Jan

19

Research by Professor Michael Wang

January 19, 2008

Take a look at this invaluable research by Professor Michael Wang regarding the definition, frequency, and consequences of ‘awareness’ experiences,plus excellent advice for professionals on how to treat patients in the aftermath:

Learning in your sleep? The psychological effects of awareness
Prof. Michael Wang, Clinical Psychology Unit,
University of Leicester

Summary
Episodes of full awareness with explicit recall are more common than many anaesthetists realise (1 in 500 operations1,2,3). Awareness with full recall is usually distressing and
associated with acute PTSD reactions4,22. The common reason for failure on the part of anaesthetists to identify intra-operative awareness is the paralyzing effect of muscle relaxants;
contrary to traditional belief, autonomic and haemodynamic variables are unreliable indicators of wakefulness5. Studies conducted in Hull have made use of the isolated forearm
technique9,15,16 to determine levels of consciousness during GA, which allows communication despite the muscle paralysis. Often patients will demonstrate high levels of intra-
operative consciousness but without post-operative explicit recall. This is because many anaesthetic drugs impair the encoding phase of memory. It is likely that previous studies
demonstrating intra-operative implicit (unconscious) learning have involved learning episodes during such states. Implicit memory can be demonstrated in states of intra-operative
wakefulness without explicit recall, including implicit emotional memory6-14. Studies in Hull have also investigated benzodiazepine sedation as another clinical circumstance in which
there may be dissociation between implicit and explicit recall. There is an intriguing literature in which patients have developed psychological disturbance following operations with GA
in which the patient has no explicit recall, but the nature of the disturbance is indicative of inadequate anaesthesia. Experimental studies that attempt to investigate the mechanisms by
which this may occur are reviewed.

Outline
1.Effects of traumatic awareness with full recall
2.Intra-operative/anaesthetic psychological processing
3.Evidence of Implicit Emotional Memory effects

Post-Traumatic Stress Disorder
 Life threatening experience beyond normal range
 High levels of autonomic arousal/chronic anxiety
 Re-experiencing of traumatic event
 Avoidance of trauma-related cues and/or psychic numbing

Specific aspects of PTSD following Anaesthetic Awareness
 Nightmares, night terrors, often related to paralysis
 Insomnia
 Phobic avoidance of hospital/medical settings and personnel
 Loss of trust in establishment figures
 Relationship difficulties
(in addition to panic attacks, agoraphobia, depression)

The Levinson fabricated anaesthetic crisis study12

Positive Suggestion Studies13,14: randomised, double-blind controlled trials
 About 20 published studies so far
 2:1 ratio of significant versus non-significant difference outcome
 outcome measures include: days to discharge, analgesic use, post-op infection, post-op pain
Failure to replicate
 Impact of volatile agents
 Monitoring

Levels of Consciousness
 full consciousness with full recall
 full consciousness with no explicit recall
 unconsciousness with implicit recall
 unconsciousness with no recall

Explicit Memory
 recall of circumstances of original learning experience
 change in behaviour or knowledge as a result
 e.g. this talk
Implicit Memory
 no recall of original learning experience
 change in behaviour or knowledge
 e.g. subliminal stimuli, riding a bicycle

Detection of Consciousness1-4

 Many anaesthetists believe autonomic indices provide reliable warning of wakefulness, but empirical studies show this to be false5
 Most anaesthetists grossly underestimate the incidence of awareness26
 Many may underestimate the psychological impact of awareness
 EEG power and evoked potential parameters can be helpful but not widely available

Implicit Learning: Word Priming
 Word association: word pairs, category generation
 Word stem completion: “car-ton”
 Homophones: “dinner at eight”

Implicit Memory Probes17,18,23,24
Intra-operatively:
 green - pear
 sharp - lemon
 sour - gooseberry
Post-operative probes:
 say first 5 fruits
 word pair association
 word list with distractors
 hypnosis

