“The Incidence of Awareness During Anesthesia: A Multicenter United States Study”, Peter S. Sebel, T. Andrew Bowdle, Mohamed M. Ghoneim, Ira J. Rampil, Roger E. Padilla, Tong Joo Gan, Karen B. Domino2004-09 (anesthesia)⁠:

Awareness with recall after general anesthesia is an infrequent, but well described, phenomenon that may result in post-traumatic stress disorder. There are no recent data on the incidence of this complication in the United States. We, therefore, undertook a prospective study to determine the incidence of awareness with recall during general anesthesia in the United States.

This is a prospective, nonrandomized descriptive cohort study that was conducted at 7 academic medical centers in the United States. Patients scheduled for surgery under general anesthesia were interviewed in the postoperative recovery room and at least a week after anesthesia and surgery by using a structured interview. Data from 19,575 patients are presented.

A total of 25 awareness cases were identified (0.13% incidence). These occurred at a rate of 1–2 cases per 1,000 patients at each site. Awareness was associated with increased ASA physical status (odds ratio, 2.41; 95% confidence interval, 1.04–5.60 for ASA status III–V compared with ASA status I–II). Age and sex did not influence the incidence of awareness.

There were 46 additional cases (0.24%) of possible awareness and 1,183 cases (6.04%) of possible intraoperative dreaming.

The incidence of awareness during general anesthesia with recall in the United States is comparable to that described in other countries. Assuming that ~20 million anesthetics are administered in the United States annually, we can expect ~26,000 cases to occur each year.