It is the stuff of nightmares. A patient lies upon an operating table, supposedly dead to the world, while the surgeon prepares to make the first incision. But unbeknown to the medics around him, the patient has not been fully anaesthetised and will be conscious as he goes under the knife. Paralysed by muscle relaxant drugs in the anaesthetic cocktail, he is unable to move or cry out. Nobody will hear his silent screams.

This scenario will be played out at cinemas around the country in April, when the film Awake hits our screens. In the movie, the wealthy protagonist, played by Hayden Christensen, prematurely surfaces from an anaesthetic as the surgeon is about to open his chest, and learns of a plot to murder him.

Unsurprisingly, the film has already unsettled those of a nervous disposition in the US and looks likely to do the same over here. Anaesthetists can expect much closer questioning from their pre-operative patients in the coming months.

According to the Royal College of Anaesthetists, between one and two people per 1,000 experience awareness after being given a general anaesthetic, adding up to 1,000 to 2,000 cases in the UK each year. While some anaesthetists are convinced by their own experience that the true figure is much lower - and recent US research suggests they may be right - others believe that this is an underestimate and that anaesthetic awareness is underreported by those who go though it.

Awareness usually occurs because the anaesthetist has misjudged the amount of anaesthetic required to keep the patient unconscious, and administered a muscle relaxant to ensure that he or she is absolutely still during surgery.

“The anaesthetist has to balance the risks of awareness with those of harming the patient by giving too much anaesthesia,” explains Dr Keith Myerson, spokesman for the Royal College of Anaesthetists and a consultant anaesthetist in Eastbourne, East Sussex.

“Anaesthetic drugs can lower blood pressure and reduce the supply of blood to the brain and other organs. Certain classes of patient are more at risk from anaesthesia - for example those with a weak heart - and the side-effects of anaesthetic drugs may be more dangerous in certain types of operation, such as cardiac surgery or emergency surgery for major trauma. In these cases, the anaesthetist may need to use less anaesthetic to avoid the risk of stroke or heart attack, and the chances of awareness are thus increased.”

The balance of risks is particularly delicate when general anaesthesia is used during an emergency Caesarean: sufficient drugs must be given to knock out the mother during major surgery without affecting her child.

Whether patients smoke, take prescribed or illegal drugs, have a high proportion of body fat or are habitual drinkers can affect how they respond to anaesthetic drugs. People who have endured one episode of awareness are more likely to suffer another. Some operations require higher levels of anaesthetic to obliterate consciousness. Despite sophisticated monitoring during surgery, mistakes can occur.

Studies suggest that about one patient in three who experiences awareness feels pain. But even when the analgesic element in the anaesthesia keeps people pain-free, waking up on the operating table is extremely traumatic and can do lasting psychological damage.

“It is not only about the pain,” says Michael Wang, Professor of Clinical Psychology at the University of Leicester, who has treated many patients for the after-effects of awareness. “Even those who have not experienced pain can be severely traumatised: when they are awake and cannot move, they come to the catastrophic but erroneous conclusion that they are permanently paralysed.”

Annabel Mann was a partner in a City law firm who woke up while her tonsils were being removed at a London teaching hospital in 2003. “The pain felt as if somebody was standing on my neck and ripping at it. But the worst thing was not being in control of my own body. I was begging these people I had trusted to see that something was terribly wrong and they could not.”

For Jane Ward, a lecturer who experienced awareness during a gynaecological procedure, being aware “strips you of all control. It is a violation in every respect. People say it must be like being buried alive, but it isn't at all: in that situation you can shout and scream and lash out.”

The long-term effects can be devastating. “People suffer from a particularly severe form of post-traumatic stress disorder,” says Wang. “They experience flashbacks when they feel as if they are going through the whole experience again. This can happen several times a day - when they are driving, watching television or at work. They can smell the operating theatre, hear the sounds and feel the pain.

“They may have nightmares, panic attacks and phobias. I have encountered many patients whose lives are completely and tragically undermined. Most do improve significantly after a few months but some will suffer a lifetime of problems.”

Mann suffered flashbacks and nightmares in which she saw herself lying on the operating table. Antidepressants and counselling helped, but six months after the operation she developed ME, from which she still suffers. She has been unable to work since the operation.

“I have gone from being an active woman who swam every day before work and worked out at the gym to somebody who uses a stick and a wheelchair. I had a job I loved, my own home and plenty of foreign holidays. I have lost my house, I live on benefits and I have no idea what the future holds for me. I am still fighting for compensation.”

The health authority concerned has accepted that Mann was awake during her operation but believes that this is not the cause of her health problems. In the past, it was not uncommon for patients to be disbelieved entirely or told that they had dreamt the whole episode.

“Being listened to and believed is terribly important, and so is talking to other people who have been through the same thing,” says Sally Pearson (see piece below), who has set up a website for people who, like her, have experienced awareness (www.anaestheticawareness.net).

“I thought I had dealt with everything pretty well until two years ago when, for the first time, I spoke to somebody else who had been aware during an operation and could really understand what it was like. Until then, it had been a very lonely journey for me, even though the hospital had taken what happened seriously and I had been very well supported. Some emotions came up from a very deep place.”

