The Difficult Airway Rafael Ortega, M.D. Associate Professor of Anesthesiology Boston University School of Medic

1. The Difficult Airway Rafael Ortega, M.D. Associate Professor of Anesthesiology Boston University School of Medicine Recognition, Management, and Prevention of Operating Room Catastrophes American College of Surgeons 89th Clinical Congress October 20th, 2003

2. OBJECTIVES To define the “Difficult Airway”. To predict who has a Difficult Airway. To review the management and alternatives.

3. Importance • Adverse outcomes associated with the difficult airway include: • Death • Brain injury • Myocardial injury • Airway trauma

4. Importance 30% to 40% of all anesthetic deaths are attributed to the inability to manage a difficult airway. Caplan RA. Posner KL. Ward RJ. Cheney FW. Adverserespiratoryevents in anesthesia: a closed claims analysis. Anesthesiology. 72(5):828-33, 1990

5. Case 1 A woman with a frontal lobe brain tumor was scheduled for a craniotomy. She was otherwise healthy but had a hoarse voice. She attributed her hoarseness to cigarette smoking.

6. Case 1 Flexible Fiberoptic Laryngoscopy

7. Case 1 Rigid Fiberoptic Laryngoscopy

8. Case 1: Reinke’s Edema (Smoker's laryngitis, Polypoid degeneration, Polypoid corditis) Vocal fold enlargement caused by gelatinous submucosal edema arising from the area beneath the surface of the vocal folds (Reinke's Space).

9. Difficult Airway: Definition The clinical situation in which there is difficulty with mask ventilation, difficulty with tracheal intubation, or both. American Society of Anesthesiologists Task Force on Management of the Difficult Airway: Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology 2003; 98: 1269–77

10. Definition Expanded • Difficulty in establishing and/or maintaining the patency of the • upper airway. • Difficulty in performing direct laryngoscopy. • Difficulty with the placement and/or positioning of the • endotracheal tube. • Difficulty associated with the potential for contamination of the • unprotected airway by foreign material and/or difficulty brought • about by contamination.

11. Interplay of Factors Patient Specific Factors Anesthesiologist’s Skills Clinical Setting

12. Incidence Reported incidence: failed mask ventilation: 0.01-0.03% failed intubation: 0.03-0.05%. Samsoon GL, Young JR: Difficult tracheal intubation: a retrospective study. Anaesthesia 1987; 42: 487-90 Williams KN, Carli F, Cormack RS: Unexpected, difficult laryngoscopy: a prospective survey in routine general surgery. British Journal of Anaesthesia 1991; 66: 38-44 Rocke DA, Murray WB, Rout CC, Gouws E: Relative risk analysis of factors associated with difficult intubation in obstetric anesthesia. Anesthesiology 1992; 77: 67-73

13. Difficult Mask Ventilation Difficulty with mask ventilation is a situation during which an anesthesiologist cannot provide adequate face mask ventilation due to inadequate mask seal, excessive gas leak, or excessive resistance to the ingress or egress of gas. (usually involves oxygen desaturation <90%) American Society of Anesthesiologists Task Force on Management of the Difficult Airway: Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology 2003; 98: 1269–77

14. Difficult Laryngoscopy and Endotracheal Intubation This occurs whenit is not possible to visualize any portion of the vocal cords after multiple attempts with conventional laryngoscopy and/or when tracheal intubation requires multiple attempts in the presence or absence of tracheal pathology. (usually more than three attempts and/or more than 10 minutes) American Society of Anesthesiologists Task Force on Management of the Difficult Airway: Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology 2003; 98: 1269–77

15. Identifying Patients with Difficult Airways • Problematic • There is no infallible method • Variable number of false positive and false negative results • However, some features in the airway exam can suggest difficulty.

