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Awareness with recall following general anesthesia

Michael Avidan, MD
George A Mashour, MD, PhD
Section Editor
Girish P Joshi, MB, BS, MD, FFARCSI
Deputy Editor
Nancy A Nussmeier, MD, FAHA


The phrase awareness with recall (AWR) refers to both intraoperative consciousness and explicit recall of intraoperative events. The most important contributing factor for AWR is underdosing of anesthetic agents relative to the patient's specific requirements. Although the incidence of AWR may be reduced with preventive measures, it may not be eradicated completely. Thus, all patients undergoing general anesthesia should be informed that AWR is rare, but can occur.

This topic will discuss the risk factors, sequelae, and prevention of AWR after general anesthesia.


Awareness experiences range from isolated auditory perceptions to reports of a patient being fully awake, immobilized, and in pain. Incidence of AWR varies widely due to methodological differences in postoperative assessment of awareness and differences in anesthetic practice [1]. Although the most common outcome measured is postoperative recall for the awareness event, intraoperative consciousness and explicit recall of intraoperative events may be dissociated from each other. In one study, only one in four patients with evidence of intraoperative awareness had explicit postoperative recall of the event [2].

Large, prospective, multicenter studies of awareness with recall (AWR) in adult patients undergoing surgery with general anesthesia have reported an incidence of 1 to 2 cases/1000 in North America and Europe [3-8]. Studies with prospective patient interviews that specifically inquire about awareness have noted an incidence of 0.1 to 0.2 percent in the general population and approximately 1 percent in high-risk populations [3,4,7,8]. The fifth National Audit Project (NAP-5) in the United Kingdom was a very large retrospective study that did not include patient interviews; the reported incidence was 1 in 15,000 to 1 in 19,000 [9,10]. This probably reflects under-detection since patients were not interviewed to assess AWR [11].

In children, the incidence of AWR after general anesthesia is slightly higher, between 0.2 to 1.2 percent [12]. Pooled data from a combined sample of five cohort studies involving 4486 pediatric anesthetics revealed 33 cases of awareness. Assessing the presence of AWR in children, however, poses a number of challenges related to developmental factors and the accuracy of postoperative interviews [13,14].

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Literature review current through: Nov 2017. | This topic last updated: Dec 13, 2016.
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