-19 patients with AHRF in our facility to determine the cut-off value of the ROX index for respiratory therapeutic decisions and the significance of radiological evaluation of pneumonia severity. The physicians chose either HFNC or MV, and the outcomes were retrospectively analyzed using the ROX index for initiating HFNC. LIV was calculated using chest CT images at admission.
Among the 59 patients who required high-flow oxygen therapy with HFNC at admission, 24 were later transitioned to MV; the remaining 35 patients recovered. Four of the 24 patients in the MV group died, and the ROX index values of these patients were 9.8, 7.3, 5.4, and 3.0, respectively. These index values indicated that the ROX index of half of the patients who died was higher than the reported cut-off values of the ROX index, which range from 2.7-5.99. The cut-off value of the ROX index 6 hours after the start of HFNC, which was used to classify the management of HFNC or MV as a physician\'s clinical decision, was approximately 6.1. The LIV cut-off value on chest CT between HFNC and MV was 35.5%. Using both the ROX index and LIV, the cut-off classifying HFNC or MV was obtained using the equation, LIV = 4.26 × (ROX index) + 7.89. The area under the receiver operating characteristic curve, as an evaluation metric of the classification, improved to 0.94 with a sensitivity of 0.79 and specificity of 0.91 using both the ROX index and LIV.
Physicians\' empirical decisions associated with the choice of respiratory therapy for HFNC oxygen therapy or MV can be supported by the combination of the ROX index and the LIV index calculated from chest CT images.
摘要：
■在治疗2019年冠状病毒（COVID-19）引起的急性低氧性呼吸衰竭（AHRF）中，医生选择呼吸管理，从低流量氧疗到更具侵入性的方法，取决于患者症状的严重程度。最近,氧饱和度比率(ROX)指数已被提出作为临床指标,以支持高流量经鼻插管(HFNC)或机械通气(MV)的决策.然而,报告的ROX指数的临界值在2.7~5.9之间.这项研究的目的是确定指标，以实现经验医师决定的MV启动，提供见解，以缩短从HFNC到MV的延迟。我们回顾性分析了COVID-19AHRF患者在开始HFNC后6小时的ROX指数和根据胸部计算机断层扫描（CT）图像计算的肺浸润量（LIV）。
■我们回顾性分析了在我们设施中59例AHRFCOVID-19患者的数据，以确定ROX指数对呼吸系统治疗决策的临界值以及放射学评估肺炎严重程度的意义。医生选择了HFNC或MV，结果采用ROX指数对开始HFNC进行回顾性分析.入院时使用胸部CT图像计算LIV。
■在入院时需要使用HFNC进行高流量氧气治疗的59例患者中，24例后来过渡到MV；其余35例患者康复。MV组24例患者中有4例死亡，这些患者的ROX指数值分别为9.8,7.3,5.4和3.0.这些指标值表明，一半死亡患者的ROX指数高于报告的ROX指数的临界值，范围在2.7-5.99之间。HFNC开始后6小时的ROX指数的截止值，用于将HFNC或MV的管理分类为医师的临床决策，大约是6.1。HFNC和MV在胸部CT上的LIV临界值为35.5％。使用ROX指数和LIV，使用方程获得了对HFNC或MV的截止分类，LIV=4.26×(ROX指数)+7.89。接收器工作特性曲线下的面积，作为分类的评估指标，使用ROX指数和LIV均可提高至0.94,敏感性为0.79,特异性为0.91.
■医师选择HFNC氧疗或MV的呼吸治疗相关的经验决策可以通过从胸部CT图像计算的ROX指数和LIV指数的组合来支持。
■我们回顾性分析了在我们设施中59例AHRFCOVID-19患者的数据，以确定ROX指数对呼吸系统治疗决策的临界值以及放射学评估肺炎严重程度的意义。医生选择了HFNC或MV，结果采用ROX指数对开始HFNC进行回顾性分析.入院时使用胸部CT图像计算LIV。
■在入院时需要使用HFNC进行高流量氧气治疗的59例患者中，24例后来过渡到MV；其余35例患者康复。MV组24例患者中有4例死亡，这些患者的ROX指数值分别为9.8,7.3,5.4和3.0.这些指标值表明，一半死亡患者的ROX指数高于报告的ROX指数的临界值，范围在2.7-5.99之间。HFNC开始后6小时的ROX指数的截止值，用于将HFNC或MV的管理分类为医师的临床决策，大约是6.1。HFNC和MV在胸部CT上的LIV临界值为35.5％。使用ROX指数和LIV，使用方程获得了对HFNC或MV的截止分类，LIV=4.26×(ROX指数)+7.89。接收器工作特性曲线下的面积，作为分类的评估指标，使用ROX指数和LIV均可提高至0.94,敏感性为0.79,特异性为0.91.
■医师选择HFNC氧疗或MV的呼吸治疗相关的经验决策可以通过从胸部CT图像计算的ROX指数和LIV指数的组合来支持。
