Anesthetic Emergence

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Anesthetic Emergence

  1. 1. ANESTHETIC EMERGENCE<br />Alan Julius Sim, MD, Fellow<br />Divison of Liver Transplantation <br />Mount Sinai HELPS Center<br />Department of Anesthesiology<br />Mount Sinai School of Medicine<br />New York, NY<br />
  2. 2. Famous Quotes<br />“Never say their name more than twice, otherwise you’ll look like you don’t know what you’re doing”<br />Ian Sampson, MD<br />“Dude, just cause you put the tube in dosen’t mean you gotta take it out”<br />KhinMarlar, MD<br />“Every textbook tells you how to put someone to sleep, no book will ever tell you how to wake someone up”<br />Samuel DeMaria Jr., MD<br />“As long as their breathing on their own, not in pain, and have a pulse, I don’t care what you gave”<br />Corey Scher, MD<br />
  3. 3. Objectives<br />Plan and implement an appropriate emergence technique <br />Assess depth of neuromuscular blockade<br />Reverse neuromuscular blockade<br />Remove or discontinue maintenance anesthetics (inhaled or intravenous)<br />Verify reversal of neuromuscular blockade<br />Ensure adequate post-operative analgesia<br />Extubate patient safely<br />Potential problems <br />
  4. 4. Emergence Philosophy<br />Most anesthesiologists, surgeons, and nurses will place a premium on a “smooth” emergence, free of coughing, straining, or arterial hypertension<br />It should be acknowledged that there is a paucity of clinical data to give any perspective to the actual magnitude of risks associated with an emergence that is not “smooth”<br />
  5. 5. Planning Emergence<br />When do you start to prepare for emergence?<br />
  6. 6. Planning Emergence<br />When do you start to prepare for emergence?<br />Prior to Induction of Anesthesia<br />Shorter acting agents for shorter cases<br />Avoid excessive premedications<br />Prepare to switch techniques or agents at the end of a longer case<br />Time your medications and doses<br />
  7. 7. Assess Depth of NMB<br />How can you assess depth of neuromuscular blockade?<br />
  8. 8. Assess Depth of NMB<br />How can you assess depth of neuromuscular blockade?<br />Objectively<br />Train of Four – Adductor Pollicis or OrbicularisOculi<br />95% – 1 twitch<br />90-95% - 2 twitches<br />80-85% - 3 twitches<br />75-80% - 4 twitches<br />>100% ???? - 0 twitches<br />Subjectively<br />Timing and amount of last dose<br />Spontaneous respiratory effort<br />
  9. 9. Assess Depth of NMB<br />When can I reverse?<br />
  10. 10. Assess Depth of NMB<br />When can I reverse?<br />Objectively<br />Post-tetanic stimulation and return of 1 twitch = 10 mins<br />At least 1 twitch represents 95% blockade and no free drug<br />Therefore, reliably reversible<br />Subjectively<br />Spontaneous respiratory effort<br />Less than 100% blockade<br />Therefore, reliably reversible<br />
  11. 11. Reverse NMB<br />How do I reverse NMB?<br />What agents do we use?<br />How do they work?<br />
  12. 12. Reverse NMB<br />How do I reverse NMB?<br />Anticholinesterase Inhibitors<br />Edrophonium 1-1.5mg/kg<br />Neostigmine 0.04-0.08mg/kg<br />Pyridostigmine 0.1-0.25mg/kg<br />These agents increase Ach EVERYWHERE, ideally want to isolate only nicotinic receptors and avoid muscarinic action and cholinergic crisis<br />Therefore, must administer concurrently anticholinergics<br />Atropine 0.4-1mg<br />Glycopyrolate 0.2-1mg<br />
  13. 13. Reverse NMB<br />How fast does reversal work?<br />
  14. 14. Reverse NMB<br />How fast does reversal work? <br />Dependent on five factors<br />Depth of block<br />Greater blockade = more to reverse<br />Type of anticholinesterase<br />Edrophonium > Neostigmine > Pyridostigmine<br />Dose of anticholinesterase<br />Maximum dose<br />Too much ACh can cause depolarizing blockade<br />Spontaneous reversal and metabolism of NMB agent<br />Intermediate vs. Long, patient factors<br />Concentration of anesthetic gas<br />Increased depth of inhaled augments blockade<br />
  15. 15. Reverse NMB<br />Any side effects of over-reversal? <br />
  16. 16. Reverse NMB<br />Any side effects of over-reversal? <br />Cholinergic Crisis<br />Wet<br />Bronchospasm<br />Paralysis<br />Bradycardia<br />Anti-Cholinergic Crisis<br />Dry<br />Hyperthermia<br />Urinary Retention<br />Tachycardia<br />Delayed emergence<br />
