While most episodes of accidental awareness while under general anaesthesia are short-lived, they can lead to long-term psychological distress, a major new study carried out in Ireland has found.

General anaesthetics are medications that cause patients to lose consciousness so that they are unaware of surgery. Accidental awareness during general anaesthesia (AAGA) occurs when the medication does not work properly and the patient remains conscious.

According to this latest study, it is one of the most feared complications of general anaesthesia for both patients and anaesthetists.

The study, known as NAP5, was carried out over the last three years by the Royal College of Anaesthetists (RCoA) and the Association of Anaesthetists of Great Britain and Ireland (AAGBI).

The researchers studied some three million general anaesthetics from every public hospital in Ireland and the UK, focusing on over 300 new reports of AAGA. Eleven of these were in Ireland.

They found that most episodes of awareness are short and occur before or after surgery. When they occur, they do not always cause a problem for the patient. However in 51% of cases studied, patients said they were distressed by the occurrence, while 41% felt they had been psychologically harmed in the long-term.

Sensations experienced during AAGA included pain, paralysis, choking, stitching and tugging. Affected patients described feelings of panic, fear and suffocation. Some even said they felt like they were dying.

Long-term psychological harm was linked to features of post-traumatic stress disorder (PTSD).

One adult patient described her experience of AAGA when she was 12 years old and was having a routine orthodontic operation.

"Suddenly, I knew something had gone wrong. I could hear voices around me and I realised with horror that I had woken up in the middle of the operation, but couldn't move a muscle... while they fiddled. I frantically tried to decide whether I was about to die," she said.

According to Dr Ellen O'Sullivan, president of the College of Anaesthetists and the study's lead, this is ‘by a considerable margin' the biggest study of AAGA ever carried out worldwide.

"It has studied outcomes from all anaesthetics in five countries for a full year. Notwithstanding the smaller size of the study in Ireland compared with the UK, the number and types of AAGA in Ireland has remarkable similarities to the UK and can be seen as a form of validation of the UK Project," she noted.

The study found that the incidence of spontaneous reports of AAGA was much lower than previously estimated, with one in every 19,000 patients reporting it. When patients are specifically asked about AAGA after an operation, this figure rises to one in 600.

Meanwhile the researchers made a number of recommendations for changes in clinical practice. Two of the main recommendations are:
-The introduction of a simple anaesthesia checklist to be performed at the start of every operation
-The introduction of an Awareness Support Pathway - a structured approach to the management of patients reporting awareness.

The researchers believe that these two recommendations could decrease errors that cause awareness and minimise the psychological consequences if AAGA occurs.