It is many people's worst nightmare.
But for one young man it became reality as he woke up in agony during a lung operation but was unable to tell the surgeons what had happened because he'd been temporarily paralysed by medication.
Mathias Strom - from Vaxjo, southern Sweden - could feel every cut of the surgeon's scalpel and listened to the medical team chatting about his progress as he endured 35 minutes of agony before passing out because of the pain.
Nightmare: The man was awake and could feel what the surgeons were doing - but couldn't move (file photo)
In a formal complaint into the collapsed lung op he said: 'It was a terrible experience, my worst nightmare.
'I could hear the doctors and nurses speaking and the pain became more and more intense.
'My brain kept telling me over and over, "Say your name, say something, do something to let them know, wiggle your toes".
'But I was completely incapable of saying something or moving my body at all.
'My first words when I woke up were of real anger, I told them ‘What the hell have you done? Hell, my back hurts, where was the anaesthesia?'.
Agony: Mathias Strom, 22, endured 35 minutes of horrific pain before passing out because it was so bad (file photo)
At first doctors had doubted the story believing that it had been a dream – but after he accurately reported details of who had been present and what they had spoken about – the anaesthetist was called and admitted that there had been some indications that the operation was not going as normal.
However none of the medical staff had elaborated after this admission and after failing to get satisfaction for his ordeal – he decided to take it further.
He said: 'If anybody had been able to give me a satisfactory explanation and apology I might not have taken it this far. But the fact is I've heard nothing.'
The incident had happened in March and only came to light after the man wrote to the National Board of Health and Welfare (Socialstyrelsen) to complain.
Hospital management however declined to comment, saying that they had not been informed about the complaint and would not say anything until they had more details.
In the complaint he said he had been awake for over half an hour of the operation, which his records had shown had taken place for about 50 min.
He said he had woken up after 15 minutes and then had to endure the ordeal until he passed out.
He said he had woken up after 15 minutes and then had to endure the ordeal until he passed out.
He added that since the incident he suffered from nightmares and would wake up fearing that the incident was being repeated again.
He said: 'It is still difficult - it was the worst thing I could imagine. I still find it hard to sleep.
Read more: http://www.dailymail.co.uk/health/article-2134755/The-stuff-nightmares-Man-comes-lung-operation-communicate-anaesthetic.html#ixzz1t3sacImt