There is some evidence that memories can be buried so deep that they do not surface at all, or only under hypnosis. According to Wang, an unknown number of patients have no conscious recall of awareness - and therefore do not report it - but may still be affected. “Most anaesthetists underestimate how common awareness is. There are many reports of people who have developed psychological problems after an operation of which they have no memory, and I have treated patients in that category.

“What appalls me is that some anaesthetists think that if a patient has no recollection of wakefulness, then the experience does not matter. If you drink too much, you can have a blank in your memory, but nobody would claim that what happened to you during that time was of no importance.”

Improvements in surgical and anaesthetic techniques have reduced the likelihood of waking up on the operating table. Minimally invasive surgery means local or regional anaesthesia is more often used; most Caesareans are now carried out under epidural; and changes in the way anaesthetics are delivered have led to muscle relaxants being required less frequently.

Recent research in the US suggests that rates of anaesthetic awareness can be cut to one in 14,000 when strict protocols are followed. A study of 87,000 patients carried out by Southeast Anaesthesiology Consultants, a medical practice in North Carolina, identified only six cases of awareness or recall. All six patients were over 55 and had had long operations, four of them cardiac surgery.

The practice interviews all patients and asks them about the possibility of awareness soon after surgery and again a day or two later. In addition, patients are monitored visually and mechanically by the anaesthetist during surgery. “We look at pupil response, sweating, tear production and for sudden increases in heart rate and blood pressure,” says Dr Neil Randhawa, a consultant anaesthetist at the Royal National Throat, Nose and Ear Hospital in London. The amount of anaesthetic breathed in and out by the patient is also measured.

Recent technology has been directed towards reducing the chances of awareness using monitors that gauge electrical activity in the brain, although not all hospitals have these or use them at every operation.

The American Society of Anaesthesiologists has recently concluded that, although brain function monitors do reduce the incidence of awareness, there is insufficient evidence to recommend their use for all patients: instead, it should be restricted to those at high risk of wakefulness.

For the Royal College of Anaesthetists' leaflet on awareness see www.rcoa.ac.uk

Some names have been changed

'I thought I must be dying'

Sally Pearson, a teacher, was awake for about 20 minutes while her son James was delivered by emergency Caesarean section 20 years ago.

“I had always wanted a natural birth but after I had been in labour for about nine hours I was rushed into theatre because my cervix was not dilating and the baby was becoming stressed.

“I was in a lot of pain and I remember thinking that soon I would go to sleep and wake up with a baby. They gave me just enough pre-med to put me under so that I was not aware that a breathing tube was going down my throat.

“The first thing I was aware of were the voices of the medical team. I thought I was dreaming but then I felt the knife cut across my stomach, which was tight as a drum, and the warmth of the blood. The pain was terrible, excruciating. It was like being tortured.

“I tried to scream and jump off the table but I could not move a muscle. Even my eyes had been taped shut. It was like one of those dreams where something terrible is going to happen to you and you cannot get out of the way.

“Because of the breathing tube, there was no air coming from my nostrils: I thought I must be dying and that my baby would have no mother. Then I began to realise what was happening and focused all my energy on trying to remember every moment, so that I could describe it to somebody exactly.

“James was torn from my womb. I heard him cry and the surgeon tell the nurse to take him out of the room. Somebody said they did not have enough staples to stitch me up - and then there was blackness. The anaesthetist had obviously realised that the tube delivering the anaesthetic was disconnected and she reconnected it.

“As soon as I came round - much quicker than anybody expected - I told a nurse what had happened. The anaesthetist visited me later and was visibly shocked: she just kept babbling an apology.

“The hospital chaplain, who was a friend, acted as mediator. The hospital had to take it seriously. How could they not when I could repeat word for word everything that the surgeon had said when I was supposed to have been unconscious?

“I think the hospital's response helped me to deal with what happened - for example, they let me visit the operating theatre with my husband [David] - but I still suffered some post-traumatic stress symptoms. Any situation where I was powerless physically or psychologically became unbearable to me.

“David and I had always planned to have four children but after James, we put having another baby on hold. Then I had miscarriages. Was there a connection with what happened at James's birth? I was nearly 40 by then. I don't know.

“Although the awareness episode was the worst experience of my life, James's birth was definitely the best. And there is no doubt in our minds which is the more important.”

How to cope with a general anaesthetic

Before:

1. Discuss with the anaesthetist or surgeon what kind of anaesthetic will be used.

2. Ask the anaesthetist what the risk of awareness is in your particular circumstances, what monitoring will be used to prevent awareness, and how reliable it is.

3. If you smoke, cut down or give up as long as possible before the operation. Smoking increases the risk of breathing difficulties during and after surgery.

4. Tell the anaesthetist about any medical conditions you have, what medication you are on - and whether you drink or smoke.

After:

1. Modern anaesthetics leave the system quickly compared with earlier versions. Nevertheless, you may have a sore throat or headache and feel sick, tired and disorientated for a few days.

2. Do not drive, operate machinery, drink alcohol or sign legal documents for 48 hours after a general anaesthetic.

3. If you think that you have experienced awareness during surgery after being given a general anaesthetic, tell the anaesthetist as soon as possible. Early counselling and support can be helpful.

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