A recent study of people who have been accidentally conscious while under a general anesthetic shows it can have a long-term impact.
The patient remains conscious in about one in every 19,000 general anesthetics, said researchers led by Dr. Jaideep Pandit of Oxford University, U.K. This is known as Accidental Awareness during General Anesthesia (AAGA).
Details were gathered on three million general anesthetics from every public hospital in UK and Ireland. This included over 300 reports of AAGA, in which patients experienced sensations such as tugging, stitching, pain, paralysis, and choking. Some of the episodes were of a short duration, either before or after the surgery, and were not reported as distressing.
However, 51 percent of episodes were felt to be distressing, with patients feeling dissociation, panic, extreme fear, suffocation, and even as though they were dying.
Among the total cases of AAGA, 41 percent caused long-term psychological harm similar to post-traumatic stress disorder. This was closely linked to distress at the time of the experience.
Every report of AAGA was studied in detail by a multidisciplinary panel including patients, anesthetists, psychologists, and other professionals.
Pandit said this study was “patient-focused, dealing entirely with patient reports of AAGA.” He said, “Risk factors were complex and varied, and included those related to drug type, patient characteristics, and organisational variables.
“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. 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.”
The team presented their study at the Royal Society of Medicine conference in London on September 10, 2014.
One of the study participants, Sandra, shared her experience of AAGA during a routine orthodontic operation at the age of 12.
“Suddenly, I knew something had gone wrong, I could hear voices around me, and I realized 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.
Sandra had nightmares for several years afterwards, which featured a monster that jumped on her and paralyzed her. After 15 years of such nightmares, she says she connected them back with her operation. “After that I was freed of the nightmare and finally liberated from the more stressful aspects of the event,” she said.
Sandra’s experience shares many similarities with other affected patients. Pandit said that longer-term effects like this are closely linked to the particular sensation of paralysis during AAGA. Paralysis is felt due to the muscle relaxants often needed for safe surgery.
He states, “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.”
Co-author Dr. Tim Cook pointed out that the study was “uniquely large and broad” and described the low rate of AAGA as reassuring. “The project dramatically increases our understanding of anesthetic awareness and highlights the range and complexity of patient experiences,” he commented.
After the results were analyzed, the researchers outlined several recommendations to change clinical practice. The most important recommendations were: using a simple anesthesia checklist at the start of every operation, and having an ‘Awareness Support Pathway’ which is a structured approach for managing patients who report awareness.
Implementing these interventions will reduce the errors that cause awareness and minimize the psychological impact if it does occur, says the team.
They also call for better training and hospital support systems for anesthetists, both nationally and internationally.
Cook believes this study has defined the nature of the problem and its contributing factors 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,” he said.
Pandit, J. J. et al. The 5th National Audit Project (NAP5) on accidental awareness during general anaesthesia: protocol, methods and analysis of data. The British Journal of Anaesthesia and Anaesthesia, 9 September 2014 doi: 10.1093/bja/aeu31 http://nap5.org.uk/NAP5report