Anesthesia awareness

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Awareness under anesthesia, also referred to as intraoperative awareness or accidental awareness during general anesthesia (AAGA), is a rare complication of general anesthesia where patients regain varying levels of consciousness during their surgical procedures. While anesthesia awareness is possible without resulting in any long-term memory of the experience, it is also possible for victims to have awareness with explicit recall, where they can remember the events related to their surgery (intraoperative awareness with explicit recall).^[1]

Intraoperative awareness with explicit recall is an infrequent condition with potentially devastating psychological consequences.^[2] While it has gained popular recognition in media, research shows that it only occurs at an incidence rate of 0.1–0.2%. Patients report a variety of experiences, ranging from vague, dreamlike states to being fully awake, immobilized, and in pain from the surgery. Intraoperative awareness is usually caused by the delivery of inadequate anesthetics relative to the patient's requirements. Risk factors can be anesthetic (e.g., use of neuromuscular blockade drugs, use of intravenous anesthetics, technical/mechanical errors), surgical (e.g., cardiac surgery, trauma/emergency, C-sections), or patient-related (e.g., reduced cardiovascular reserve, history of substance use, history of awareness under anesthesia).

Currently, the mechanism behind consciousness and memory under anesthesia is unknown, although there are many working hypotheses. However, intraoperative monitoring of anesthetic level with bispectral index (BIS) or end-tidal anesthetic concentration (ETAC) may help to reduce the incidence of intraoperative awareness, although clinical trials have yet to show a decreased incidence of AAGA with the BIS monitor.^[3]

There are also many preventative techniques considered for high-risk patients, such as pre-medicating with benzodiazepines, avoiding complete muscle paralysis, and managing patients' expectations. Diagnosis is made postoperatively by asking patients about potential awareness episodes and can be aided by the modified Brice interview questionnaire. A common but devastating complication of intraoperative awareness with recall is the development of post-traumatic stress disorder (PTSD) from the events experienced during surgery. Prompt diagnosis and referral to counseling and psychiatric treatment are crucial to the treatment of intraoperative awareness and the prevention of PTSD.