Anaes · Depth of anaesthesia & awareness
Accidental awareness under general anaesthesia: NAP5 and prevention
Also known as Accidental awareness under general anaesthesia · AAGA · Intraoperative awareness · Anaesthesia awareness · NAP5 awareness · Awareness with recall
Exam-pass AAGA topic built on NAP5: incidence, risk groups (TIVA, NMB, obstetrics, cardiac, emergency), end-tidal agent alarms, processed-EEG when agent unmeasured, Brice interview, compassionate response, and B-Aware/BAG-RECALL context for ANZCA Final and FRCA.
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Red flags
- TIVA without a continuous delivery check and depth monitor is the modern high-risk setup for AAGA.
- Neuromuscular blockade removes movement as a warning and confounds some EEG indices — avoid unnecessary paralysis.
- Believe every report of voices, paralysis, or pain under GA — use Brice questions, apologise, offer psychology, report the incident.
- Obstetric GA, cardiac, trauma, and difficult airway are classic high-risk contexts for deliberately light or interrupted anaesthesia.
- Silenced low-agent alarms, empty vaporisers, and mis-programmed TCI pumps create silent sub-anaesthetic delivery.
- A 'surgical-range' BIS/PSI does not exclude awareness — integrate raw EEG and clinical context.
Meet the patient
A patient wakes after a laparotomy done under total intravenous anaesthesia with a neuromuscular blocker and reports hearing voices during the operation while unable to move. That report needs belief, the Brice interview, an apology, and psychological follow-up — the response decides whether this becomes a treated injury or lasting harm.[1][2]
Prevention and response each turn on one question: how did the delivery fail or go unmeasured? (an empty vaporiser, a silenced alarm, a TIVA with no depth monitor), and what made the experience devastating rather than merely unpleasant? (paralysis and helplessness, far more than pain alone).[1]
References6ShowHide
- [1]Pandit JJ, Andrade J, Bogod DG, et al. 5th National Audit Project (NAP5) on accidental awareness during general anaesthesia: summary of main findings and risk factors Br J Anaesth, 2014.PMID 25204697
- [2]Cook TM, Andrade J, Bogod DG, et al. 5th National Audit Project (NAP5) on accidental awareness during general anaesthesia: patient experiences, human factors, sedation, consent, and medicolegal issues Br J Anaesth, 2014.PMID 25204696
- [3]Pandit JJ, Andrade J, Bogod DG, et al. 5th National Audit Project (NAP5) on accidental awareness during general anaesthesia: protocol, methods, and analysis of data Br J Anaesth, 2014.PMID 25204695
- [4]Myles PS, Leslie K, McNeil J, Forbes A, Chan MT Bispectral index monitoring to prevent awareness during anaesthesia: the B-Aware randomised controlled trial Lancet, 2004.PMID 15172773
- [5]Avidan MS, Jacobsohn E, Glick D, et al. Prevention of intraoperative awareness in a high-risk surgical population N Engl J Med, 2011.PMID 21848460
- [6]Messner M, Beese U, Romstöck J, et al. The bispectral index declines during neuromuscular block in fully awake persons Anesth Analg, 2003.PMID 12873942