Coronavirus disease 2019 (COVID-19) is a respiratory illness that can cause acute arterial hypoxemia. Treatment with invasive ventilation improves oxygenation yet results in death in over 50% of cases. The high incidence of disease has also reduced resources needed to safely deliver invasive ventilation including mechanical ventilators and intravenous sedation. Non-invasive respiratory support has been shown to be efficacious in acute hypoxemic respiratory failure from other etiologies and has the potential to reduce rates of intubation and the time spent on mechanical ventilation in COVID-19. However, it is unknown which type of support is the most effective, limiting the ability to improve clinical outcomes and appropriately allocate resources. To help guide clinical practice and policy, it is critical to understand the comparative effectiveness of two forms of non-invasive respiratory support used worldwide, continuous positive airway pressure (CPAP) delivered via a helmet interface and high flow nasal oxygen (HFNO).
