A mobile phone millionaire is to be a guinea pig in a health experiment on Mount Everest.
Mr Caudwell sold his business for an estimated £1bn
John Caudwell has donated £500,000 and will take part in research to help save the lives of intensive care patients.
The ex-Phones4U chief will climb Everest in March as part of a pioneering study to look at how the human body adapts to low oxygen levels.
The £1.5m Xtreme Everest experiment will see 40 doctors and 200 volunteers climb up and down the mountain.
Their brain, lung and circulation levels will be tested before they trek up the mountain and at various altitudes.
Medics hope to become the first in the world to take blood samples at such a great height.
It is hoped that the study will help doctors understand more about how critically-ill patients react to low oxygen levels in the blood and how to improve treatment.
Everest is 29035 feet (8850 metres) high
Mr Caudwell, 54, said: "I have never done anything like this before. There's always a nervous apprehension when you take on a big challenge.
"You never quite know what's going to happen, especially when there's the risk of altitude sickness.
"If this research is successful, and they have a strong feeling that they are going to produce results, it will help thousands of people who go into intensive care, which is something I think is worth supporting."
The study has attracted worldwide attention with doctors across the globe hoping to use the results to help their patients.
The project was initiated by University College, London.
Expedition leader Dr Mike Grocott said: "We hope it will increase our understanding of what is making critically-ill people ill and give us the opportunity to develop treatments to help.
"The research is very significant and could help people in intensive care around the world."