The ratio of the oxygen saturation to fractional inspired oxygen concentration (SpO2/FiO2), measured from randomisation to day 14, hospital discharge, death. SpO2 and FiO2 (or inspired oxygen) are measured as part of routine clinical care at least 4 hourly in intensive care, and 4-6 hourly on the wards for patients receiving active management. The ratio will be derived from these data from the electronic patient record.

The ratio of the oxygen saturation to fractional inspired oxygen concentration (SpO2/FiO2), measured from randomisation to day 14, hospital discharge, death. SpO2 and FiO2 (or inspired oxygen) are measured as part of routine clinical care at least 4 hourly in intensive care, and 4-6 hourly on the wards for patients receiving active management. The ratio will be derived from these data from the electronic patient record.