Study hypothesis: Non-invasive positive pressure ventilation delivered by helmet will reduce 28-day all-cause mortality in patients with suspected or confirmed severe COVID-19 pneumonia and acute hypoxemic respiratory failure

This will be a pragmatic parallel randomized control trial that will compare helmet nonivasive ventilation with standard of care to standard of care alone in 1:1 ratio. The trial will be implemented in multiple centers.

Inclusion Criteria:

• Suspected or confirmed COVID-19
• Aged ≥14 years old at the participating ICU. ICUs that use other age cut-off for adult patients will adhere to their local standard (16 or 18 years)
• Acute hypoxemic respiratory failure based on PaO2/FiO2 ratio <200 despite supplemental oxygen with a partial or non-rebreathing mask at a flow rate >10 L/min or above
• Intact airway protective gag reflex
• Able to follow instructions (e.g. squeeze hand on command, eye contact with care provider, stick out tongue on command, etc.)

Exclusion Criteria:

• Prior intubation during this hospital admission
• Cardiopulmonary arrest
• Glasgow coma scale <12
• Tracheostomy
• Upper airway obstruction
• Active epistaxis
• Requirement for more than one vasopressor to maintain mean arterial pressure > 65 mm Hg
• Pregnancy
• Imminent intubation
• Patients with do not intubate orders or equivalent
• Enrolled in another trial for which co-enrolment is not approved including trials on mechanical ventilation
• Patients already treated with helmet
• Patients with chronic carbon dioxide retention (PaCO2 >45)
• Previous enrolment in this trial
• The primary cause of respiratory failure is not heart failure as judged by the treating team