16. Identifying Patients with Difficult Airways “falsely predicting a difficult airway has few adverse consequences, but being unprepared when it occurs may lead to serious complications” (Kristensen M: Predicting difficult intubation. Anaesthesia 2002; 57: 612) • Always conduct an exam • Be prepared

17. Lehane and Cormack Classification

18. Direct Laryngoscopy

19. Evaluation of the Airway: Physical Examination.

20. The Mallampati Test

21. The Mallampati Test

22. Features Suggesting the Presence of a Difficult Airway • Relatively long upper incisors • Prominent “overbite” (maxillary incisors anterior to mandibular incisors) • Inability to bring mandibular incisors in front of maxillary incisors • Interincisor distance less than 3 cm • Mallampati class greater than 2 • Highly arched or narrow palate • Stiff or indurated mandibular space • Thyromental distance less than three finger breadths • Short neck • Thick neck • Limited range of motion of head and neck

23. Limited range of motion of head and neck Rheumatoid Arthritis

24. Example: Arthrogryposis Multiplex • Short thyromental distance • Long upper incisors • Cleft palate • TMJ dysfunction • Stiff neck

25. Practice Guidelines American Society of Anesthesiologists Task Force on Management of the Difficult Airway: Practice guidelines for management of the difficult airway: an updated report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology 2003; 98: 1269–77

26. Practice Guidelines • Consultants exhibited the strongest agreement • on the potential beneficial effects of: • conduct of the airway history and physical examination • advance preparation of the patient and equipment • formulation of strategies for intubation and extubation

27. Difficult Airway Algorithm

28. Difficult Airway Algorithm It is assumed that the clinician understands how the risk of gastric content aspiration influences management choices.

29. Difficult Airway Algorithm • Assess the likelihood and clinical impact • of basic management problems: • A. Difficult Ventilation • B. Difficult Intubation • C. Difficulty with Patient Cooperation or Consent • D. Difficult Tracheostomy

30. Difficult Airway Algorithm 2. Actively pursue opportunities to deliver supplemental oxygen throughout the process of difficult airway management.

31. Difficult Airway Algorithm 3. Consider the relative merits and feasibility of basic management choices: Intubation Attempts After Induction of General Anesthesia Awake Intubation A. Vs. Invasive Technique for Initial Approach to Intubation Non-Invasive Technique for Initial Approach to Intubation B. Vs. Preservation of Spontaneous Ventilation Ablation of Spontaneous Ventilation C. Vs.

32. Difficult Airway Algorithm 4.Develop primary and alternative strategies: B. Intubation attempts after Induction of general anesthesia • Awake Intubation

33. Difficult Airway Algorithm A. Awake Intubation Airway Approached by Non-invasive Intubation Invasive Airway Access Succeed FAIL Invasive Airway Access Cancel Case Consider Other Options (LMA, Local, Nerve Block)* *Usually assumes mask ventilation will not be problematic.

34. Difficult Airway Algorithm B. Intubation Attempts After Induction of General Anesthesia Initial Intubation Attempts UNSUCCESSFUL Initial Intubation Attempts Successful From this point onwards consider • Calling for Help • Returning to Spontaneous Ventilation • Awakening the Patient

35. Difficult Airway Algorithm …but what if spontaneous ventilation does not return or awakening the patient is not possible?

36. Difficult Airway Algorithm Initial Intubation Attempts UNSUCCESSFUL Face Mask Ventilation Adequate Face Mask Ventilation Not Adequate NON-EMERGENCY PATHWAY (Ventilation adequate but intubation unsuccessful) Success Failure EMERGENCY PATHWAY!

37. Difficult Airway Algorithm NON-EMERGENCY PATHWAY (Ventilation adequate but intubation successful) Alternative Approaches to Intubation (different laryngoscopes, LMA as intubating conduit, fiberoptic intubation, retrograde intubation, stylets, light-wand, blind intubation, other) Successful Intubation Fail After Multiple Attempts Invasive Airway Access Consider Other Options (LMA, Local, Regional) Awaken Patient

38. Difficult Airway Algorithm EMERGENCY PATHWAY! (Inadequate Ventilation and Unsuccessful Intubation) Call for Help Emergency Non-Invasive Ventilation (rigid bronchoscope, esophageal-tracheal combitube,transtracheal jet ventilation, other) FAIL SUCCESSFUL VENTILATION Emergency Invasive Airway Access (tracheostomy or cricothyrotomy) Awaken Patient Other Options Invasive Airway Access

39. Summary • Definition “Difficult Airway”. • Predictors of the Difficult Airway. • ASA algorithm for Difficult Airway Management