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

5. 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. Case 1

6. Flexible Fiberoptic Laryngoscopy Case 1

7. Rigid Fiberoptic Laryngoscopy Case 1

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 1.Difficulty in establishing and/or maintaining the patency of the upper airway. 2.Difficulty in performing direct laryngoscopy. 3.Difficulty with the placement and/or positioning of the endotracheal tube. 4.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 Clinical Setting Anesthesiologist’s Skills

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 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 This occurs when it 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)

15. There is no infallible method Variable number of false positive and false negative results However, an airway exam should always be conducted. 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)

16. Lehane and Cormack Classification

17. Direct Laryngoscopy

18. Evaluation of the Airway: Physical Examination.

19. The Mallampati Test

21. Features Suggesting the Presence of a Difficult Airway 1.Relatively long upper incisors 2.Prominent “overbite” (maxillary incisors anterior to mandibular incisors) 3.Inability to bring mandibular incisors in front of maxillary incisors 4.Interincisor distance less than 3 cm 5.Mallampati class greater than 2 6.Highly arched or narrow palate 7.Stiff or indurated mandibular space 8.Thyromental distance less than three finger breadths 9.Short neck 10.Thick neck 11.Limited range of motion of head and neck

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

23. Example: Arthrogryposis Multiplex Short thyromental distance Long upper incisors Cleft palate TMJ dysfunction

24. 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

25. 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 Practice Guidelines

26. Difficult Airway Algorithm

27. 1.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

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

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

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

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

32. Difficult Airway Algorithm B. Intubation Attempts After Induction of General Anesthesia Initial Intubation Attempts Successful Initial Intubation Attempts UNSUCCESSFUL From this point onwards consider 1.Calling for Help 2.Returning to Spontaneous Ventilation 3.Awakening the Patient

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

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

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

36. 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 Emergency Invasive Airway Access (tracheostomy or cricothyrotomy) SUCCESSFUL VENTILATION Invasive Airway Access Other Options Awaken Patient

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