Inhaling 100 per centpure oxygen can be harmful to the brain, according to a small US study.
The authors strongly recommended adding carbon dioxide to oxygen, especially in resuscitation where 100 per centoxygen is seen as the "gold standard".
University of California researchers scanned the brains of 14 healthy children aged 8-15 as they inhaled pure oxygen, and then a mix of oxygen and carbon dioxide.
They found inhaling 100 per centpure oxygen over-activated the hypothalamus, triggering a set of harmful reactions and releasing hormones and neuro-transmitters that can injure the brain and heart. But adding carbon dioxide to the oxygen calmed the hypothalamus and relaxed blood vessels.
Rob Morrison, senior resuscitation officer for Darent Valley Hospital, said: "This is an interesting study and it does highlight the issue. But more research needs to be undertaken before we can consider changing practice."
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