Awareness Under Anaesthesia

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Accidental awareness during general anaesthesia (AAGA) is the unintended recall of intraoperative events by patients who received general anaesthesia, occurring in approximately 0.1-0.2% of general surgical cases (1-2 per 1000) but higher in high-risk groups (obstetric, cardiac, emergency). Types: Explicit recall (conscious memory, patient reports awareness), implicit memory (unconscious memory, affects behavior without conscious recollection). Risk factors: Female gender, obesity, anaesthetic technique (TIVA more than volatile, rapid sequence, muscle relaxants preventing movement), emergency surgery, obstetric surgery (reduced MAC, avoidance of opioids before delivery), cardiac surgery, light anaesthesia (insufficient dosing, equipment failure), difficult airway (prolonged attempts with interrupted anaesthesia). Consequences: Immediate (fear, helplessness, pain, paralysis), short-term (anxiety, sleep disturbance), long-term (PTSD in 30-50%, severe psychological trauma, avoidance of future medical care). Prevention: Adequate depth of anaesthesia (MAC 0.7-1.0 volatile or BIS 40-60), careful TIVA dosing with pumps and monitoring, depth of anaesthesia monitoring (BIS, entropy), end-tidal volatile monitoring (ETAG 0.7-1.3 MAC), train-of-four monitoring (ensure paralysis complete—no movement), appropriate analgesia (opioids reduce MAC), psychological preparation (anxious patients at higher risk). Detection: Depth monitoring (BIS <60 awareness unlikely, >80 awareness possible, 40-60 optimal); processed EEG (BIS, SE, RE); lack of MAC/end-tidal gas alarm; equipment checks (vaporizer filled, delivering gas). Response to suspected awareness: Maintain patient dignity, acknowledge experience, empathic listening, early referral to psychology/psychiatry, detailed documentation, follow-up support, debriefing for theatre team, incident reporting. BIS monitoring: Bispectral index processes EEG signals to assess depth; 100 = awake, 60 = general anaesthesia, 40 = deep, 0 = isoelectric; recommended for TIVA, high-risk patients, long cases; controversies (not 100% sensitive, affected by some drugs and conditions); algorithm not fully disclosed. Obstetric considerations: Lower MAC in pregnancy, opioid avoidance until delivery (fetal depression), higher awareness risk; BIS monitoring recommended; clear documentation of technique and patient counseling. Indigenous considerations: Cultural communication about awareness important; follow-up may be challenging in remote areas; ensure support structures in place. [1-10]