Early Measurement of ROX Index in Intermediary Care Unit Is Associated with Mortality in Intubated COVID-19 Patients: A Retrospective Study

Abstract

COVID-19 patients often present with rapidly progressing acute hypoxemic respiratory failure, requiring orotracheal intubation with different prognostic issues. However, ICU specialists lack predictive tools to stratify these patients. We conducted a single-center cross-sectional retrospective study to evaluate if the ROX index, measured under non-invasive oxygenation support, can predict ICU mortality in a COVID-19 intubated patient cohort. This study took place in the division of intensive care at the Geneva University Hospitals (Geneva, Switzerland). We included all consecutive adult patients treated by non-invasive oxygenation support and requiring intubation for acute respiratory failure due to COVID-19 between 9 September 2020 and 30 March 2021, corresponding to the second local surge of COVID-19 cases. Baseline demographic data, comorbidities, median ROX between H0 and H8, and clinical outcomes were collected. Overall, 82 patients were intubated after failing a non-invasive oxygenation procedure. Women represented 25.6% of the whole cohort. Median age and median BMI were 70 (60–75) years and 28 (25–33), respectively. Before intubation, the median ROX between H0 and H8 was 6.3 (5.0–8.2). In a multivariate analysis, the median ROX H0–H8 was associated with ICU mortality as a protective factor with an odds ratio (95% CI) = 0.77 (0.60–0.99); p < 0.05. In intubated COVID-19 patients treated initially by non-invasive oxygenation support for acute respiratory failure, the median ROX H0–H8 could be an interesting predictive factor associated with ICU mortality.

Delayed intubation is associated with mortality in patients with severe COVID-19: A single-centre observational study in Switzerland

“…Until now, it has not been possible to identify COVID-19 patients who may benefit from early vs. late intubation. The ROX index, defined as the ratio of oxygen saturation as measured by pulse oximetry/FiO2 to the respiratory rate, has been proposed to detect patients who need intubation in ARDS [30] and a recent study has suggested it as a predictive tool to identify severe COVID-19 patients requiring early intubation [31] .…”

Role of prognostic scores in predicting in-hospital mortality and failure of non-invasive ventilation in adults with COVID-19

“…Its limited discriminative value at the beginning of the treatment could be due to the limited accuracy of the SpO 2 measurement in the presence of very low values (< 80%), with consequent impossibility to distinguish true and false low SpO 2 [25,26]. ROX index has already been employed in subjects with COVID-19 treated with HFNC as well as with NIV, to early identify those at high risk of failure, with good results [27][28][29] but different cut-offs have been adopted by different studies. In this population, a value < 4.88, the usual suggested cut-off, was significantly more common among those with an adverse prognosis from Day + 2, but it did not show an independent association with an increased mortality rate.…”

The Respiratory Rate-Oxygenation Index predicts failure of post-extubation high-flow nasal cannula therapy in intensive care unit patients: a retrospective cohort study

“…In these patients, a high ROX index (7.0 or higher) was a protective factor for mortality in the ICU and at 28 or 30 days. ( 27 - 29 ) However, there is no evidence that relates the ROX index in extubated patients who receive HFNC as a bridge therapy and mortality rates. Our study did not find significant differences between the ROX index in patients who died during the ICU stay and those who survived.…”