Airway Management

1. Airway Management Sarah McPherson Gord McNeil July 17, 2003

2. What are the indications to intubate? • Failure to protect airway • Failure to oxygenate or ventilate • Anticipated course

3. Basic Airway Approach Needs intubation yes Crash Airway Unresponsive? Near death? no yes Predict difficult airway? Difficult Ariway no RSI

4. Basic Airway Approach Attempt Oral Intubation yes Post-intubation Management Successful? no BMV maintains SpO2 > 90%? no Failed Airway yes >3 Attempts at OTI by attending MD? yes

5. Airway Anatomy Epiglottis Aryepiglottic folds Arytenoid cartilage False vocal cords True vocal cords

6. Anatomy • Pediatric Airway Differences • Larger tongue • Large occiput • Anterior larynx • Larger epiglottis/floppier • Subglottic area narrowest • Less musculature • Shorter trachea • Narrower airway

7. 8 Steps to a Successful RSI • RSI 8 p’s: • Preparation • Peruse • Preoxygenate • Pretreatment • Paralysis • Protection • Placement • Post intubation management

8. Basic Airway Management - 8 P’s“Prepare” – SIGMA D What do you need for intubation? • SIGMA D • S = Suction • I = Intravenous • G= Gas • M = Mask/Bag • A =airway equipment (oral airway, laryngoscope, tubes, alternative) • D= Drugs

9. “Peruse” - LEMON LAW • L = Look: face, neck, chest • E = Examine: mouth, thyromental, floor of mouth to thyroid • M = Mallampatti: huge tongue?, back of throat? • O = Obstruction: tumor, epiglottitis • N = Neck mobility: OA, RA, syndromic

10. LEMON - Look • Look • Evaluate the pt. • Obesity • Micrognathia • High arched palate • Narrow face • Short or thick neck • Neck trauma • Large tongue • Presence of facial hair • Dentures • Large teeth

11. LEMON –Evaluate 3-3-2 • Evaluate 3-3-2 • Evaluate the anatomy • 3 fingerbreadths of mouth opening • 3 fingerbreadths between front of chin and hyoid • 2 fingerbreadths from mandible to thyroid cartilage • CAN I DISPLACE TISSUE SUB-MENTALLY?

12. Mallampati score Grade 1: entire post. Pharynx, visualized to tonsillar pillars No difficulty Grade 2: hard palate, soft palate and top of uvula only No difficulty Grade 3: hard and soft palate only Moderate difficulty Grade 4: no visualization post pharynx or uvula (hard palate only Severe difficulty LEMON – Mallampati score

13. LEMON -Obstruction • Obstruction • Look for upper and lower airway obstruction • foreign body aspiration • Epiglottitis • croup • Abscesses • others: surgery,tumors, radiation

14. LEMON –Neck Mobility • Neck Mobility • Collar, RA, degenerative arthritis, history of surgery • Note: get significant movement with BVM ventilation also!!

15. “Pre-oxygenate” - no bagging • Preoxygenate (nitrogen washout) • Saturate O2 reservoir, tissues and blood • 100% NRB (70%) • 5 min healthy adult • 2.5 min children • 8 VC breaths

16. How much time do I have? • 70kg adult maintains O2 sat >90% for 8 min • From 90% - 0% = < 120 seconds • Obese adult (>120kg) desaturate to 0% in less than 3 min • 10kg child desaturate <90 in 4 min • From 90% to 0% in 45 seconds

17. Walls graph

18. “Pre- medicate” - LOAD • Lidocaine: tight heads, tight lungs • Opioid: for blunting sympathetic response (ICP, IOP, aortic dissection, aneurysm, IHD) • Atropine: children <= 10 • Defasiculate: for increased ICP

19. Lidocaine ? • Premise • Laryngoscopy and Intubation • afferent stim. in post pharynx/ larynx • increased central stim • increased ICP • stim of autonomic system • increased HR / BP • upper and lower resp. tract leading to increased airway resistance

20. Lidocaine ? • Literature (supports) • suppresses cough reflex • attenuates increase in airway resistance (from ET tube irritation) • prevents increased ICP (normal increase with ETT is 22mmHg) • prevents increased IOP • decreases dysrhythmias by 30-40%

21. Lidocaine ? • Literature (?doesn’t support) • use to attenuate sympathetic response to laryngoscopy • Use: tight lungs / tight brains • 1.5mg/kg 3 min prior • Topical 4% lidocaine and ICP ????

