Assessing the Difficult Airway in the ED University of Utah Affiliated Emergency Medicine Residency Program July, 2009 Erik D. Barton, MD, MS, MBA

Outline The Failed Airway Defining the Difficult Airway Difficult Airway prediction tools Evidence-based experience

The “Failed” Airway Multiple Definitions… Number of failed attempts (e.g., three) Failure to ventilate with a BVM Failure to oxygenate Failure to visualize the larynx

The Failed Airway Clinically, 2 types of “failed” airways: 1. Cannot intubate, but can oxygenate 2. Cannot intubate, and cannot oxygenate

The Failed Airway Type 1: (Can’t intubate, can oxygenate) Most common airway problem! Failure to intubate on 3 attempts by an experienced operator National Emergency Airway Course Consider alternative techniques / adjuncts

The Failed Airway Type 2: (Can’t intubate, can’t oxygenate) Oxygen saturation <90% with BVM Any number of attempts Surgical airway Cricothyrotomy Percutaneous technique

Rapid Sequence Intubation Failed Attempt Rescue Maneuvers The first rescue from failed intubation is bagging. The first rescue from failed bagging is better bagging. Rescue devices

Rapid Sequence Intubation Failed Attempt Rescue Maneuvers Plan in advance Systematic approach essential Equipment Training …remember “Skydiving!!”

The Difficult Airway The DIFFICULT AIRWAY is something you PREDICT… A FAILED ARWAY is something you EXPERIENCE!!

Predictors of Difficult Intubation The Difficult Airway Predictors of Difficult Intubation Rely on luck,….very high stakes Adopt the Anesthesia checklist? A simpler, more reliable system is needed.

Identification of the Difficult Airway 3 Key Attributes Difficult Bag/Mask Ventilation Difficult Intubation Difficult Cricothyrotomy

Difficult Bag/Mask Ventilation The Difficult Airway Difficult Bag/Mask Ventilation

Difficult Bag/Mask Ventilation The Difficult Airway Difficult Bag/Mask Ventilation Defined as: leak, H2O seal, change operator, sat < 92%, O2>15L, no chest movement 1502 patients, 75 (5%) had difficult BMV 5 attributes by MV analysis: beard, bmi>26kg/m2, snoring, edentulousness, age>55 > 2 attributes = 72% sens, 73% spec Langeron O, et al: Prediction of Difficult Mask Ventilation. Anesthesiology 2000; 92:1229-1236.

Difficult Bag/Mask Ventilation The Difficult Airway Difficult Bag/Mask Ventilation Anesthesiologist’s gestalt 17% sensitive but 96% specific Only 1/1502 (0.06%) impossible BMV 0.7% impossible intubation, 44% of those had difficult BMV = 0.3% overall Langeron O, et al: Prediction of Difficult Mask Ventilation. Anesthesiology 2000; 92:1229-1236.

Mask seal Obesity Aged (>55) No teeth Stiff lungs Approach to the Difficult Airway Difficult Bag Mask Ventilation Mask seal Obesity Aged (>55) No teeth Stiff lungs

Difficult Crycothyrotomy The Difficult Airway Difficult Crycothyrotomy

Difficult Cricothyrotomy The Difficult Airway Difficult Cricothyrotomy little literature guidance more of a “gestalt” local neck anatomy probably the only real issue

Surgery scar Hematoma Obesity Radiation Tumor Difficult Cricothyrotomy Approach to the Difficult Airway Difficult Cricothyrotomy Surgery scar Hematoma Obesity Radiation Tumor

The Difficult Airway Difficult Intubation

Predictors of Difficult Intubation The Difficult Airway Predictors of Difficult Intubation Most based on laryngoscope grade Numerous external attributes implicated Some systems very complex, some simple Various definitions of difficult intubation Mallampati scale widely used, but crude Difficult to apply complex scales in crisis Few have been prospectively validated

Predictors of Difficult Intubation The Difficult Airway Predictors of Difficult Intubation Dentition Upper airway attributes Mouth/oral access Anatomic abnormalities Immobilized trauma patient Facial/neck trauma Underlying conditions Short neck Small occiput Facial hair Airway obstruction Large tongue High larynx Small mandible

