When I talk to patients before anaesthesia one of their commonest concerns is the risk of awareness or being awake during their operation, so the publication of a national audit on accidental awareness under anaesthesia (AAGA) is an important milestone. British anaesthesia leads the world in these audits which are called national audit projects. This was the fifth national audit hence the term NAP5 and collected data from the United Kingdom and Ireland over a period of a year.
Perhaps the most surprising finding was that the commonest reports were not from patients having a general anaesthetic but from patients receiving sedation. Sedation consists of giving drugs intravenously to remove anxiety and is often used for procedures such as endoscopy or in conjunction with local anaesthetic blocks for operations such as those we undertake on the feet. I always tell patients that they will be awake and aware during sedation although they may forget their experiences because the drugs can produce amnesia. It appears that many patients did not receive a proper explanation and I suspect this is why they found the experience so upsetting. It is almost unknown in my practice to force the patient to have sedation and if I believe a patient is psychologically ill-prepared or excessively anxious I will always choose general anaesthesia for them.
The true incidence of awareness remains unknown because many reports during the year were from anaesthetics given some time before. This in itself is of concern because it implies that many patients are reluctant to report awareness. NAP5 demonstrated that 80% of awareness was distressing and produced symptoms similar to post-traumatic stress syndrome. These patients would have benefited from early treatment but did not receive it.
The incidence reported in NAP5 was 1:6000 but we believe that the true frequency is as high as 0.1%. There is no one single cause. Awareness is more likely with emergency anaesthetics and at the beginning and the end of anaesthesia. It is more common in obstetrics, cardiac surgery and the obese. It is uncommon in children. Anaesthetic techniques which use only intravenous drugs and those which use paralysing agents are particularly at risk.
As a result of NAP5 there have been suggestions that we should have checklists but I doubt these will make a significant difference. I believe and have always believed that it is important to ensure an adequate depth of anaesthesia and the use of adequate amounts of reliable drugs. It is rare to have problems with the heart or breathing and running patients ‘light’ is rarely necessary. With new techniques I can undertake the majority of anaesthetics without paralysing my patients. I avoid total intravenous anaesthesia wherever possible because a slight reduction in nausea or a few minutes faster recovery does not justify the catastrophic trauma of awareness. Most importantly I monitor the depth of anaesthesia with a continuous EEG.
I hope that the risk of awareness in my patients is below the average. I also benefit because I do not do obstetric anaesthesia and most private practice is elective in nature. I do however believe it is important for patients to report awareness as early as possible even if the event has not been distressing. Early psychotherapy can make a significant improvement and when I was at St Bartholomew’s Hospital we were one of the first units in the UK to have a formal policy to refer to our psychology colleagues. Other family members can also help by directly asking patients whether they had awareness if the patient appears withdrawn or depressed after an operation.

About the author

Dr Aubrey Bristow is a consultant anaesthetist in central London. These articles are his personal views and reflect individual issues of interest to patients. They are not a comprehensive review of the subject nor a substitute for a consultation with your anaesthetist.