22. Drugs to Decrease Sympathetic Response to Intubation (LOAD) • Fentanyl • high dose 5-10 ug/kg (will unequivocally block sympathetic response - hypotension, apnea , chest wall rigidity) • 1.5-3ug/kg (2 min prior) blocks increase BP but no effect on HR • Beta-blockers • will decrease sympathetic response • prob: neg ionotrope, bronchoconstriction

23. Drugs to Decrease Sympathetic Response to Intubation • Helfman et al • compared 200 lido, 200 fentanyl, 150 esmolol • esmolol only reliably agent in preventing rise in HR and BP • Chung et al • combination esmolol and fentanyl (2ug/kg and 2mg/kg) best combo with limited side-effects

24. LOAD - Atropine • Use with SUX in children under the age of 8 and when giving repeat doses to adults • Sinus brady, junctional, sinus arrest usually after a second dose • Reason: Sch mimicks action of Ach at the cardic muscarinic receptors • Dose 0.02mg/kg (no less than 0.1mg), 3 min prior to induction

25. LOAD - Atropine • Literature • Prevents brady in children • Reduces BUT doesn’t eliminate them in infants • No effect on older children • Anesthesia literature: volatile anesthetics in combination with atropine - increased risk of arrhythmias • Bottomline: Use atropine on children in the ED

26. Defasiculation • Decrease the rise in ICP from Sch induced fasciculation (animal data, limited human) • Does not attenuate the sympathetic response to intubation • Does not attenuate the increase in airway resistance with intubation • 1/10 intubating dose

27. RSI in Adults With Elevated Intracranial Pressure: A Survey of EmergencyMedicine Residency Programs • Am J Emerg Med :1995 • 100 programs surveyed • 67 responses, 65 used RSI in their programs!!! • Top NMB agents – Sux and vecuronium • Top induction agents - midazolam and thiopental • Lidocaine - was routine • Fentanyl - other pretreatment agent • Defasciculating dose used by most programs

28. Paralysis with induction • Rapid sequence - “intubation before aspiration” • Do not titrate • Midazolam, ketamine, thiopental or etomidate • Succinylcholine or rocuronium

29. Induction • Used to produce anesthesia and unconsciousness • Many options • Best choice depends on clinical and pharmacokinetic factors

30. Etomidate • Ultrashort acting non-barbiturate hypnotic agent (no analgesic effects) • Adv: • rapid onset and rapid recovery • hemodynamic stability • minimal resp depression • cerebral protection • Induction Dose: 0.3 mg/kg (decrease to 0.15 mg/kg if hemodynamic instability)

31. Etomidate • Onset : one arm-brain circulation (within 1 min) • Duration : 3-5 min • Cerebral • decreases CBF by 35% - decr ICP • no change MAP • CPP increases (increased cerebral oxygen/demand ratio) - decr ICP

32. Etomidate • Resp • minimal effects • doesn’t release histamine • CV • no change in HR/ MAP/ CI/ PAWP • Endocrine • concern re: steroid depression

33. Etomidate • Dose dependant reversible inhibition of 11-beta- hydroxylase (converts 11-deoxycortisol to cortisol) • Studies: • transient drop in cortisol levels with induction of anesthesia (6hrs), back to normal in 20 hrs • no reported adverse outcomes

34. Etomidate • Contraindications: age < 10, known seizure disorder, pregnant • Adverse effects • nausea and vomiting (30-40%) • pain on injection (similar to propofol) • myoclonic movement, may cause trismus • Pregnancy category C • embryocidal in rats

35. Ketamine • Phencyclidine derivative (similar to Angel Dust) • Dissociative anesthetic (dissociation between the thalmus and limbic system) • Sympathomimetic (increased HR and BP) • Increases cerebral blood flow by 60% potentially elevating ICP! • Reduces airway resistance • Dose 1-2mg/kg IV, 4-5mg/kg IM • Onset: within 60s

36. Thiopental • Barbituate, potentiates GABA • Cerebroprotective • Dose related potent venodilator and myocardial and resp depressant • Adult 1-4 mg/kg, child 1- 6 mg/kg • Onset 15 - 30 secs, duration 3- 5 min • Do not use in hypotension

