Table 1.

COVID-19-HBO: overview of inclusion and exclusion criteria

Inclusion criteria	Aged 18–90 years
	PaO2/FiO2 (PFI) below 200 mm Hg (26.7 kPa) (based on ABG measurement)
	Suspected or verified SARS-CoV-2 infection
	At least two risk factors for increased morbidity/mortality Age above 50 years Hypertension Cardiovascular disease Diabetes or prediabetes Active or cured cancer Asthma/COPD Smoking D-Dimer >1.0 mg/L Autoimmune disease
Exclusion criteria	ARDS/pneumonia caused by other viral infections (positive for other virus)
	ARDS/pneumonia caused by other non-viral infections or trauma
	Known pregnancy or positive pregnancy test in women of childbearing age
	Patients with previous CT verified lung fibrosis more than 10%
	CT-verified or spirometry-verified severe COPD with emphysema
	Contraindication for HBO according to local guidelines*
	Not likely to need ICU admission within 7 days of screening (subjective criteria that may exclude any patients who fulfil the other inclusion criteria but where the treating physician suspect a spontaneous recovery)
	Mental inability, reluctance or language difficulties that result in difficulty understanding the meaning of study participation
	Prisoner
	Unable/risk to move patient to hyperbaric chamber

*Contraindications are described in the Standard Operations Procedure for each centre; generally, includes claustrophobia, pneumothorax, severe COPD.

ARDS, acute respiratory distress syndrome; HBO, hyperbaric oxygen.