Utility of the ROX Index in Predicting Intubation for Patients With COVID-19–Related Hypoxemic Respiratory Failure Receiving High-Flow Nasal Therapy: Retrospective Cohort Study

Maulin Patel,Nathaniel Marchetti,Andrew Gangemi,Lauren Tragesser,Zachariah Dorey-Stein,Ibraheem Yousef,Julie Giurintano,Nicole Patlakh,Huaqing Zhao,Parth Rali,Matthew Gordon,Robert Marron,Matthew Zheng,Junad Chowdhury,Nicole Mills,Rohit Gupta,Gilbert D'Alonzo,Gerard Criner

doi:10.2196/29062

Abstract

BackgroundThe use of high-flow nasal therapy (HFNT) to treat COVID-19 pneumonia has been greatly debated around the world due to concerns about increased health care worker transmission and delays in invasive mechanical ventilation (IMV). Herein, we analyzed the utility of the noninvasive ROX (ratio of oxygen saturation) index to predict the need for and timing of IMV.ObjectiveThis study aimed to assess whether the ROX index can be a useful score to predict intubation and IMV in patients receiving HFNT as treatment for COVID-19–related hypoxemic respiratory failure.MethodsThis is a retrospective cohort analysis of 129 consecutive patients with COVID-19 admitted to Temple University Hospital in Philadelphia, PA, from March 10, 2020, to May 17, 2020. This is a single-center study conducted in designated COVID-19 units (intensive care unit and other wards) at Temple University Hospital. Patients with moderate and severe hypoxemic respiratory failure treated with HFNT were included in the study. HFNT patients were divided into two groups: HFNT only and intubation (ie, patients who progressed from HFNT to IMV). The primary outcome was the value of the ROX index in predicting the need for IMV. Secondary outcomes were mortality, rate of intubation, length of stay, and rate of nosocomial infections in a cohort treated initially with HFNT.ResultsOf the 837 patients with COVID-19, 129 met the inclusion criteria. The mean age was 60.8 (SD 13.6) years, mean BMI was 32.6 (SD 8) kg/m², 58 (45%) were female, 72 (55.8%) were African American, 40 (31%) were Hispanic, and 48 (37.2%) were nonsmokers. The mean time to intubation was 2.5 (SD 3.3) days. An ROX index value of less than 5 at HFNT initiation was suggestive of progression to IMV (odds ratio [OR] 2.137, P=.052). Any further decrease in ROX index value after HFNT initiation was predictive of intubation (OR 14.67, P<.001). Mortality was 11.2% (n=10) in the HFNT-only group versus 47.5% (n=19) in the intubation group (P<.001). Mortality and need for pulmonary vasodilators were higher in the intubation group.ConclusionsThe ROX index helps decide which patients need IMV and may limit eventual morbidity and mortality associated with the progression to IMV.

Highlights

December 2019 was marked by a cluster of acute respiratory illnesses known as COVID-19, caused by the novel coronavirus SARS-CoV-2
The ratio of oxygen saturation reverse transcriptase–polymerase chain reaction (RT-PCR) (ROX) index helps decide which patients need invasive mechanical ventilation (IMV) and may limit eventual morbidity and mortality associated with the progression to IMV
Rapid progression of hypoxemic respiratory failure from mild dyspnea to acute respiratory distress syndrome (ARDS) within 48 to 72 hours has been noted in early studies [9,11]

Summary

Introduction

December 2019 was marked by a cluster of acute respiratory illnesses known as COVID-19, caused by the novel coronavirus SARS-CoV-2. There is ongoing controversy concerning the optimal mode of respiratory support to treat COVID-19–associated hypoxemic respiratory failure. The timing and adequacy of noninvasive forms of oxygen support (ie, high-flow nasal therapy [HFNT], simple face mask usage, etc) versus invasive mechanical ventilation (IMV) is not known. A mortality rate greater than 90% has been reported [3,4,5,6]. Utilization of IMV has been greatly influenced by concerns for viral aerosolization and subsequently health care transmission through the use of noninvasive forms of oxygen support [10]. The use of high-flow nasal therapy (HFNT) to treat COVID-19 pneumonia has been greatly debated around the world due to concerns about increased health care worker transmission and delays in invasive mechanical ventilation (IMV). We analyzed the utility of the noninvasive ROX (ratio of oxygen saturation) index to predict the need for and timing of IMV

Methods

Results

Conclusion