Levels of Consciousness
 full consciousness with full recall
 full consciousness with no explicit recall
 unconsciousness with implicit recall
 unconsciousness with no recall

Implicit Emotional Memory
 Case reports of phobias, panic attacks & nightmares following an operation6-12
 evidence of anaesthetic lightness during operation, but patient has no conscious knowledge of this

Anaesthetic Lightening Study (Wang, Logan & Russell 1998)25
 Prospective double blind study suggestive that wakefulness may be associated with post-operative psychopathology; however
 Quasi-experimental methodology cannot prove causal link

Colonoscopy Study (Woodruff & Wang; in progress)

Summary
 Awareness with explicit recall occurs in about 1:500 operations (Liu et al., 1991; Ranta et al., 1997; Sebel et al., 2004)
 Intra-operative wakefulness without explicit recall is much more common and can be detected using the IFT
 Implicit priming effects are probably a result of episodes of intra-operative wakefulness without explicit recall
 Studies conducted in Hull provide evidence of implicit emotional memory following intra-operative wakefulness without explicit recall

REFERENCES
1. Lui, WHD, Thorp, TAS, Graham, SG, Aitkenhead, AR. Incidence of awareness with recall during general anaesthesia. Anaesthesia, 1991, 46, 435-437.
2. Ranta, S., Laurila, R., Saario, J., Ali-Melkkila, T., Hynynen, M. Awareness with recall during general anesthesia: incidence and risk factors. Anesthesia and Analgesia, 1998, 86, 1084-
1089.
3. Sebel, P, Bowdle, TA, Ghoneim, MM, Rampil, IJ, Padilla, RE, Tong, JG, Domino, K. The incidence of awareness during anesthesia: a multicenter United States study. Anesthesia &
Analgesia 2004; 99:833-9
4. MacLeod, A., Maycock, E. Awareness during anaesthesia and post traumatic stress disorder. Anaesthesia and Intensive Care, 1992, 20, 378-382.
5. Moerman N, Bonke B, Oosting J. Awareness and recall during general anaesthesia. Anaesthesiology 1993; 79: 454-464.
6. Meyer, B., Blacher, R. A traumatic neurotic reaction induced by succinylcholine chloride. New York Journal of Medicine, 1961, 61, 1255-1261.
7. Bergstrom, H., Bernstein, K. Psychic reactions after analgesia with nitrous oxide for caesarean section. Lancet, 1968, 2, 541-542.
8. Blacher, R. On awakening paralysed during surgery: a syndrome of traumatic neurosis. Journal of the American Medical Association, 1975, 234, 67-68
9. Tunstall, M. Anaesthesia for obstetric operations. In Clinics in Obstetrics and Gynaecology 7, Number 3, (ed. I. MacGillivray)1980, chapter 11. WB Saunders: London.
10. Howard, J. Incidents of auditory perception during anaesthesia with traumatic sequelae. The Medical Journal of Australia, 1987,146, 44-46.
11. Tinnin, L. Conscious forgetting and subconscious remembering of pain. Journal of Clinical Ethics, 1994, 5, 151-152.
12. Levinson B. States of awareness under general anaesthesia. Br J Anaesth 1965; 37: 544-546.
13. Evans C, Richardson PH. Improved recovery and reduced postoperative stay after therapeutic suggestions during general anaesthesia. Lancet 1988; 2: 491-492.
14. Merikle PM, Danemann M. Memory for events during anaesthesia: A meta-analysis. In: Bonke B, Bovill JG, Moerman N, eds. Memory and Awareness in Anaesthesia. Assen: Van
Gorcum & Comp. B.V, 1996: 108-121
15. Russell IF. Conscious awareness during general anaesthesia: relevance of autonomic signs and isolated arm movements as guides to depth of anaesthesia. In : Jones JG ed. Bailliere’s
Clinical Anaesthesia, vol. 3, no. 3: Depth of Anaesthesia. London: Bailliere Tindall, 1989: 511-532.
16. Wang M, Russell IF, Charlton PFC, Conlon J. An experimental simulation of anaesthetic awareness and validation of the isolated forearm technique. In: Sebel PS, Bonke B, Winograd E,
eds. Memory and Awareness in Anaesthesia. Englewood Cliffs, NJ: Prentice Hall, 1993: 434-446.
17. Russell IF, Wang M. Absence of memory for intraoperative information during surgery under adequate general anaesthesia. Br J Anaesth 1997; 78: 3-9.
18. Charlton PFC, Wang M, Russell IF. Implicit and explicit memory for word stimuli presented during general anaesthesia without neuromuscular blockade. In: Sebel PS, Bonke B,
Winograd E, eds. Memory and Awareness in Anaesthesia. Englewood Cliffs, NJ: Prentice Hall, 1993: 64-73.
19. Russell, IF. Midazolam-Alfentanil: an anaesthetic? British Journal of Anaesthesia
20. Wang, M. Learning, memory and awareness during general anaesthesia. in Adams, A and Cashman, J. (eds.)Recent Advances in Anaesthesia and Analgesia Volume 1998, 20 p83-106
Churchill-Livingstone, Edinburgh
21. Wang, M. Inadequate anaesthesia as a cause of psychopathology [invited editorial] Royal College of Anaesthetists Newsletter 1998, 40, 20-22
22. Wang, M. The psychological consequences of awareness during surgery. In Jordan, C., Vaughan, D.J.A., Newton, D.E.F. (eds.) Memory and Awareness in Anaesthesia IV pp315-324
Imperial College Press, London 1999
23. Russell , I. and Wang, M. A randomised double blind investigation of post-operative memory for intra-operative information presented during total intravenous anaesthesia
controlled by the isolated forearm technique. In Jordan, C., Vaughan, D.J.A., Newton, D.E.F. (eds.) Memory and Awareness in Anaesthesia IV pp315-324 Imperial College Press, London
1999
24. Russell, I. and Wang, M. Absence of memory for intraoperative information during surgery with total intravenous anaesthesia British Journal of Anaesthesia 2001, 86, 196-202
25. Wang, M. The psychological consequences of explicit and implicit memories of events during surgery. In Ghoneim, M. (ed.) Awareness during Anesthesia Butterworth-Heinemann,
Woburn USA 2001
26. Myles, P., Leslie, K., McNeil, J., Forbes, A., Chan, M. Bispectral index monitoring to prevent awareness during anaesthesia: the B-Aware randomised controlled trial. The Lancet
2004; 363:1757-63


