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Lower rate of awareness under anaesthesia than previously thought

One episode in every 15,000 cases in 2011, national survey shows

Caroline White

Wednesday, 13 March 2013

The rate of patient awareness while under general anaesthesia is much lower than previously thought, suggest the results of a national survey of UK anaesthetists.

The Royal College of Anaesthetists (RCoA) and the Association of Anaesthetists of Great Britain and Ireland (AAGBI) asked all senior anaesthetists in NHS hospitals in the UK to report how many cases of accidental awareness during general anaesthesia they had come across in 2011.

The survey is part of the Fifth National Audit Project (NAP5), which is thought to be the largest of its kind. The findings are published in Anaesthesia and The British Journal of Anaesthesia.

More than 80% of those contacted replied, and their responses indicate one episode in every 15,000 general anaesthetics, 3 million of which are administered every year. This is significantly lower than previous reports have suggested. These put the figure at around one episode in every 500 general anaesthetics.

But the responses also suggest poor uptake of brain monitoring technology, which could indicate whether a patient is aware while under general anaesthesia, with only 2% of anaesthetists routinely using it.

“We identified accidental awareness during anaesthesia as something which concerns patients and the profession. The profession is therefore undertaking this major study so that we can better understand the problem and work to reduce the likelihood of it happening to patients,” explained lead author Professor Jaideep Pandit.

“Although we know that some patients do suffer distress after these episodes, our survey has found that the vast majority of episodes are brief and do not cause pain or distress.”

He said that the study would be looking at the discrepancies between the current and previous figures, to see if factors, such as differences in patient sensitivity to anaesthetic drugs or different detection rates could explain them.

Co –author Professor Tim Cook, emphasised that risks to patients undergoing general anaesthesia are very small and have fallen over the past few decades.

“Of the three million general anaesthetics administered in the NHS each year, only a very small number of patients experience awareness during anaesthesia, with the majority of these occurring before surgery starts or after it finishes,” he said.

“While our findings are generally reassuring for patients and doctors alike, we recognise that there is still more work to be done. We are spending the next year studying as many of the cases as possible to learn more from patients’ experiences,” he added. The final report is expected early in 2014.

A national survey of anaesthetists (NAP5 Baseline) to estimate an annual incidence of accidental awareness during general anaesthesia in the UK

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