There's no conclusive evidence that hyperbaric oxygen therapy — which involves breathing pure oxygen in a special pressurized chamber — improves the outcome of stroke.
Some researchers theorize that increasing the supply of oxygen to the parts of the brain affected by stroke may reduce the extent of irreversible damage. But this has not been proved. Too few people have been studied to say whether hyperbaric oxygen therapy decreases the chance of dying or if it offers other benefits, such as improving the ability to perform everyday tasks.
Although hyperbaric oxygen therapy has been found useful in the treatment of a number of conditions — such as decompression sickness and carbon monoxide poisoning — more research is needed to evaluate what, if any, role it plays in stroke treatment.