awareness in service
TRANSCRIPT
Awareness of AwarenessRoy Esaki
September 6 2012PACU
“Every year 20 million people are put under anesthesia. 1 in 500 stay awake the whole time” ◦ –Claim from Awake
Intraoperative Awareness
Public Awareness and Concern
Survey of 130 patients assessing importance of postoperative outcomes:
◦ 20% of people reported “recall without pain” as the most important concern
◦ Overall relative weights:
Vomiting 18 Gagging on ETT 17.9 Pain 17.0 Recall without pain 13.8 Nausea 11.8 Residual weakness 8.0
Macario, A&A; 1999
Patient Concerns
Clinical Background◦ Etiology◦ Clinical Features◦ Diagnosis
Brain Function Monitors
Treatment and Prevention
“Awareness” without general anesthesia
Overview
“Explicit recall of sensory perceptions during general anesthesia”
What is intraoperative awareness?
Vs “Awareness” during MAC or Dreams(Correlate patient report with surgical events)
Inadequate Anesthetic Effect◦ Inadequate dose (TIVA)◦ Resistance to anesthetic◦ Machine malfunction
May result in:◦ Immediate emotional and physiological response◦ Long-lasting Anxiety/PTSD◦ Avoidance of future medical care or surgeries◦ Lawsuits
Causes and Consequences
Mashour, A&A, 2010
Generally accepted incidence 0.1-0.3%
◦ Full range from .007-1%◦ 2004 JCAHO Sentinel alert: 20,000-40,000 cases of awareness
annually out of 21 million general anesthetics
Incidence
1. Sandin, 20012. Sebel, 2004
Risk Factors
High Risk Surgeries:
•Cardiac Surgery
•Trauma
•(Emergent) Cesarean Section
High Risk Situations:
•Difficult intubation
•Hypovolemia
•TIVA
•Paralysis
Clinical Signs◦ Sympathetic activation◦ Movement, Lacrimation, Sweating
Isolated Forearm◦ Inflate tourniquet prior to muscle relaxant (like ECT)
Brain Function Monitors◦ Processed EEG to “quantify” depth of sedation◦ BIS, SEDLine, Narcotrend
Intraoperative Diagnosis
Principle of Depth of Anesthesia Monitors
Measure frontal cortex activity (+/-) EMG signalAnalyze FrequencyProprietary and empirically derived formula outputs number indicating “depth of anesthesia”
Various Monitors
BIS (Bi-spectral index)
SEDLINE (Patient State Index)
Keep value 40-60 for general anesthesia
BIS value
◦ Unchanged by nitrous oxide◦ Ketamine increases BIS value◦ Lower BIS index in neurological impairment
Cerebral ischemia Dementia Hypoglycemia
Caveats
Highly controversial◦ Industry-sponsored trials◦ Direct-to-consumer advertising by device manufacturer
“B-aware” study (Myles, 2004)◦ 2643 patients at high risk of awareness◦ Routine (11/1418) ) vs BIS (2/1225) guided anesthesia◦ 82% Reduction of awareness by BIS; NNT =138
“B-unaware” study (Avidan, 2008)◦ 2000 high-risk patients◦ End-tidal anesthetic gas-based protocol (2/974) vs
BIS (2/967)◦ No reduction in awareness
Ongoing Multi-center studies for average-risk patients
Does BIS work?
2006 ASA Task Force on Intraoperative Awareness”
“Brain function monitoring is not routinely indicated for patients undergoing general anesthesia, either to reduce the frequency of intraoperative awareness or to monitor depth of anesthesia”◦ “There is insufficient evidence to justify a standard, guideline, or
absolute requirement that (depth of anesthesia) devices be used to reduce the occurrence of intraoperative awareness in high-risk patients undergoing general anesthesia
BIS Not Routinely Indicated
2007 Cochrane Review:
◦ Modest reduction in intraoperative primary anesthetic agent
◦ Faster recovery Eye opening 2.4 minutes
Verbal Command 2.3 minutesExtubation 3 minutes
Decreased PACU stay by 6.8 minutes) No change in time to home readiness
◦ Less post-operative nausea/vomiting
Significantly reduced the incidence of intraoperative recall awareness in surgical patients with high risk of awareness (OR 0.20, 95% CI 0.05 to 0.79).
Benefits to BIS
Listen, reassure, acknowledge◦ Document details of patient report◦ Open-ended (vs leading) questions
Alert anesthesia team involved with case Offer medical and mental health follow-up Contact risk management (Anesthesia provider)
Novel Treatment◦ Psychotherapy + Gradual desensitization to OR
If a patient reports awareness
Mashour, Anesthesiology 2008
32 year old woman underwent a cesarean delivery. When interviewed about anesthetic problems postoperatively, she complained of “hearing conversations, seeing bright lights, and feeling as though she were underwater. She was quite distressed by the recollections, as she “felt as though she were dead”
A Case of Awareness:
Patients report “awareness”◦ Occasionally with psychiatric consequences◦ Patients report “awareness” to online awareness database,
future anesthesia providers
Similar incidence of complaints of awareness in general (.023%) vs MAC or regional anesthesia ( .03%)
“Awareness” During Sedation
Mashour, A&A, 2009
117 patients undergoing regional anesthesia or MAC◦ Structured pre-operative and post-operative
interviews
Examined role of expectations for level of consciousness
Source of Expectation
Esaki, A&A, 2009
Nurse
Expected vs Experienced level of Consciousness
1-10 scale (completely asleep to completely awake)
Patients less awake than expected (15%) Patients more awake
than expected (8%)
Patients heavily sedated, or amnestic during previous MAC think they received general anesthesia may expect complete loss of consciousness for all future (MAC) cases
Appropriate message for MAC case:
◦ “Don’t worry you’ll be asleep for the whole procedure”
vs
◦ “We’ll keep you comfortable and will give you medication for pain and anxiety” “You may fall asleep or forget what happened, but that doesn’t
mean it’s general anesthesia” It’s like having a lot to drink—some people remember bits and
pieces or don’t remember all
“Going to sleep”
“The distinction between general and nongeneral anesthesia is often unclear from the patient’s perspective.
Anesthesia providers might better educate patients regarding intraoperative levels of consciousness and postoperative recall.”
Punchline
The perioperative health care team
Esaki RK, Mashour Ga. Complaints Of Intraoperative Awareness After Regional Anesthesia And Sedation, In: Consciousness, Awareness, And Anesthesia, Mashour Ga Ed. Cambridge University Press. 2010
Esaki RK, Mashour GA. Level of Consciousness Monitoring, In: Hand book of Anesthesia Equipment, Sandberg W ed. Elsevier. 2011.
Mashour GA, et al. A retrospective study of intraoperative awareness with methodological implications. Anesth Analg 2009;108:521–6
Mashour, et al. A Novel Classification Instrument for Intraoperative Awareness Events. Anesth Anal 2010; 110: 813-815
Sebel PS, et al. The incidence of awareness during anesthesia: a multicenter United States study. Anesth Analg 2004;99:833–9
Sandin RH, et al. Awareness during anaesthesia: a prospective case study. Lancet 2000; 355:707–11
Pollard RJ, et al. Intraoperative awareness in a regional medical system: a review of 3 years’ data. Anesthesiology 2007;106:269–74
Selected References