We read the interesting work of Romero‑Garcia and colleagues on the association between partial pressure of O₂ in arterial blood (P_aO₂) and neurological outcomes in a context of acute brain injury (ABI) [1]. This is a particularly relevant topic as the brain is highly vulnerable to excessive oxidative stress and reactive oxygen species (ROS) due to its huge dioxygen (O₂) consumption and its high polyunsaturated fatty acid and iron content. The authors showed that high P_aO₂ (hyperoxemia) was associated with poor neurological outcomes and mortality and conclude that it is important to adjust oxygenation strategies in this population [1]. It gives us the opportunity to explore the physiological effect of O₂, hyperoxemia and hyperoxia on cerebral blood flow and metabolism beyond the sole results of the present meta-analysis.