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Anesthesiology Information


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Anesthesiology Information

  1. 1. Awareness During Anesthesia Do You Remember…?
  2. 2. References <ul><li>Awareness during anesthesia </li></ul><ul><ul><li>Anesthesiology Clinics of North America Volume 20 • Number 3 • September 2002 </li></ul></ul><ul><li>Awareness with recall during general anesthesia – Incidence and risk factors </li></ul><ul><ul><li>Anesth Analg 86: 1084-1089, 1998 </li></ul></ul><ul><li>Awareness during anesthesia </li></ul><ul><ul><li>Anethesiology 2000; 92: 597-602 </li></ul></ul><ul><li>BIS Monitoring to Prevent Awareness during General Anesthesia </li></ul><ul><ul><li>Anethesiology 2001; 94:520-2 </li></ul></ul><ul><li>Awareness detected by auditory evoked potential monitoring </li></ul><ul><ul><li>BJA 91 (2): 209-2 (2003) </li></ul></ul>
  3. 3. Before talking about it… <ul><li>Did you ever forget anything…? </li></ul><ul><ul><li>Patients are concerned that they would not be asleep during their surgery ( more then 50%) </li></ul></ul><ul><ul><li>For anesthesiologists, awareness under anesthesia ranks second only to death as a “dreaded” complication </li></ul></ul>
  4. 4. Definitions <ul><li>Consciousness </li></ul><ul><ul><li>‘The state of being conscious; awareness of one’s own existence, sensation, thoughts, surroundings, etc’ </li></ul></ul><ul><li>Awareness </li></ul><ul><ul><li>‘Having knowledge, conscious, cognizant’ </li></ul></ul>
  5. 5. Incidence of awareness during anesthesia <ul><li>General surgery </li></ul><ul><ul><li>1960: 1.2% </li></ul></ul><ul><ul><li>2000: 0.11% to 0.16% </li></ul></ul><ul><li>Cardiac surgery </li></ul><ul><ul><li>1977: 5.8% </li></ul></ul><ul><ul><li>1998: 0.3% </li></ul></ul><ul><li>Other types of surgery </li></ul><ul><ul><li>Major trauma </li></ul></ul><ul><ul><ul><li>High from 11% up to 43% </li></ul></ul></ul><ul><ul><li>Obstetric surgery (C/S) </li></ul></ul><ul><ul><ul><li>1968: 11.8% </li></ul></ul></ul><ul><ul><ul><li>1991: 0.9% </li></ul></ul></ul>
  6. 6. Patient perceptions of awareness <ul><li>Most common      </li></ul><ul><ul><li>Sounds and conversation – 89% to 100%    </li></ul></ul><ul><ul><li>Sensation of paralysis - 85%    </li></ul></ul><ul><ul><li>Anxiety and panic     </li></ul></ul><ul><ul><li>Helplessness and powerlessness     </li></ul></ul><ul><ul><li>Pain - 39%   </li></ul></ul><ul><li>Least common      </li></ul><ul><ul><li>Visual perceptions     </li></ul></ul><ul><ul><li>Intubation or tube     </li></ul></ul><ul><ul><li>Feeling the operation without pain </li></ul></ul>
  7. 7. After-effects of Awareness During General Anesthesia <ul><li>Mental after-effects </li></ul><ul><ul><li>Muscle relaxation </li></ul></ul><ul><ul><li>Pain </li></ul></ul><ul><ul><li>Fear of dying </li></ul></ul><ul><li>Medico-legal after-effects </li></ul>
  8. 8. Mental after-effects <ul><li>37% of patients were responded with… </li></ul><ul><ul><li>Disbelief </li></ul></ul><ul><ul><li>Ignorance </li></ul></ul><ul><ul><li>Anger </li></ul></ul><ul><li>14% of patients were told… </li></ul><ul><ul><li>“ just a bad dream” </li></ul></ul><ul><ul><li>“ all in your imagination” </li></ul></ul><ul><ul><li>“ were med or hallucinating” </li></ul></ul><ul><ul><li>“ had a seventh sense” </li></ul></ul>
  9. 9. Then…there were <ul><li>Sleep disturbances  </li></ul><ul><ul><li>fear when falling asleep   </li></ul></ul><ul><li>Repetitive nightmares  </li></ul><ul><ul><li>52.4%   </li></ul></ul><ul><li>Anxiety and panic attacks  </li></ul><ul><ul><li>55%   </li></ul></ul><ul><li>Depression </li></ul><ul><li>Flashbacks    </li></ul><ul><li>Avoidance of medical care    </li></ul><ul><li>Preoccupation of death </li></ul><ul><li>Post-traumatic stress disorder (PTSD) </li></ul><ul><ul><li>14.3% to 22% </li></ul></ul><ul><ul><li>From months (20m) to years (17y)! </li></ul></ul>
  10. 10. Medico-legal after-effects <ul><li>Very large compensations… </li></ul><ul><ul><li>USD 1,000 to 600,000 </li></ul></ul><ul><li>Risk factors </li></ul><ul><ul><li>No volatile agents used </li></ul></ul><ul><ul><li>Female </li></ul></ul><ul><ul><li>Obstetric or gynecology procedure </li></ul></ul><ul><ul><li>Opioid only </li></ul></ul><ul><ul><li>Muscle relaxant </li></ul></ul>
  11. 11. Causes of Awareness <ul><li>  Light anesthesia      </li></ul><ul><ul><li>Nitrous/opioid/relaxant anesthesia     </li></ul></ul><ul><ul><li>Myocardial depression </li></ul></ul><ul><ul><li>Hypovolemia     </li></ul></ul><ul><ul><li>Cesarean section     </li></ul></ul><ul><ul><li>Difficult intubation     </li></ul></ul><ul><ul><li>Premature discontinuation of anesthetic    </li></ul></ul>
