Today this dangerous situation has been largely alleviated. Henry, a 77-year-old pensioner from East London, still lives alone and happily practices golf swings in his back garden safe in the knowledge that his body is able to cope with the extra exertion.

What has altered Henry's life is not some wonder drug but a simple change in the way his illness is managed. Every day Henry hooks himself up to monitoring devices whose results are helped him to understand it and overcome its more debilitating effects. "Telehealth has given me confidence in myself because I know my own body now," he says. He adjusts what he does according to what his daily readings tell him about his condition.

Henry is just one of a growing number of pioneering patients who are trusting their futures to telehealth. Large trials are under way around the world to evaluate the idea. With elderly populations and the incidence of age-related illnesses growing telehealth promises to give people the independence they need to remain in their own homes. It could also reduce the burden of healthcare costs.

The disorder that makes Henry's life so difficult is chronic obstructive pulmonary disease (DOPD), a condition that affects some 800 000 people in England. The airways in his lungs have narrowed, leaving him with severe shortness of breath and blood oxygen levels that can fall dangerously low.

With his new equipment, Henry can keep a close eye on how his body is doing. He received for measuring his blood oxygen level and pulse rate, a blood pressure monitor and a set of speaking scales. Each connects wirelessly to a unit collates the readings and sends them to a team of medical specialists, who watch for suspicious changes, if the readings look bad, they call him to discuss appropriate action. Henry too can see the readings on his television, where they are displayed with the help of a special set-top box.

Whether a day is good or bad depends largely on Henry's blood oxygen level. Before joining the telehealth program, he could only guess at that. Now he knows if the reading is low, he can take action. When the reading is high, he can go about his business confident that his oxygen level will see him through. "Telehealth is a good thing for me," says Henry. "I know that on the other end of the telephone there's a little angel and if anything goes wrong it shows up on the television and she's on the phone within five minutes."