Frequency of Anesthesia Awareness
Mashour GA, Wang LYJ, Turner CR, Vandervest JC, Shanks A, Tremper KK.
A retrospective study of intraoperative awareness with methodological implications.
Anesth Analg 108, (2), 521-536, 2009.
Standard evaluations are done postoperatively at the authors’ institution and information on awareness is listed. Regardless of the anesthetic type, evaluations are completed. This study is a chart review of 65,061 patients receiving general anesthesia and 51,417 receiving other types of anesthesia. The incidence rate of awareness from 44,006 patients receiving general anesthesia was 0.023% or 1/4401 patients. The incidence among 22,885 patients who had other types of anesthesia was 0.03% of 1/3269 patients.
Pollard RJ, Coyle JP, Gilbert RL, Beck JE.
Intraoperative awareness in a regional medical system: A review of 3 years’ data.
Anesthesiology 106: 269-74, 2007.
In this study 1 out of 14,560 (.007%) patients experienced awareness, this is approximately 20 times less than the incidence from other major studies. One possible explanation for this different finding was that patients were not asked as directly about awareness as they were in other studies. Other studies have found that patients may not choose to discuss or recall that they were aware unless they are asked directly about it on more than one occasion.
Sebel PS, Bowdle TA, Ghoneim MM, et al.
The incidence of awareness during anesthesia: A multicenter United States study.
Anesth Analg 99: 833-9, 2004.
This is one of the first large-scale studies examining the incidence of awareness in the United States. In this study, researchers reported that the incidence of awareness in seven academic medical centers throughout the United States is comparable to those of other countries. Out of 19, 575 patients, 25 patients were identified as experiencing awareness (e.g. incidence of 0.13%).
Sandin RH, Enlund G, Samuelsson P, Lennmarken C.
Awareness during anaesthesia: A prospective case study.
Lancet 355: 707-11, 2000.
In this study of 11,785 patients awareness occurred in 0.15% or (1 in 655). This study found that multiple interviews after the anesthetic may be necessary to discover that awareness occurred. It was also discovered that awareness occurred with greater frequency in patients where muscle relaxant (paralyzing) medications were used as part of the anesthetic.