Conservative Versus Conventional Oxygen Administration in Critically Ill Patients

Oxygen supplementation in the inspired mixture is commonly used in critically ill patients and observational studies highlight that those patients remain hyperoxemic for substantial periods during Intensive Care Unit stay. However, exposure to inhaled oxygen-enriched mixtures is widely recognized as potentially harmful and cause of organ damage. Although, the specific level of arterial oxygen partial pressure (PaO2) considered harmful, or the dangerous duration of hyperoxia, is not determined yet as there are no clinical trials on humans that evaluate the appropriate percentage of oxygen considered safe to maintain an adequate tissue oxygen availability. The study is designed as a multicentre, open-label, two parallel groups, randomized superiority clinical trial. The study will involve 10 European intensive care units and will recruit adult critically ill patients requiring mechanical ventilation with an expected length of stay of more than 72 hours admitted to the Intensive Care Unit. Within the conventional group, participants will receive an inspired oxygen fraction (FiO2) aiming to maintain an oxygen saturation by pulse oximetry (SpO2) equal or major than 98 percentage, accepting an upper limit of PaO2 of 150 mmHg and a lower limit of 60 mmHg. Patients in the conservative group will receive the lowest FiO2 to maintain SpO2 between 94 and 98 percentage, or when available a PaO2 between 60 mmHg and 100 mmHg. The primary objective of this study is to verify the hypothesis that strict maintenance of normoxia improves survival in a wide population of mechanically ventilated critically ill patients compared to the application of conventional more liberal strategies of oxygen administration. Survival will be measured at Intensive Care Unit discharge. The confirmation of the efficacy of a conservative strategy for oxygen administration in reducing the mortality rate among critically ill patients will lead to a profound revision of the current clinical practice and a