A synthesis of the Australian Patient Safety Foundation Anesthesia Incident Monitoring Study, the American Society of Anesthesiologists Closed Claims Project, and the American Association of Nurse Anesthetists Closed Claims Study.

The study of anesthesia risk is fraught with methodological challenges and the epidemiological uncertainty peculiar to anesthesia: the true frequency of anesthetic mortality is unknown. If anesthesia mortality is as rare as 1 in 200,000 cases, the sample needed to study this phenomenon would be enormous. Existing studies provide insights to the genesis of damaging events and adverse outcomes in anesthesia. We examined research design, methodology, and findings to date in 3 studies of anesthesia risk. Limitations include self-report by providers in the Australian study and the retrospective nature of closed claims research in American studies. Respiratory events were the largest class of injury in all 3 studies; substandard care frequently was involved. Australian investigators noted a high rate of human error and equipment issues. American physician investigators found that death or brain damage occurred in 85% of respiratory cases, 72% of which were deemed preventable. Nurse anesthetist investigators had similar findings for respiratory claims. Patient acuity and procedure complexity may be less significant contributory factors to anesthesia risk than are provider vigilance and clinical decision making. Prospective multicenter studies conducted politically may be the only type of research that definitively addresses the myriad issues in anesthesia risk research.