BMV as important as intubation Mouth opening/access The Difficult Airway Identification of the Difficult Airway BMV as important as intubation Mouth opening/access Neck extension at AOJ Neck flexion at CTJ Mentum-Hyoid-Thyroid distance Presence/Risk of obstruction

The LEMON law Identification of the Difficult Airway Approach to the Difficult Airway Identification of the Difficult Airway Development of a consistent approach: The LEMON law © National Emergency Airway Management Course

The LEMON law L ook externally E valuate 3-3-2 M allampati Approach to the Difficult Airway The LEMON law L ook externally E valuate 3-3-2 M allampati O bstruction? N eck mobility © National Emergency Airway Management Course

L ook externally Identification of the Difficult Airway Approach to the Difficult Airway Identification of the Difficult Airway L ook externally Difficult BMV (MOANS) Difficult Cricothyrotomy (SHORT) Intubator Gestalt

Or some other thyromental distance equivalent Approach to the Difficult Airway Identification of the Difficult Airway E valuate 3-3-2 Or some other thyromental distance equivalent

M allampati Identification of the Difficult Airway Approach to the

Mallampati

O bstruction? Identification of the Difficult Airway Approach to the

N eck mobility Identification of the Difficult Airway Approach to the

The LEMON law L ook externally MOANS, SHORT E valuate 3-3-2 Approach to the Difficult Airway The LEMON law L ook externally MOANS, SHORT E valuate 3-3-2 M allampati O bstruction? N eck mobility © National Emergency Airway Management Course

The Difficult Airway Prediction Tools Do they really work? 850 intubations over 37 months 838 patients underwent RSI 3 failed intubations 452 (53%) could not follow simple commands 370 (44%) were C-spine immobilized RESULTS = only 32% of ED patients could be assessed by LEMON criteria Levitan, et al, Ann Emer Med, 2004

The Difficult Airway Prediction Tools Air Medical Prehospital intubations Swanson & Barton, ACEP, 2004

The Difficult Airway Prediction Tools Air Medical Prehospital intubations Swanson & Barton, ACEP, 2004

The LEMON Score ED study in the UK Prospective, Observational study June 2002 to September 2003 156 patients undergoing intubation Compared LEMON scores to Cormack-Lehane visualization grades Grade 1 view = “easy” Grade 2, 3, 4 view = “difficult” Reed, Dunn et al, Emerg Med J, 2005

Cormack-Lehane Laryngoscopic Visualization Grades Grade I Grade II Grade III Grade IV

The LEMON Score Reed, Dunn et al, Emerg Med J, 2005

The LEMON Score Reed, Dunn et al, Emerg Med J, 2005

The LEMON Score Reed, Dunn et al, Emerg Med J, 2005

The “LEON” Score Reed, Dunn et al, Emerg Med J, 2005

Need a consistent approach Awake techniques by default The Difficult Airway Management of the Difficult Airway Need a consistent approach Awake techniques by default Need definition of and preplanned approach to failed airway No “one trick pony” approach Alternative devices

The Difficult Airway… Alternative devices? Superglottic: LMA, Combitube, King tube Fiberoptic devices: flexible, rigid, hand-held Lighted stylets: Trachlight, Lightwand Surgical: open, transtracheal

Is Nasal Intubation an Option?

Putting it all together… Are there any contraindications for RSI? Is intubation predicted to be successful? Is bag-valve-mask predicted to be successful? Cricothyrotomy difficulties? Can you consider “awake” laryngoscopy (or nasal)? Is this a “failed” airway? What type of failed airway?

The Emergency Difficult Airway Algorithm The Difficult Airway The Emergency Difficult Airway Algorithm Emergency airway management is different Key driver is that patient MUST be intubated NOW ASA Difficult Airway Algorithm breaks down Emergency Algorithm addresses necessity Prediction tools have limitations: LEMON criteria cannot be universally applied Consistent use will predict most of the difficult patients

The End! QUESTIONS??