  17. 17. Reverse NMB<br />Atropine or Glycopyrrolate? <br />
  18. 18. Reverse NMB<br />Atropine or Glycopyrrolate?<br />Atropine<br />Better timing with edrophonium<br />Quicker onset of action<br />7 to 10 µg/kg of atropine should be given with 0.5 to 1.0 mg/kg of edrophonium<br />Crosses Blood-Brain barrier  Sedation/Hallucinations<br />Glycopyrrolate<br />Better timing with neostigmine<br />Less profound tachycardia<br />Better anti-sialigogue<br />7 to 15 µg/kg of glycopyrrolate should be given with 40 to 70 µg/kg of neostigmine<br />Quaternary structure <br />
  19. 19. Anesthesia “Off”<br />How do I go about doing this?<br />
  20. 20. Anesthesia “Off”<br />How do I go about doing this?<br />Inhaled<br />Dependent upon ventilation, FGF, and concentration gradient<br />Low Flow and Hypoventilation = Slow<br />High Flows and Hyperventilation = Fast<br />Blood:Gas Solubility and Lipid Solubility<br />Why does Desflurane take longer than N2O?<br />Intravenous<br />Dependent on beta half-life and length of infusion<br />No end-tidal propofol<br />Wake up will also depend on patient and level of stimulation!<br />Most importantly COMMUNICATE!!<br />
  21. 21. Verify NMB Reversal<br />How do I know I’m fully reversed?<br />Is spontaneous breathing OK with adequate tidal volumes?<br />
  22. 22. Verify NMB Reversal<br />How do I know I’m fully reversed?<br />Objective<br />TOF, seeing 4 twitches are subjective and indicate only 75% blockade<br />Sustained tetanus 50-100Hz >5s without fade indicates only 50% blockade<br />TOF ratio of >0.7-0.9 is the gold standard<br />Subjective<br />5 sec head lift<br />Tongue protrusion<br />Forced hand grip<br />Spontaneous breathing with adequate TV is still unreliable as diaphragm much more resistant to NMB than airway muscles (i.e. tongue)<br />
  23. 23. Post-Operative Analgesia <br />How can I prevent my patient from waking up in pain?<br />
  24. 24. Post-Operative Analgesia <br />How can I prevent my patient from waking up in pain?<br />Timing of narcotics (onset and duration)<br />Use longer acting narcotics early<br />Titrate shorter acting narcotics to respiratory rate<br />Use doses appropriate for “awake” patients<br />Use adjuncts<br />Acetaminophen<br />Gabapentin<br />Ketorolac<br />Regional<br />Block<br />Local infiltration<br />
  25. 25. Post-Operative Nausea <br />How can I prevent my patient from puking in my face?<br />
  26. 26. Post-Operative Nausea <br />How can I prevent my patient from puking in my face?<br />Avoid nauseating anesthetics<br />Opioids<br />Nitrous Oxide<br />Anticholinesterase Inhibitors<br />Use antiemetics appropriately<br />Dexamethasone 4mg pre-incision<br />Ondansetron 4mg pre-induction or 30 mins prior to emergence<br />Droperidol 0.625-1.25mg <br />Propofol 20-30mg close to emergence<br />
  27. 27. Extubation<br />When do I pull the tube? Deep or Awake?<br />
  28. 28. Extubation<br />When do I pull the tube? Deep or Awake?<br />Deep Extubation<br />Patient Selection<br />Recovery of NMB must be confirmed<br />> 1 MAC <br />RR < 15<br />Clear secretions<br />Always prepare for laryngospasm and reintubation<br />Need PACU cooperation<br />“Smooth”<br />Often Risk > Benefit<br />
  29. 29. Extubation<br />When do I pull the tube? Deep or Awake?<br />Awake Extubation<br />Mental Status<br />Follows commands<br />Airway<br />Can protect airway<br />Appropriate cough or gag “Bucking”<br />No edema<br />Difficult intubation?<br />Respiratory Mechanics<br />Strong<br />SpO2 > 93% on FiO2 < 0.5<br />Hemodynamics<br />Stable<br />Unlikely coming back to OR<br />
  30. 30. Style Points: Art or Science? <br />When is the patient ready to wake up? <br />
  31. 31. Style Points: Art or Science? <br />When is the patient ready to wake up?<br />Make sure surgery is done first<br />Look for hemodynamic changes<br />Increase HR<br />Increase BP<br />Return of reflexes<br />Swallowing<br />Lid reflex<br />Glabellar Tap<br />Can call first name if reflexes have returned<br />
  32. 32. Style Points: Art or Science? <br />How do I extubate awake but without bucking? <br />
