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