Patients report accidental awareness during general anesthesia about 1 in every 19,000 cases, according to a report published in Anaesthesia. This incidence of patient reports of awareness is much lower than previous estimates of awareness, which were as high as 1 in 600, according to a news release.
The findings come from the 5th National Audit Project, or NAP5, which was conducted over the last three years by the Royal College of Anaesthetists and the Association of Anaesthetists of Great Britain and Ireland. The researchers studied 3 million general anesthetics from public hospitals in the U.K. and Ireland and more than 300 new reports of awareness.
The study showed that the majority of episodes of awareness are short-lived, occur before surgery starts or after it finishes, and do not always cause concern to patients; however, 51% of episodes led to distress and 41% to longer-term psychological harm, according to the report. Sensations experienced included tugging, stitching, pain, paralysis and choking. Patients described feelings of dissociation, panic, extreme fear, suffocation and even dying. Longer-term psychological harm often included features of post-traumatic stress disorder.
We found that patients are at higher risk of experiencing AAGA during caesarean section and cardiothoracic surgery, if they are obese or when there is difficulty managing the airway at the start of anesthesia, Jaideep Pandit, DPhil, FRCA, professor, consultant anesthetist at Oxford University Hospitals, and project lead, said in the release. The use of some emergency drugs heightens risk, as does the use of certain anesthetic techniques. However, the most compelling risk factor is the use of muscle relaxants, which prevent the patient moving. Significantly, the study data also suggest that although brain monitors designed to reduce the risk of awareness have a role with certain types of anesthetic, the study provides little support for their widespread use.
The project report includes recommendations including the introduction of an anesthesia checklist to be performed at the start of every operation, and the introduction of an Awareness Support Pathway, a structured approach to the management of patients reporting awareness. These two interventions are designed to decrease errors causing awareness and to minimize the psychological consequences when it occurs, according to the report.
It is reassuring that the reports of awareness (1 in 19,000) in NAP5 are a lot rarer than incidences in previous studies, Tim Cook, BA, MBBS, FRCA, FFICM, professor, consultant anesthetist Royal United Hospital NHS Trust in Bath, England, and co-author of the report, said in the release. The project dramatically increases our understanding of anesthetic awareness and highlights the range and complexity of patient experiences. NAP5, as the biggest ever study of this complication, has been able to define the nature of the problem and those factors that contribute to it more clearly than ever before. As well as adding to the understanding of the condition, we have also recommended changes in practice to minimize the incidence of awareness and, when it occurs, to ensure that it is recognized and managed in such a way as to mitigate longer-term effects on patients.
Full details of the report can be found at http://nap5.org.uk/NAP5report