  33. 33. Style Points: Art or Science? <br />How do I extubate awake but without bucking?<br />Bucking is a reflexive response to a noxious stimulus <br />Narcotics attenuate this response<br />LTA or lidocaine will “numb” the cords<br />Hyperventilation or hypocarbia will decrease drive to breathe against vent<br />Turn vent off upon recognition of patient wakefulness<br />Awake patients on narcotics can and will breathe<br />You just may have to tell them to <br />
  34. 34. Style Points: Art or Science? <br />There are three commonly practiced emergence “techniques” at Mount Sinai, each with unique advantages and disadvantages<br />Traditional<br />The 15/15<br />The Crash Wake-Up<br />
  35. 35. Style Points: Art or Science? <br />Traditional Wake-Up Method<br />Reverse NMB<br />“Lighten” anesthetic<br />Increase EtCO2<br />Return to spontaneous breathing<br />Titrate narcotics to RR<br />Extubate when patient is awake and following commands<br />Advantages<br />Smooth, adequate analgesia, comforting<br />Disadvantages<br />Requires breathing patient<br />Slow, hypoventilation decreases elimination of anesthetic<br />Increased side effects of narcotics <br />
  36. 36. Style Points: Art or Science? <br />The 15/15<br />Reverse NMB<br />Titrate down inhaled anesthetic<br />Dose narcotics appropriately<br />15L FGF 15 RR<br />Hyperventilate inhaled gas off<br />Extubate when patient is awake and following commands<br />Advantages<br />Fast emergence, smooth when timed correctly<br />Disadvantages<br />May not adequately ensure post-operative analgesia<br />Overdose or underdose narcotics to RR<br />
  37. 37. Style Points: Art or Science? <br />The Crash Wake Up<br />Full Reverse NMB<br />15L FGF 15 RR<br />Hyperventilate inhaled gas off<br />Push Naloxone<br />Pinch Nipples<br />Jaw-Thrust<br />Extubate when patient is awake and following commands<br />Advantages<br />Fast emergence when unprepared<br />Disadvantages<br />Never smooth<br />
  38. 38. Potential Problems<br />“Patient is too tight, need a little bit longer”<br />“The medical student is going to close”<br />
  39. 39. Potential Problems<br />“Patient is too tight, need a little bit longer”<br />Push something<br />ED95 of muscle relaxants is usually 1/3 intubating dose<br />Propofol<br />Lidocaine 1-1.5mg/kg<br />Push nothing<br />Increase inhaled concentration<br />N2O<br />Communicate<br />
  40. 40. Potential Problems<br />“He’s waking up all crazy”<br />
  41. 41. Potential Problems<br />“He’s waking up all crazy”<br />Emergence Delrium<br />Can happen if wake up is too fast or inadequate pain control<br />Rule out: Hypercarbia, Hypoxia, Hypotension<br />Stage II anesthesia<br />What to do<br />Don’t pull out ETT if haven’t already<br />Stop and hit rewind Propofol<br />Fentanyl<br />Droperidol<br />Avoid benzos if possible<br />
  42. 42. Potential Problems<br />“I pulled the tube and uhhh…he stopped breathing”<br />
  43. 43. Potential Problems<br />“I pulled the tube and uhhh…he stopped breathing”<br />Most anesthetic mishaps happen from extubation to PACU<br />Rule out laryngospasm vs. apnea<br />If apnea, attempt to ventilate off residual gas and stimulate<br />Consider naloxone, residual NMB<br />If laryngospasm, sustained PPV and prepare succynlcholine<br />Both cases prepare to re-intubate<br />Succynlcholine in successive doses?<br />Do not leave OR until you are assured patient is OK<br />Be prepared for long trips<br />
  44. 44. Potential Problems<br />“Why won’t he wake up?”<br />
  45. 45. Potential Problems<br />“Why won’t he wake up?”<br />Delayed emergence<br />Rule out: Hypercarbia, Hypoxia, Hypotension<br />Intoxication<br />Inadequate Reversal or Prolonged Paralysis<br />Phase II block?<br />Psudeocholinesterase deficiency<br />Metabolic<br />Hyper/Hyponatremia<br />Hyper/Hypoglycemia<br />Neurologic<br />Stroke<br />If residual paralysis, obligated to keep patient asleep<br />
  46. 46. Summary<br />Emergence is an art, there are many ways to do it<br />There is a lot of science to it also<br />Certain components must be performed<br />Reversal is not benign<br />But necessary if you paralyze<br />Communication is key<br />Involve yourself with the case at hand, and you will time everything perfectly<br />Never compromise patient safety <br />Anoxic brain injury infinitely much worse than “bucking”<br />
  47. 47. Thank You<br />“That was the best wake up I’ve ever seen, by the way, we’re number 12 for PACU”<br />

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