Awareness during Anaesthesia : Incident or Mismanagement ?

1. Awareness during Anaesthesia : Incident or Mismanagement ? Dr. Alain F. Kalmar, MD, PhD Dep. Of Anaesthesia University Medical Center Groningen The Netherlands

2. Incident or Mismanagement ? • Complex interaction between - Pharmacology (PK/PD) - Patient characteristics & genetics - Surgical events • Many unknown variables may increase risk • Evolution to psychological disorders ~ our policy  Inevitable event or anesthetic mismanagement ?

3. Action and receptors and … AROUSAL NOXIOUS STIMULUS propofol barbiturates benzodiazepines inhalational an. opiates AROUSAL Local an.

4. Definitions? “consciousness” is NOT equal to “awareness” “physiological condition” versus “failed drug effect”

5. Types of Awareness Reports • True Awareness with Recall and pain • True Awareness with Recall but without pain • Adequate response on demand without recall • Opening of Eyes/Movement without Recall • “Memories” • Conscious Sedation (Inform patient !) • Implicit (“Unconscious”) Learning • Diagnose with complex psychological questionnaires • Vivid dreaming • Triggered by recovery experience? • (Unwise to do sedation without witnesses)

6. Movement ≠ awake Immobile ≠ unconscious Responsive ≠ aware Amnesia ≠ unresponsive

7. Working and long-term memory ( Bailey AR et al., Anesthesia 1997, 52, 460 - 476. ) Central EncodingexecutiveStimulus Long termPhonologicalVisuospatialmemory loop sketchpadWorkingmemoryRetrieval RespondingForgetting

8. Declarative and nondeclarative memory. ( Bailey AR et al., Anesthesia 1997, 52, 460 - 476. ) outside world declarative working nondeclarative memory memory memory explicit implicit episodic semantic skills and priming procedures events or general or specific knowing how increased ability episodes within knowledge to identify a the subject’s life stimulus as a result of recent presentation

9. Where did it all start? • Awareness during anaesthesia became a problem after muscle relaxants was introduced in the 1940’s • Balanced anaesthesia: • Immobility Curare • Haemodynamics Inotropica, vasodilators, B-Blokkers • Analgesia Opioids • Hypnosis Hypnotics • Smaller amount of general anaesthetics were needed. • High Opioids / low hypnotics methods • Changing attitude in patients

10. Cause of awarenessStudy pitfalls • Retrospective • Many studies lack information on ET gas concentration or IV drug concentrations. Hard to compare anaesthetic techniques and causes • The use of neuromuscular blockers has an important role and are not always reported • Definition • Timing of the screening interview is crucial • Many studies only interview patients once within 24 hours after surgery • Underestimation of incidence is probable

11. Causes of Awareness(closed claims analysis) • N = 4183 closed claims (retrospective + selection bias) - aspirationpneumonia 2.4 %- awareness 1.9 % (=80 cases) - burns 1.9 % • Possible (retrospective) causesforawareness: - N2O - relaxanttechnique - hypotension (withdecreasedamount of hypnotics) - inadequate doses of drugs - obesity - difficultintubation - vaporizerleaks - failure to turn on the vaporizer - noobvious factor (Patientsensitivity???) ( Domino et al. Anesthesiology 1999, 90, 1053 - 61)

12. Incidence of explicit recall Remember being awake and recall things that were said or done during operation Year Hutchinson 1960 1.2% 656 Harris 1971 1.6% 120 McKenna 1973 1.5% 200 Wilson 1975 0.8% 490 Flier 1986 1.4% 140 Liu 1991 0.2% 1000 Nordström 1997 0.2% 1000 Ranta 1998 0.4 - 0.7% 2612 Myles 2000 0.11% 10811 Sandin 2000 0.15% 11785 Incidence Number of patients The first half is not relevant today because the anaesthesia technique has changed a lot. With kind permission from Dr Rolf Sandin, Kalmar, Sweden

