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Awareness!

Awareness!. Dr James F Peerless April 2013. Objectives. Definition Incidence Risk Factors Monitoring Action Plans NAP5. What is Awareness?. awareness [noun] əˈwɛːnəs knowledge or perception of a situation or fact 1. Awareness under anaesthesia

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Awareness!

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  1. Awareness! Dr James F Peerless April 2013

  2. Objectives • Definition • Incidence • Risk Factors • Monitoring • Action Plans • NAP5

  3. What is Awareness? awareness [noun] əˈwɛːnəs knowledge or perception of a situation or fact1 Awareness under anaesthesia the ability to recall events occurring during general anaesthesia 1Oxford English Dictionary

  4. Types of Awareness • Accidental • Explicit • Spontaneous recall of events, or provoked by questioning • Implicit • No conscious recall, but can affect attitudes and behaviour • Deliberate • e.g. when patients are woken during neurosurgery

  5. Why is it important? • Second commonest pre-operative anxieties expressed by patients • Terrifying experience with long-term complications • Psychological issues • Post-traumatic Stress Disorder • Medico-legal consequences for the anaesthetist

  6. Incidence • Huge variation in reported incidence, mainly due to size of studies and methodology • Studies in 1960s: 7% using N2O • Conscious awareness (no pain) estimated at 1:142-1000 • Explicit recall with pain less common estimated at 1:3000-10000 Heier T, Steen PA. Awareness in anaesthesia: incidence, consequences and prevention. Act Anaesthesiol Scand 1996; 40: 1073–86

  7. Risk Factors

  8. Patient Factors

  9. Anaesthetic Factors

  10. Equipment & Monitoring Factors

  11. Signs of Awareness

  12. Avoiding Awareness • Consider pre-medication • Assurance of >0.8–1 MAC • Adjust MAC for the individual patient • Only use NMBAs when necessary, and in doses to provide sufficient blockade • Consider use of BIS monitoring • Sometimes it just happens – always keep thorough record!

  13. IntraoperativeManagement • Low index of suspicion, especially during ‘at risk’ cases • Deepen anaesthesia immediately • Support hypotension with fluids/vasopressors, not by reducing anaesthetic agent • Consider administering benzodiazepine • No retrograde amnesia but will limit further recall

  14. Postoperative Management • Seek consultant advice • Review the notes • Explain fully to the patient • Offer follow-up including psychiatric support • Reassure the patient that it is unlikely to happen again • Complete a clinical incident form

  15. The Brice Protocol • The Brice interview is used by anaesthetists to detect awareness. • Comprises five questions addressed to the patient after surgery. • Mostly used in research and questions asked at three separate stages: on waking, at 24h, and after two weeks. • What was the last thing you remember before going to sleep? • What is the first thing you remember on waking up? • Can you remember anything in between? • Did you dream during the procedure? • What was the worst thing about your operation? Brice D, Hetherington RR, Utting JE. A simple study of awareness and dreaming during anaesthesia. Br J Anaesth1970:42;535–542

  16. Depth of Anaesthesia Monitors • Specialized equipment has been developed to assist in the assessment of depth of anaesthesia and the state of the central nervous system, based upon EEG and EMG recordings • Opinion of their use is divided, but have recently been endorsed by NICE. www.nice.org.uk/dg6

  17. NICE Recommendations Diagnostics Guidance 6 – Depth of anaesthesia monitors: Bispectral Index (BIS), E-Entropy and Narcotrend-Compact November 2012 • 1.1The use of electroencephalography (EEG)-based depth of anaesthesia monitors is recommendedas an option during any type of general anaesthesiain patients considered at higher risk of adverse outcomes. This includes patients at higher risk of unintended awareness and patients at higher risk of excessively deep anaesthesia. The Bispectral Index (BIS) depth of anaesthesia monitor is therefore recommended as an option in these patients. • 1.2 The use of EEG-based depth of anaesthesia monitors is also recommendedas an optionin all patients receiving total intravenous anaesthesia. The BIS monitor is therefore recommended as an option in these patients. • 1.3 Although there is greater uncertainty of clinical benefit for the E-Entropy and Narcotrend-Compact Mdepth of anaesthesia monitors than for the BIS monitor, the Committee concluded that the E-Entropy and Narcotrend-Compact M monitors[they] are broadly equivalent to BIS. These monitors are therefore recommended as options during any type of general anaesthesia in patients considered at higher risk of adverse outcomes. This includes patients at higher risk of unintended awareness and patients at higher risk of excessively deep anaesthesia. The E-Entropy and Narcotrend-Compact M monitors are also recommended as options in patients receiving total intravenous anaesthesia. • 1.4 Anaesthetistsusing EEG-based depth of anaesthesia monitorsshould have appropriate trainingand experience with these monitorsand understand the potential limitationsof their use in clinical practice.

