Factors Associated With Non-invasive Oxygen Therapy Failure in COVID-19 Pneumonia: A Single Center, Retrospective Study in a Tertiary Hospital in North India.

Background: Non-invasive oxygen therapy (NIT) consists of high-flow nasal oxygen (HFNO) and continuous positive airway pressure (CPAP). NIT is routinely being used for the management of acute respiratory failure secondary to coronavirus disease-2019 (COVID-19) with variable outcomes. However, previously published studies show that NIT failure might delay endotracheal intubation and invasive mechanical ventilation and results in worse outcomes in patients with hypoxemic respiratory failure. Early prediction of failure of NIT, will help in early decision-making in initiating invasive mechanical ventilation. We retrospectively studied the predictors for NIT failure in patients with moderate to severe COVID-19.

Methods: Adult patients (>18 years) admitted to the intensive care unit (ICU) with moderate to severe COVID-19 ARDS and received NIT [HFNO and CPAP non-invasive ventilation (NIV)] were included in this study. Baseline clinical and laboratory data were collected retrospectively from the electronic hospital information system. NIT failure was defined as the need for invasive mechanical ventilation after the initiation of NIT in the ICU. Univariate and multivariate logistic regression analyses were used to find out the possible predictors of NIT failure.

Results: Out of 254 patients admitted to ICU, 127 patients were initiated NIT at admission to ICU. During the course of the ICU stay, 33 (26%) patients subsequently required invasive mechanical ventilation (NIT failure). Respiratory rate-oxygenation index (ROX index) of <2.97 at two hours and <3.63 at six hours of ICU admission predicted NIT failure in our cohort of patients with a high positive predictive value.

Conclusion: Patient selection is crucial for successful NIT in COVID-19. Application of ROX index measured in the first six hours of ICU admission helps in the identification of patients at risk of NIT failure with moderate to severe COVID-19 ARDS.