Learning objectives

• Describe the implications and risk factors of awareness during anesthesia
• Prevent awareness during anesthesia
• Diagnose and manage patients who experienced awareness during anesthesia

Definition & mechanisms

• Rare but severe complication of anesthetic care
• Also referred to as “accidental awareness during general anesthesia” (AAGA)
• Mostly occurs during induction and emergence
• Can range from only auditory or tactile awareness to being fully awake with paralysis and pain
• Traumatic experience with possibly severe long-term effects (post-traumatic stress disorder)

Risk factors

• Neuromuscular blocking
• Female gender
• Pregnancy
• Cardiothoracic patients
• Obesity
• Total intravenous anesthesia
• Trauma & emergency surgery
• Ketamine, etomidate, and thiopental use
• Difficult intubation
• History of AAGA
• Chronic drug use
• Lack of monitoring

Psychological assessment and diagnosis

• Acute stress disorder (ASD): Occurs shortly after traumatic event (3 days to 1 month)
  • Diagnosis: at least 9 of the following symptoms:
    • Recurring, uncontrollable, and intrusive distressing memories of the event
    • Recurring nightmares of the event
    • Flashbacks of the event
    • Intense psychological or physical distress when reminded of the event 
    • Persistent inability to experience positive emotions 
    • Altered sense of reality 
    • Memory loss for an important part of the traumatic event
    • Efforts to avoid distressing memories, thoughts, or feelings associated with the event
    • Efforts to avoid external reminders associated with the event
    • Disturbed sleep
    • Irritability or angry outbursts
    • Hypervigilance
    • Concentration difficulties
    • Exaggerated startle response
• Post-traumatic stress disorder (PTSD): Diagnosed when symptoms persist for more than 1 month after the traumatic event

Prevention

• Check equipment and medications
• Depth of anesthesia monitoring (EEG is superior to BIS)
• Avoid or minimize the use of neuromuscular blocking agents
• Monitor neuromuscular block if neuromuscular blocking is necessary
• Use target-controlled infusion for total IV anesthesia

Management

Management is based on treating psychological symptoms:

• Early face-to-face postoperative meeting with the patient and consultation with a psychiatrist or psychologist
• Psychological interventions (e.g, cognitive behavioral therapy)
• Antidepressants
• Benzodiazepines for acute anxiety (beware of potential abuse)
• Antipsychotics may be helpful in some patients

Suggested reading

• Kim MC, Fricchione GL, Akeju O. Accidental awareness under general anaesthesia: Incidence, risk factors, and psychological management. BJA Education. 2021;21(4):154-61.
• Mashour GA, Avidan MS. Intraoperative awareness: controversies and non-controversies. Br J Anaesth. 2015;115 Suppl 1:i20-i26. 
• Tasbihgou SR, Vogels MF, Absalom AR. Accidental awareness during general anaesthesia – a narrative review. Anaesthesia. 2018;73(1):112-22.
• Mashour GA, Orser BA, Avidan MS, Warner DS. Intraoperative Awareness: From Neurobiology to Clinical Practice. Anesthesiology. 2011;114(5):1218-33.

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