13. How damaging is Awareness? • Global incidence 0.1-0.3% • 35-70/year in UMCG • 65% of patients do not tell the anesthesiologist • Moerman et al. Anesthesiology, 1993 79:454-464 • 50% of patients are concerned about awareness • McCleane and Cooper. Anesthesia, 1990 45:153-5 • Highest risk factor for patient dissatisfaction • Myles et al. Patient satisfaction after anesthesia and surgery . BJA, 2000 84 : 6-10

14. Awareness : patients’ evaluation • Awareness : - auditory perception - sensation of paralysis - anxiety, pain - helplessness - panic >> 70 % : sleep disturbances, dreams, nightmares, flashbacks,… < % : P.T.S.S. ( repititive mightmares, anxiety, irritability, preoccupation with death,…) (ref.: Schwender et al. BJA, 1998, 80, 133-139)(ref.: Domino et al. Anesthesiology 1999, 90, 1053 - 61)

15. Sandin’s study year 2000 • 11785 patients • 1997 - 1999 in 2 hospitals • Patients were interviewed 3 times • Most of patient received Neuromuscular blockers • 18 patients identified with explicit recall • At PACU: 11 of 18 identified • Day 1-3 : 12 of 18 identified • Day 7-14: 17 of 18 had explicit recall • The 18 patient forgot everything, even the interview, but started to remember some details after 21 days, but was not worried at all about it. • 1 of these had experienced awareness before.

16. Sandin’s study year 2000 • So, only halfof cases can be identified with todays advice of 1 interview at PACU discharge • Awareness : consequences: • More Pain and chronic pain • Panic • Post Traumatic Stress Disorder

17. Explicit recall - long term effects Fear & Panic Pain Late mental effects Evans 1987 78% 41% ? n=27 Moerman1993 92% 39% 70% n=26 Schwender1998 50% 24% 49% n=45 Domino 1999 11% 21% 84% n=79 (closed claims) Sandin et al. 64% n= 9-18 (prospective) 43% 21% With kind permission from Dr Rolf Sandin, Kalmar, Sweden

18. Sandin’s study • There is only 21% late mental effects. But, that is after a few weeks • 3 weeks after the awareness all 18 were happy. • Interviews then happened 2 years later • 9 of the 18 could then be included • 6 refused interview: 2 wanted to avoid anything that had to do with anaesthesia. • 2 could not be localised • 1 was dead • So, what about the 9 that co-operated

19. Sandin’s study • The last 9 that were located: • 4 had PTSD ( Post-Traumatic Stress Disorder) • 3 had less severe problems • 2 had no mental problems • So, when you follow up over time, the result is different

20. Awareness : patients’ treatment • Explicit recall must be taken serious • Believe the patients experience • Early referral to psychiatrists • Repeated follow-ups • In Sandin’s case, the less severe cases turned out to be the worst and detected latest • Memory for intraoperative events may improve for more than 10 days • So, what can be done to prevent this?

21. Prevention • Do not deny awareness risks? • Seems that patient information reduces the risk of neurotic symptoms afterwards, because the patient is “prepared” mentally that this could happen. • A little bit of psychology seems to help to limit post awareness trauma • Interview of patients? • 4 QUESTIONS as a standard routine (educate nurses) • Did you sleep well? • Last memorybeforefallingasleep? • First memorywhenwaking up? • Do yourememberanythingfrom in between these twomoments? • Do not deny your patients story? • (ref.: Schwender et al. BJA, 1998, 80, 133-139)(ref.: Domino et al. Anesthesiology 1999, 90, 1053 - 61)

22. Considerate Conduct “Anesthetized (butalsoawake) patientstend to sensor whattheyhear, retainingcommentstheyconsider important. Commoncategories of comments: • the ‘fat lady syndrome’, in which doctors makederogatoryappraisals of a patient’sappearance. • the ‘dirtballphenomen’, in whichpatients are treated to remarksderidingtheirworth.” • The ‘bad message’ effect, in whichpatients are focussed more onnegativethanonreassuringmessages (Henry Bennett as quoted in Hippocrates, 1997)

