Handling oxygenation targets (HOT) is standard of care in the intensive care unit (ICU), however the quality and quantity of evidence is low and potential harm has been reported. The aim of the HOT-ICU trial is to assess the overall benefits and harms of two levels of oxygenation targets in adult critically ill patients with acute hypoxaemic respiratory failure in the ICU.

Acutely ill adults with hypoxaemic respiratory failure admitted to the intensive care unit (ICU) are at risk of life-threatening hypoxia, and thus oxygen is administered. However, the evidence on the optimal level of oxygenation is of low quantity and quality with no firm evidence for benefit or harm. Importantly, liberal use of supplementary oxygen may increase the number of serious adverse events including death. The aim of the HOT-ICU trial is to assess the benefits and harms of two targets of partial pressure of oxygen in arterial blood (PaO2) in guiding the oxygen administration in acutely ill adults with hypoxaemic respiratory failure at ICU admission.

Inclusion Criteria:

• Acutely admitted to the ICU AND
• Aged ≥ 18 years AND
• Receives supplemental oxygen with a flow of at least 10 L per minutes in an open system including high-flow systems OR at least a FiO2 of 0.50 in a closed system including invasive or non-invasive ventilation or CPAP systems AND
• Expected to receive supplemental oxygen for at least 24 hours in the ICU AND
• Having an arterial line for PaO2 monitoring

Exclusion Criteria:

• Cannot be randomised within twelve hours after present ICU admission
• Chronic mechanical ventilation for any reason
• Use of home oxygen
• Previous treatment with bleomycin
• Organ transplant during current hospital admission
• Withdrawal from active therapy or brain death deemed imminent
• Fertile woman (< 50 years of age) with positive urine human gonadotropin (hCG) or plasma-hCG
• Carbon monoxide poisoning
• Cyanide poisoning
• Methaemoglobinaemia
• Paraquat poisoning
• Any condition expected to involve the use of hyperbaric oxygen (HBO)
• Sickle cell disease
• Consent not obtainable according to national regulations
• Previously randomised into the HOT-ICU trial

All original records (incl. consent forms, eCRFs, and relevant correspondences) will be archived at trial sites for 15 years. The clean electronic trial database file will be delivered to the EudraCT Database and Zenodo (https://zenodo.org/about) and maintained for 15 years and anonymised if requested by the authorities.

Study Protocol and Statistical Analysis Plan has been published. Informed Consent Form are available on the webpage (www.cric.nu/hot-icu)

Managed by the Steering Committee of the HOT-ICUT trial.