George Michael is being kept on a special hospital bed which has "probably saved his life" in his battle against pneumonia.
The Careless Whisper singer is being cared for on the £100,000 bed designed for critically-ill lung patients, in the intensive care room of the AKH Hospital in Vienna, Austria.
Dr Carol Cooper told The Sun newspaper: "The bed has probably saved his life so far. But he is far from out of the woods yet."
Fans and family are worried as it was claimed last night the star has developed Acute Respiratory Distress Syndrome - a lung condition often caused by pneumonia, which stops oxygen getting into the blood, and is potentially-fatal.
George is strapped into the Triadyne Proventa 'kinetic therapy' bed, designed for people in acute respiratory distress who cannot move, and it constantly tilts from side to side up to 40 degrees, to relieve pressure on his lungs.
Dr Cooper added: "These beds are lifesavers and exceptionally expensive, even to use.
"With the lungs not functioning well, the heart has to pump harder to shift the blood around the body, which would make it harder to survive.
This bed tries to get the lungs functioning as best they can.
"The movement helps shift secretions inside the lung to make sure they don't collect and make you worse. But if he is still being cared for like this, he is very seriously ill.
"He is in a critical condition, which means he could die. We still don't know why pneumonia affects some people more than others. But if you are middle-aged, and maybe with other problems such as with your immune system, your outlook is not so good."
Survivors of Acute Respiratory Distress Syndrome may suffer memory loss or other mental issues during their recovery because of the lack of oxygen to the brain. It can also be accompanied other organ failure, such as the kidney or liver.
He is thought to be under the surveillance of a kidney specialist and on a special breathing machine.
His rumoured boyfriend, Fadi Fawaz, 38, said yesterday: "George is doing well and is in good spirits - getting stronger all the time."
The singer was rushed to hospital last week and on Friday cancelled the rest of his current Symphonica Tour.
- BANG! Showbiz