37. Benzos and Narcotics • Benzos: • Midazolam • Dose: 0.5-2 mg/kg depending on hemodynamics and age of patient • often will cause hypotension • Narcotics • Fentanyl • Dose: 1-3 ug/kg • less hemodynamic effects than midaz but in high doses will cause hypotension • not great anestethic when used alone

38. Succinylcholine • Depolarizing NM agent • Onset: 30-45s • Duration: 5-10 min • Dosage (IV): • 1-1.5mg/kg adult • 2mg/kg child • 3mg/kg neonate • Can give IM at twice the dose

39. Succinylcholine • Side-effects? • Incr IOP, ICP • Bradycardia • Trismus-masseter muscle spasm • Fasciculations • Malignant Hyperthermia • Hyperkalemia (mean increase < 0.4mmol/L) • Prolonged blockade

40. Succinylcholine Contraindications • History of MH • Burns > 24 hrs old until healed • Muscle damage (crush) > 7 days - completely healed • Spinal cord injury, stroke (denervation UMN, LMN) > 7 days - 6 months • Neuromuscular disease, myopathies: indefinately as long as disease is active • Intra-abdominal sepsis > 7 days - resolution of infection • hyperkalemia

41. Sux - Hyperkalemia • Literature • Case reports since 1960’s • No case reports of hyperkalemia in the ED (multiple trauma, burns, neurological disease) • Literature poor with chronic renal failure • Zink et al • 100 pts (no risk factors) • Max increase 1.0 meq/L (K increased in 46pts, dropped in 46 pts and unchanged in 8) • 1 pt found to be in a wheelchair!, K dropped from 4.6 to 4.1

42. Sux - Hyperkalemia • Conclusion • Non high risk pts • No problems with administration • High risk pts • CRF probably okay • Others : literature is not great but we have good NDNM blockers, therefore no point to take risk

43. Sux – Raised IOP • Thought to be a contraindication to an open globe injury! • Pressure elevations do occur, are transient, maximal for 2-4 min post administration • Pressure elevations of 3-8mmHg (never been shown to worsen globe injury • Comparison: normal blink – increases IOP by 10-15mmHg, forceful closure of the eyelid >70 mmHg • Anesthesia continues to use Sux in OR with globe injuries • Chiu et al: • if you want to prevent increase in IOP, can give defasciculating dose of a NDNM blocker (rocuronium 2 min pre RSI)

44. Sux – Prolonged blockade • Pseudocholinesterase Deficiency • Congenital • Heterozygous : up to 25 min, homozygous up to 5 hrs after a single dose • Homozygous : 1 in 3000 pts • Acquired • Organophosphate poisoning • Cocaine use • CRF, severe liver disease, hypothyroidism,malnutrition, pregnancy, cytotoxic drugs, metoclopramide, bambuturol(long acting beta 2 anonist) • Note: above none have prolonged blockade over 20-25 min

45. Sux – Trismus/Masseter muscle Spasm • Occasionally can get spasm • Especially in children • Transient • If prolonged, severe and other muscle involved should think of MH

46. Malignant Hyperthermia • Genetic skeletal muscle membrane abnormality - never been an ED case reported • Onset acute or delayed - 60% mortality • Clinically • Muscle rigidity • Autonomic instability • Hypoxia • Hypotension • Hyperkalemia • Lactic acidosis • Temp. elevation is a late sign • treat with dantrolene (2mg/kg iv q 5min to max 10mg/kg)

47. Rocuronium • Aminosteroid, non-depolarizing neuromuscular blocker • Agent of choice when sux is CI • Onset: 1.2-1.8 min (sux 0.8-1.2) • Dose: 0.6 mg/kg • Duration of action: 30 -45min

48. Rocuronium • Cannot depend on neostigmine in failed intubation - time to recovery will be too long • Histamine related hypotension • Primary use of non-depolarizing agents is for defasiculation and paralytic maintenance post-intubation

49. Paralytics (table)

50. Timing • 10 minutes out: • Prepare (SIGMA D) Peruse (LEMON) • 5 minutes out: Pre-oxygenate • 3 minutes out: Pre-treat (LOAD) • Zero: Paralysis with induction • Zero +30 sec: Pressure and position • Zero +45 sec: Pass tube - jaw flaccidity • Zero +1 minute: Post-tube mngmt