Predictors of failure with high-flow nasal oxygen therapy in COVID-19 patients with acute respiratory failure: a multicenter observational study

Abstract

Purpose We aimed to describe the use of high-flow nasal oxygen (HFNO) in patients with COVID-19 acute respiratory failure and factors associated with a shift to invasive mechanical ventilation. Methods This is a multicenter, observational study from a prospectively collected database of consecutive COVID-19 patients admitted to 36 Spanish and Andorran intensive care units (ICUs) who received HFNO on ICU admission during a 22-week period (March 12-August 13, 2020). Outcomes of interest were factors on the day of ICU admission associated with the need for endotracheal intubation. We used multivariable logistic regression and mixed effects models. A predictive model for endotracheal intubation in patients treated with HFNO was derived and internally validated. Results From a total of 259 patients initially treated with HFNO, 140 patients (54%) required invasive mechanical ventilation. Baseline non-respiratory Sequential Organ Failure Assessment (SOFA) score [odds ratio (OR) 1.78; 95% confidence interval (CI) 1.41-2.35], and the ROX index calculated as the ratio of partial pressure of arterial oxygen to inspired oxygen fraction divided by respiratory rate (OR 0.53; 95% CI: 0.37-0.72), and pH (OR 0.47; 95% CI: 0.24-0.86) were associated with intubation. Hospital site explained 1% of the variability in the likelihood of intubation after initial treatment with HFNO. A predictive model including non-respiratory SOFA score and the ROX index showed excellent performance (AUC 0.88, 95% CI 0.80-0.96). Conclusions Among adult critically ill patients with COVID-19 initially treated with HFNO, the SOFA score and the ROX index may help to identify patients with higher likelihood of intubation.

ROX index as predictor of high flow nasal cannula therapy success in acute respiratory failure due to SARS-CoV-2

“…Regarding ROX index cut-off points to predict success of HFNC therapy in COVID-19, different studies reported similar points to those proposed by Roca et al 27 and Hu et al11, with a population similar to ours in terms of demographics and comorbidities, concluded that 6 hours after HFNC onset with a cut-off point at 5.55 was the most suitable predictor of HFNC success, albeit with a relatively low sensitivity (61.1%) and relatively high specificity (84.6%); in contrast, in the present study the best predictor of HFNC success is the ROX index 24h after therapy onset, with a cut-off point of 5.35, which yielded better results in sensitivity, specificity, PPV, NPV and AUC than those proposed by other studies.10, 11, 13, 28 Recently have been published prospective studies evaluating utility of ROX index in COVID. 29 , 30 , 31 Mellado-Artigas et al, 29 in a multicenter prospective study that included 259 patients with severe pneumonia due to SARS-CoV-2 who reveived HFNC at ICU admission, found that baseline non-respiratory Sequential Organ Failure Assessment (SOFA) score and ROX index were associated with endotracheal intubation and mechanical ventilation. Suliman et al, 30 in a prospective study that included 69 patients with moderate and severe COVID found that ROX index measured on the first day of admission was independent predictor factor of intubation with a cut-off point <25.26; a very high cut-off point is striking in this study, 30 fact for which it was not included in a recent meta-analysis.…”

Noninvasive respiratory support and patient self-inflicted lung injury in COVID-19: a narrative review

“… 121 A single multicentre observational study identified the SOFA score and the ROX index as predictive tools for respiratory failure and endotracheal intubation during HFNOT in COVID-19. 122 Moreover, in the early stage, when elastance is relatively preserved, respiratory rate is not particularly high, but tidal volumes could be. 123 Consequently, transpulmonary pressure and changes in pleural pressure are preponderant, with possible haemodynamic consequences.…”

Use of HFNC in COVID-19 patients in non-ICU setting: Experience from a tertiary referral centre of north India and a systematic review of literature

“…Several other tools have been used to predict failure of HFNC particularly the ROX index which has shown promise as its role has been replicated in several studies in diverse settings. [21] However the most appropriate cut-off value for ROX to optimally predict HFNC failure varies widely in in ward (ROX cut-off of 2.2[9], 5.5 [22]and 5.9 [23]) as well as ICU settings (4.8 [24] and 5.37 [25]). Unfortunately, the retrospective nature of the present study did not allow us to track the ROX consistently in all our patients .…”