The incidence of accidental awareness under general anesthesia is commonly cited as approximately 0.2% which is probably an overestimation. According to other sources, the incidence of traumatic intraoperative recall associated with pain is less than 0.03%. The American Society of Anesthesiologists Closed Claims database states that claims associated with recall during anesthesia constitute 1.5% of claims. An increased relative risk for recall is seen in certain types of surgery, including cardiac surgery, cesarean delivery, and trauma surgery; this most likely represents intentional light anesthesia during varying levels of surgical stimulation. The Anesthesia Patient Safety Foundation recommends maintaining an inhaled anesthetic concentration of 0.7 MAC whenever a neuromuscular blocking agent is given to avoid intraoperative awareness, and if this is not possible, to use a processed electroencephalogram (EEG) monitor such as bispectral index to help monitor and assure adequate depth of anesthesia.

Bispectral index monitoring can be useful, but the application of these monitors during trauma resuscitation might not be easily accomplished. Patients with a bispectral index value of 50 were able to respond to verbal commands less than 10% of the time.

References

• APSF Committee on Technology. The APSF Committee on Technology. APSF endorsed statement on revising recommendations for patient monitoring during anesthesia. APSF Newsl. 2022;37:7-8.
• Johansen JW. Update on bispectral index monitoring. Best Pract Res Clin Anaesthesiol. 2006;20:81-99.
• Rampil IJ. Monitoring depth of anesthesia. Curr Opin Anaesthesiol. 2001;14:649-653.