key: cord-0853307-4muqfakb
authors: Goury, Antoine; Moussanang, Jean‐Adoumngar; Bard, Mathieu; Champenois, Vanessa; Julien, Gautier; Dupont, Vincent; Mourvillier, Bruno
title: Predictive factors associated with high‐flow nasal cannula success for COVID‐19‐related acute hypoxemic respiratory failure
date: 2021-05-07
journal: Health Sci Rep
DOI: 10.1002/hsr2.287
sha: 6c86d8010de87c6323fd160a65ef35885ae33dcb
doc_id: 853307
cord_uid: 4muqfakb

nan

During the coronavirus disease 2019 (COVID-19) pandemic, oxygen support management for critically ill patients with acute hypoxemic respiratory failure (AHRF) was a key component of clinical decisionmaking. 1 There is a lack of knowledge regarding the use of high-flow nasal cannula (HFNC) in COVID-19 patients with AHRF. Most hospitals adopted an early-intubation strategy leading to a high intubation rate and the demand for intensive care unit (ICU)-beds overwhelmed hospital resources. With a low ICU bed-to-population ratio in our area, we adopted a large high-flow nasal cannula (HFNC) therapy use in COVID-19 patient-related AHRF. Here, we assessed, retrospectively, the benefit of HFNC use in this population.

Forty-two COVID-19-confirmed patients with AHRF treated with at least 2 hours of HFNC in first line were included in the study between March 1 and May 23, 2020 ( Figure 1 ). The study was declared at European General Data Protection Regulation (Identifier RMR004-25052020). Inclusion criteria were laboratory-confirmed COVID-19 patients over 18 years of age suffering from AHRF treated with HFNC as first-line therapy and admitted to the medical ICU of the Reims University Hospital. Exclusion criteria were under 18 years of age, urgent need to intubate (less than 2 hours after HFNC initiation), previous intubation in the same hospital stay, and presence of a do-not-resuscitate order.

HFNC was initiated with a minimum flow of 50 L/min with a FiO 2 of 50%. Then, FiO 2 was titrated targeting an SpO 2 above 92%, and flow rate was adjusted up to 60 L/min or according to the maximum tolerated dose. HFNC failure was defined as the subsequent need for invasive mechanical ventilation. Intubation criteria were left at the discretion of physicians. Respiratory parameters were measured under HFNC conditions. The ROX index was defined as the ratio of SpO 2 /FiO 2 (%) to respiratory rate (breaths/min). In patients with AHRF treated with HFNC, a ROX index higher than 4.88 measured after 12 hours of HFNC was significantly associated with a lower risk of intubation. 2, 3 Quantitative parameters were analyzed with nonparametric tests.

Differences in categorical variables were assessed with chi-square. All tests were two-sided with a 5% significance level.

Results are displayed in Table 1 

The main finding of our study is the high rate of HFNC success (52%) in a significant cohort of COVID-19 patients with severe AHRF. These results contrast with the low success rate reported by first published series such as the study of Wang et al. 4 However, they did not use HFNC as first-line therapy, which suggests that it was used for selected patients and could therefore explain the differences of outcomes reported. Indeed, recent large cohorts of patients treated with HFNC as first-line therapy corroborated our results with a rate of success ranging from 44 to 62%. 5, 6, 8 Previous studies have reported that delayed intubation could be associated with a worse outcome in de novo AHRF patients. Here, we did not report an excess mortality in the HFNC failure group (30%), compared to patients requiring early intubation in other cohorts. 7 Similarly, Demoule et al. confirmed that HFNC was safe and could significantly reduce the intubation rate in a large cohort of 146 COVID-19 patients. 8 The first use of noninvasive ventilation has been recently reinforced by Dupuis et al which showed an increased risk of mortality at day-60 for an early mechanical ventilation strategy. 9 Zucman et al. suggest that ROX index could help for predicting HFNC outcome in this specific population from the very first hours. 10 Here, only the ROX index at H12 was associated with HFNC success. An explanation could be a different management of oxygen support in these patients with easier criteria for intubation use. Moreover, in our study, the first FIO2 reported under HFNC condition was lower than in the Zucman's study. This could suggest that patients should be selected as early as possible to benefit from HFNC which could explain their failure rate of 63% of HFNC. We also reported a higher ROX index at H2 and H6 than previous studies in cohorts of non-COVID-19 patients. 3 This is potentially The ROX index was defined as the ratio of SpO 2 /FIO 2 (%) to RR (breaths/min). The ROX index is an early marker to predicting the success or failure of HFNC. 

A national strategy for ventilator and ICU resource allocation during the COVID-19 pandemic

An index combining respiratory rate and oxygenation to predict outcome of nasal high-flow therapy

Use of nasal high flow oxygen during acute respiratory failure

Clinical course and outcomes of 344 intensive care patients with COVID-19

High-flow nasal cannula in COVID-19: outcomes of application and examination of the ROX index to predict success

Application of high-flow nasal cannula in hypoxemic patients with COVID-19: a retrospective cohort study

ICU and ventilator mortality among critically ill adults with coronavirus disease 2019

High flow nasal Canula in critically ill severe COVID-19 patients

Association between early invasive mechanical ventilation and Day-60 mortality in acute hypoxemic respiratory failure related to coronavirus Disease-2019 pneumonia

Prediction of outcome of nasal high flow use during COVID-19-related acute hypoxemic respiratory failure

COVID-19 pneumonia: different respiratory treatments for different phenotypes?

Modeling lung perfusion abnormalities to explain early COVID-19 hypoxemia

Predictive factors associated with high-flow nasal cannula success for COVID-19-related acute hypoxemic respiratory failure

Statistical analysis: Antoine Goury

Dr GOURY had full access to all of the data in this study and takes complete responsibility for the integrity of the data and the accuracy of the data analysis.

The study was declared at European General Data Protection Regulation (GRPD) (Identifier RMR004-25052020). Patients and their relatives were informed of the use of medical data and did not manifest opposition.

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

https://orcid.org/0000-0002-0014-9281