  18. BIS • Bispectral index analysis • Monitors electrical activity and quantifies level of sedation • Aims: to reduce awareness; reduce over-/underdosing of drugs • Works best with hypnotic agents • Doesn’t work with ketamine; and less sensitive to sedative effect of opioids

  19. BIS • Displayed as a continuous trend • Facial electromyogram (EMG) • BIS • Signal Quality Index (SQI) • Forehead sensor • 4 tines

  20. Other Monitors • Narcotrend Compact-M • 3 electrodes are attached to the patient’s forehead to measure EEG. • E-Entropy • Combined analysis of EEG and EMG to estimate level of anaesthesia

  21. www.nationalauditprojects.org.uk 1st June 2012 – 31st May 2013

  22. What is NAP5? A year long national service evaluation of patient reports of Accidental Awareness during General Anaesthesia (AAGA) in the UK and Ireland

  23. Numerous studies report explicit AAGA in 1 : 600 general anaesthetics. With up to 50% of cases developing significant psychological sequelae. Few departments of anaesthesia recognise these numbers The face validity of this is questioned - where are all these cases?

  24. Many studies are old and precede newer drugs, reduction in use of NMBA, use of TIVA, depth of anaesthesia monitors, etc. There are no large cohorts of ‘aware patients’ from which learning has taken place (most big studies 10-20 patients) National approaches to prevention and management of AAGA is poorly mapped. The psychological and medicolegal impact of AAGA is poorly mapped.

  25. We aim…… To identify all reports of AAGA over one year and to learn as much as possible from those reports, both quantitatively and qualitatively. To look for themes and to learn from both reports of AAGA and actual AAGA events

  26. An AAGA eventis an instance of recall of events during general anaesthesia (ie after induction, during surgery or before full emergence) whether with or without pain or distress. This includes any complaint/statement ranging from a patient mentioning they have been aware to a member of a medical team (but not being perturbed by it) to a formal written complaint to the Trust/Board made by a patient extremely unhappy with their experiences.

  27. More information: NAP5 website www.nationalauditprojects.org.uk

  28. Phase 1NAP5 surveyIndividual permanent staff’s experiences of AAGA and strategies to prevent or managedue return by30th April 2012

  29. NAP5 Baseline Survey Results • Ascertain no. cases which were known in 2011 • All NHS hospitals participated; 82% of anaesthetists (consultants & SAS) • Reported incidence was 1 : 15 414 • 153 cases • 72 cases (47%) occurred at/after induction • 46 cases (30%) occurred during surgery • 35 cases (23%) occurred after surgery (before full recovery) • Low use of routine depth of anaesthesia monitoring (<2%) despite being widely available (62%)

  30. Why so low? • Under-reporting • No proper follow-up strategies • Poor channels for patients to report complaints • ‘Lesser cases’ are not reported by patients because they are seen as ‘trivial’ • Trainees did not complete the questionnaire • Over-reporting • False memories/dreaming • Cases reported arising from sedation • Incidence Decreasing • Increased use of supraglottic airways in place of ETT and NMBAs

  31. Summary • Awareness is a very rare but extremely serious failure of anaesthesia • NAP5 will hopefully provide interesting results and improve our knowledge into this area • Depth of anaesthesia monitors are to assist the clinician in their judgement of anaesthesia with other clinical signs, not in isolation

  32. Reference • McCombe K, Wijayasiri L, Patel A. The Primary FRCA Structured Oral Examination Study Guide 2, 2010. Radcliffe, Oxford. • NAP5: http://www.nationalauditprojects.org.uk/NAP5_Publications • NICE: http://guidance.nice.org.uk/DG6 • Yentis S, Hirsch N, Smith G. Anaesthesia and Intensive Care A-Z, 4th Edition, 2009. Churchill Livingstone, Edinburgh • Hardman JG, Aitkenhead AR. Awareness During Anaesthesia. CEACCP 2005; 5(6): 183-186 • Pandit JJ, Cook TM, Jonker WR, O’Sullivan E. A National Survey of Anaesthetists (NAP5 Baseline) to Estimate and Annual Incidence of Accidental Awareness during General Anaesthesia in the UK. Anaesthesia 2013; 68(4): 343-353

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