About one in every 19,000 surgical patients may experience "accidental awareness" while under anesthesia, feeling anything from paralysis to pain, according to the largest study of its kind.
For the study, researchers from the Royal College of Anaesthetists and the Association of Anaesthetists of Great Britain and Ireland analyzed data on three million operations that occurred over a single year. More than 300 of the patients involved reported accidental awareness in which they gained consciousness after being put under general anesthetic.
Most episodes were short-lived and tended to occur before the procedure began or after it was completed, researchers say. Still, 41% of the patients suffered long-term psychological harm, such as post-traumatic stress disorder, as a result of the experience.
Patients reported experiencing stitching, tugging, pain, choking, paralysis, an inability to communicate, and a "dying" feeling. About half say the incident caused them distress.
Researchers say accidental awareness was more likely to occur during cardiothoracic surgery or during Caesarean section surgeries. C-sections likely had a higher risk because of the balance needed to keep the baby awake during the procedure. Researchers say about one in 670 women who have a C-section may experience some level of awareness.
In addition, "We found that patients are at higher risk of experiencing accidental awareness during general anesthesia… if they are obese or when there is difficulty managing the airway at the start of anesthesia," says author Jaideep Pandit, adding, "The use of some emergency drugs heightens risk, as does the use of certain anesthetic techniques."
About 90% of all accidental awareness incidents in the study involved the use of muscle-relaxant drugs, researchers say. They believe patients were given an inappropriate balance of medication. Seventeen of the 300 cases involved medication errors.
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Researchers recommend that hospitals prevent such episodes by using simple anesthesia checklists before every surgery.
"For the vast majority it should be reassuring that patients report awareness so infrequently. However for a small number of patients this can be a highly distressing experience," says lead author Tim Cook. He adds, "I hope this report will ensure anesthetists pay even greater attention to preventing episodes of awareness" (Saul, The Independent, 9/10; Mundasad, BBC News, 9/10).
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