SIMPLE GUIDELINES FOR THE MANAGEMENT OF THE POST-AWARE PATIENT

  1. Don’t avoid the patient! Take a witness with you
  2. Obtain a detailed account from the patient: Listen carefully, show concern and a desire to be clear about what the patient has experienced
  3. Make it clear that you believe the patient’s account of events
  4. Express regret that this has occurred: this does not constitute an admission of liability
  5. As accurate an account of the cause of the awareness should be given to the patient as early as possible
  6. Check for psychological disturbance (flashbacks, nightmares, anxiety, depression) within first 24 hours – refer to psychologist or psychiatrist if problems
  7. Follow-up within 2 weeks of operation

NB

  • Blatant fabrication is extremely rare
  • Patient may have experienced an unpleasant dream not involving specific surgical events
  • Events during the immediate post-operative or pre-operative period may be incorrectly attributed as intra-operative: Confirm these events with other theatre or recovery staff
  • Confusion should be addressed gently, with care and understanding

REFERENCES

Aitkenhead, AR Editorial: Awareness during anaesthesia - what should the patient be told? Anaesthesia 1990, 45, 351-352

Wang, M. The psychological consequences of explicit and implicit memories of events during surgery
In Ghoneim, M. (ed.) Awareness during Anesthesia 2001; Butterworth-Heinemann, Woburn USA

M. Wang
16.11.04