Children from the UK will undergo physical tests at an altitude of 3,500 metres in the Himalayas for research into treatment of children in intensive care with low oxygen in their blood, Great Ormond Street Hospital has said.

A group of 12 children aged eight to 16 set off on Wednesday to trek from Lukla to Namche Bazaar in Nepal, and will be tested for physiological changes at high altitude, where there is less oxygen in the air.

Mark Peters, intensive care consultant at Great Ormond Street Hospital (Gosh) who is leading the children’s expedition, said: “The testing we are doing is a world first, because at high altitude we can isolate the effect of low oxygen on otherwise healthy children. We want to describe the physiology of kids who do well at low oxygen levels, to then apply that knowledge to treat patients in intensive care.

“Research with these children will address questions like: ‘Is oxygen extracted more efficiently at altitude by the muscles?’; ‘Does the muscle ‘learn’ and alter molecular pathways to become more efficient?’.

“We know that tissue dies when it doesn’t get enough oxygen, but we also know that too much oxygen can be damaging, so we hope our findings will help us to optimise the delivery of oxygen to patients in a critical condition.”

Doctor Lee Elliot Major, who is taking part in the walk with his nine-year-old son Jack Elliot Major, a former patient at Gosh, said: “For my son and I, this is a once-in-a-lifetime trip and a chance to give a little back.

“We were lucky enough to be helped by the brilliant doctors at Great Ormond Street Hospital when we were in need, so it is wonderful to take part in a study that has the potential to help children in intensive care in the future.”

Jack said: “I’m really glad that I’m helping other children get better.”

Researchers will organise a high-altitude Easter egg hunt for the children as part of the trip.