  12. 12. Causes of Awareness <ul><li>Machine malfunction or misuse of technique      </li></ul><ul><ul><li>Failure to check equipment     </li></ul></ul><ul><ul><li>Vaporizer and circuit leaks     </li></ul></ul><ul><ul><li>Intravenous infusion errors     </li></ul></ul><ul><ul><li>Accidental administration of muscle relaxant to awake patient    </li></ul></ul>
  13. 13. Causes of Awareness <ul><li>Increased anesthetic requirements      </li></ul><ul><ul><li>Variability in anesthetic requirements for intravenous agents     </li></ul></ul><ul><ul><li>Increased anesthetic requirement because of chronic alcohol, opioid, and cocaine abuse </li></ul></ul>
  14. 14. Causes of Awareness
  15. 15. Prevention of awareness <ul><li>Administer amnestic premedicants.    </li></ul><ul><li>Maintain vigilance regarding equipment and monitoring.    </li></ul><ul><li>Minimize use of complete neuromuscular blockade.    </li></ul><ul><li>Supplement nitrous/opiate anesthesia with a potent volatile anesthetic.    </li></ul><ul><li>Maintain 0.8–1.0 MAC of a potent volatile anesthetic by itself.    </li></ul><ul><li>Administer adequate dose of induction agent.    </li></ul><ul><li>Obtain informed consent for high-risk patients.    </li></ul><ul><li>Mask auditory input.    </li></ul><ul><li>Provide education.    </li></ul><ul><li>Monitor for awareness. </li></ul>
  16. 16. Methods of detecting awareness <ul><li>Postoperative interview </li></ul><ul><ul><li>Structured </li></ul></ul><ul><ul><li>Best </li></ul></ul><ul><li>Questions asked during interviews </li></ul><ul><li>What is the last thing you remember before going to sleep for the operation? </li></ul><ul><li>What is the first thing you remember after waking after the operation? </li></ul><ul><li>Do you remember anything in between? </li></ul><ul><li>Did you have any dreams? </li></ul><ul><li>What is the most unpleasant thing you remember from your operation and anesthesia? </li></ul>
  17. 17. Methods of Monitoring Consciousness During General Anesthesia <ul><li>Clinical signs </li></ul><ul><ul><li>Sympathetic activities: HR, BP, sweating, pupillary dilatation, lacrimation … </li></ul></ul><ul><ul><li>Unreliable </li></ul></ul><ul><li>Isolated forearm technique </li></ul><ul><li>EEG </li></ul><ul><ul><li>BIS </li></ul></ul><ul><ul><li>AEP </li></ul></ul>
  18. 18. Awareness detected by auditory evoked potential monitoring BJA 91 (2): 209-2 (2003) <ul><li>Case report </li></ul><ul><li>Accidental interruption of drug delivery is a common cause of awareness during general anesthesia </li></ul><ul><li>A rapid change of AEP was noted when infusion of anesthetics was stopped </li></ul>
  19. 19. Prevention and Management of Awareness
  20. 20. Conclusions <ul><li>Incidence in general anesthesia: 0.1-0.2% </li></ul><ul><li>Incidence in cardiac surgery: 0.3% </li></ul><ul><li>Lower dose of anesthetics are associated with higher incidence of intra-op awareness; insufficient concentration </li></ul><ul><li>Standard physiologic monitoring is not reliable, such as AEP or BIS; however, clinical signs are much more unreliable </li></ul><ul><li>Psychiatric after-effect of awareness range from no effect to PTSD </li></ul>
  21. 21. Conclusions <ul><li>There is no evidence that any kind of premedication would affect the incidence of awareness </li></ul><ul><li>If prolonged laryngoscopy is required, one should not forget to add the induction agents or inhalation agent </li></ul><ul><li>In critical hemodynamic situation, BZD instead of general anesthetics may be acceptable </li></ul><ul><li>NMBs should be used as sparingly as possible </li></ul><ul><li>If the patient has a history of awareness under anesthesia, it would be wise to use monitor </li></ul><ul><li>If the patient has suffered from awareness, psychiatric consultation and follow-up is recommended. </li></ul>
  22. 22. Discussion <ul><li>Structured post-operative interviews </li></ul><ul><ul><li>Best method </li></ul></ul><ul><ul><li>however </li></ul></ul><ul><ul><ul><li>Large number of patients </li></ul></ul></ul><ul><ul><ul><li>Very sick patients: difficult to interview </li></ul></ul></ul><ul><li>Feedback information to the anesthesiologists </li></ul><ul><ul><li>Education </li></ul></ul><ul><ul><ul><li>Incidence from 4% to 1.5% in one study </li></ul></ul></ul><ul><ul><li>Changes in drugs dosage </li></ul></ul><ul><ul><ul><li>Increase in volatile agents, I.V. anesthetic agents </li></ul></ul></ul><ul><ul><ul><li>Decrease in muscle relaxant </li></ul></ul></ul><ul><li>BZD? </li></ul><ul><ul><li>Have effect on memory but are not likely to be anesthetic </li></ul></ul>
  23. 23. Thanks for your attention!