Health: The man who came back from the dead

Frozen casualties of the winter cold whose hearts had stopped, in some cases for hours, have been revived by doctors with a heart-lung machine normally used for cardiac surgery. Janet Boyle reports on a technique that can bring hypothermia victims back from the dead.

The cold of a Scottish winter had chilled the victims into suspended animation. But the temperature that brought them to death's door also protected their brains and other organs during the hours they spent with no detectable heartbeat. With expert care, doctors discovered, they could be brought back to life.

So far, five patients who were apparently dead have been given specialised re-warming treatment by doctors at Glasgow Royal Infirmary. Two later walked out of the hospital fit and well, and two more were brought round but later died from complications. Only the fifth could not be revived.

The four men and one woman, aged from 30 to 55, were resuscitated by doctors at the Royal's Accident and Emergency department. Two were found on the streets, two others at home, and one had been rescued from the Clyde. Gordon McNaughton, senior registrar, said: "When they arrived here their hearts had stopped and their temperatures varied between 22C and 30C, compared with the body average of 37C. It was vital to establish firstly whether the patient stood a likely chance of survival." The doctors checked their blood levels of potassium, which is released at death. A high level indicates the end of life. "Success is very unlikely in someone with a very high level of potassium," Dr McNaughton said. Where the test showed there was a chance, staff connected the patient to the heart-lung machine via tubes inserted into the groin.

The blood was removed and rewarmed to 37C by pumping it through the by- pass machine. By applying heat internally rather than externally the vital organs - heart and brain - are warmed first. If a severely hypothermic body is warmed from the outside, the blood rushes from the brain and the heart and may prevent the patient recovering. Doctors say a hypothermic body is not dead until it is warm and dead.

The cold protects the brain and vital organs while the patient's heart has stopped. But doctors cannot tell whether the patient will survive until the thawing is complete. Those who are going to survive resume a heart beat when the body temperature reaches 35C. "There have been cases reported of survival after prolonged cardiac arrest," Dr McNaughton added.

As well as by-pass treatment the patients require cardiopulmonary resuscitation with a mechanical breathing and chest-thumping machine. This avoids the chance of staff tiring, because resuscitation can take up to five hours. Previous research suggests half of patients with severe hypothermia survive. Other techniques for re-warming have been used, including introducing warm saline solution into the chest and abdominal cavities.