Effect of normobaric hyperoxia in ischaemic stroke

442 www.thelancet.com Vol 405 February 8, 2025 In ischaemic stroke, discontinuation of local arterial blood supply to the brain leads to neurological deficits. The assumption that increased delivery of oxygen in patients with acute ischaemic stroke might lead to amelioration of neurological deficit is interesting, but almost all large clinical trials were neutral, with no effect compared with usual care. Similar studies in patients with other serious illnesses were also neutral.
In hindsight, animal experiments might have warned us that administering high concentrations of oxygen to patients with ischaemic stroke without adequate reperfusion might not be effective. [...]

The OPENS-2 trial was rather small, and consequently, the significant effect was quite large, with an average shift of more than 10% in the direction of more favourable outcome on the modified Rankin Scale. Although the generally consistent effect on other outcome parameters is reassuring, nevertheless, we can expect the true effect of normobaric hyperoxia to be smaller than reported here. Therefore, these promising results require confirmation in larger trials and, encouragingly, at least one trial has started recruitment (NCT06666764).