23. PreventionMore Benzodiazepines? Lancet 2000; 355:707 • More Benzodiazepines? • No randomised ctr. Studies • In the Sandin incidence paper similar incidence with/without use of benzodiazepines. • No strong evidence… • the practice of giving benzodiazepines as a prevention • = pure empirical conviction

24. “Valley of no anaesthesia” ???? Maybe... Butnoevidence Induction with propofol bolus Sevoflurane maintenance “Depth of anaesthesia” Valley of no anaesthesia

25. Avoid TIVA? • Errando et al: Awareness with recall during general anaesthesia: a prospective evaluation of 4001 patients, BJA 2008;101;7402 • 1.1% awareness with TIVA • 0.6% with inhalation • Sandin and Myles study: No sign. difference between patients with TIVA vs inhaled anaesthesia

26. Explicit recall after TIVA • Incidence Sandin 1993 Br J Anaesth Retrospective study 5 / 1727 Nordström 1997 Acta Anaesthesiol Scand • Prospective study: Interview d1 + d7 (50%): 2 / 1000 Sandin 2000 The Lancet Prospective study: Interview d1-3 + d7-14: 0 / 284 0.2% With kind permission from Dr Rolf Sandin, Kalmar, Sweden

27. PreventionEnd-tidal gas monitoring? • Avidan et al NEJM 2011 • High risk population • Power analysis OK • Comparing BIS monitoring with MAC >0.7 concept • RESULTS: See further at the prevention section

28. PreventionMeasure Vital Signs? • Monitor Vital Signs (BP, Heart rate) only? • vital signs reflect balance between OS and PS and not hypnosis • The degree of depression of the Central Nervous System may not be totally correlated to the degree of depression of the Cardio-Vascular System for a specific patient at each moment. This will be true also with patients without Cardio active medication. • Many cases of intraoperative recall do not signal with hemodynamic changes (Domino 1999) • So, basically Vital Signs areInsufficient as an indication of awareness

29. EEG On Line processing

30. PreventionValue of neuro-physiological monitoring? • General population : Power analysis : 47022 patients needed to show reduction 0,2%  0,1% of awareness! • B-Aware trial (Myles P, The Lancet, 2004): • Selection of high risk patients • Multi centre study with sufficient inclusions • Results: The use of BIS reduces the incidence of explicit awareness by 82% in a high risk population. (p<0.002)

31. PreventionNeuro-physiological monitoring IN GENERAL population? (Sandin et al: ActaAnaesthScand 2004: 48:20-6) • Comparable results in a former retrospective Scandinavian trial (Sandin et al ) in the general population. (Retrospective control) • SAFE 2 trial : The use of BIS reduces the incidence of explicit awareness by 78% in a general population. (p<0.05) 0,03% 0,17%

32. PreventionNeuro-physiological monitoring during inhaled anaesthesia in high risk patients? (Avidan) • Avidan et al. NEJM 2011: • During inhaled sevofurane concentration, a strategy to keep sevo ET% > 0.7 MAC (+ setting alarms accurately + checklists and education) is equally effective to avoid awareness in a high risk population compared to BIS guided anaesthesia. • BIS guided group 7/2861 (0.24%) compared to ETAC group 2/2852 (0.07%) but not statistically significant • No mortality difference postoperatively • Questions: • Overdosing for some in ETAC harmful? • What before intubation?

33. Final CONCLUSIONS 1 • Awareness is a problem for all anesthetists • Awareness is not always a proof of medical error

34. Final CONCLUSIONS 2 • The consequences are worsethan we think

35. Final CONCLUSIONS 3 • BIS is the only monitor that has evidence to support a reduction in awareness in a high risk populationwith mixed anaesthesia techniques. • WhenSevo>0.7 MAC in high risk population the incidence of awareness = BIS monitoredapproachwithlower MAC accepted. • General population: probablycomparable effect butlesspowerfulevidence to support this

36. Final CONCLUSIONS 4 •  USE BIS when you feel uncertain about the hypnotic state of the patient.

37. Final CONCLUSIONS 5 • Try to detect eventual cases of awareness • Immediately inform the patient about the meaning of these experiences and show empathy.

38. Questions?