Relationship between different levels of ROX index and the prognosis of patients receiving high-flow nasal oxygen therapy in ICU

Abstract

Abstract Objective: This study aimed investigate the relationship between different levels of ROX index and the prognosis of patients with nasal high-flow oxygen therapy in intensive care unit (ICU). Methods: In this retrospective study, we collected patients receiving high-flow nasal oxygen therapy enrolled in the intensive care unit of our hospital between 2017 and 2022 . The ROX index was calculated according to the physiological indicators of the patients on the first day of admission to the ICU, and they were divided into three subgroups: Q1 (ROX index<3.85), Q2 (ROX index 3.85-4.88) and Q3 (ROX index>4.88). Baseline clinical characteristics and clinical outcomes were compared among the three groups. The Kaplan Meier curves were drawn to compare the 28-day and 60-day survival rates of patients in the three groups, and the prognosis of patients receiving nasal high-flow oxygen therapy in the intensive care unit was further explored by subgroup analysis. COX regression analysis was used to verify the association between the three groups and these indicators. Results: A total of 517 patients with HFNC were enrolled, including 231 patients in Q1 group, 137 patients in Q2 group and 149 patients in Q3 group. Compared with the other two groups, the Q3 group had lower body temperature, heart rate, APACHE II score,serum anion gap, procalcitonin and neutrophil ratio at the beginning of admission. The number of patients with acute respiratory failure and MODS was less than the other two groups. The number of patients using noninvasive mechanical ventilation was also less than that in the other two groups. In addition, patients in Q3 group had a lower rate of death at both 28 and 60 days than those in the Q1 and Q2 groups, and survivors used noninvasive mechanical ventilation less frequently. Subgroup analysis also showed that the lower the ROX index, the higher the mortality of HFNC patients at the subgroup level. Conclusion: The ROX index at the beginning of intensive care unit admission can predict the prognosis of patients with high-flow nasal cannulas. The higher the ROX index level, the better the prognosis of patients.