The new movie Awake that is to be released this April has a scene where the protagonist wakes up on the operating table. The film has already caused a scare among people in the US and UK who wonder at the probability of such an occurrence.
According to Britain's top anesthetists, as many as one or two people per 1,000 experience awareness after being given a general anesthetic.
'The anesthetist has to balance the risks of awareness with those of harming the patient by giving too much anesthesia,' explains Dr Keith Myerson, spokesman for the Royal College of Anesthetists and a consultant anesthetist in Eastbourne, East Sussex.
'Anesthetic 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 anesthesia - for example those with a weak heart - and the side effects of anesthetic drugs may be more dangerous in certain types of operation, such as cardiac surgery or emergency surgery for major trauma. In these cases, the anesthetist may need to use less anesthetic to avoid the risk of stroke or heart attack, and the chances of awareness are thus increased,' Dr. Myerson said.
The balance of risks is extremely challenging when general anesthesia is used during an emergency Caesarean. Enough anesthesia must be given to the mother to render her unconscious during major surgery and this needs to be done 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 anesthetic drugs,' say experts.
'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 traumatized: when they are awake and cannot move, they come to the catastrophic but erroneous conclusion that they are permanently paralyzed.'
Anesthetists are of the opinion that there is no cause for panic because patients are monitored visually and mechanically by the anaesthetist during surgery. Pupil response, sweating, tear production and sudden increases in heart rate and blood pressure are closely watched and the amount of anesthetic breathed in and out by the patient is also measured.