Assessing the Difficult Airwayin the ED

University of Utah AffiliatedEmergency 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

• The first rescue from failed intubation is bagging.

• The first rescue from failed bagging is better bagging.

• Rescue devices

Failed Attempt

Rescue Maneuvers

Rapid Sequence Intubation

Failed Attempt

• Plan in advance• Systematic approach essential• Equipment• Training

…remember “Skydiving!!”

Rescue Maneuvers

The Difficult Airway

The DIFFICULT AIRWAY is something you PREDICT…

A FAILED ARWAY is something you EXPERIENCE!!

The Difficult Airway

Predictors of Difficult Intubation

Rely on luck,….very high stakes

Adopt the Anesthesia checklist?

A simpler, more reliable system is needed.

The Difficult Airway

Identification of the Difficult Airway3 Key Attributes

• Difficult Bag/Mask Ventilation• Difficult Intubation• Difficult Cricothyrotomy

The Difficult Airway

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.

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.

Approach to the Difficult Airway

Difficult Bag Mask Ventilation

Mask sealObesityAged (>55)No teethStiff lungs

The Difficult Airway

Difficult Crycothyrotomy

The Difficult Airway

Difficult Cricothyrotomy

• little literature guidance• more of a “gestalt”• local neck anatomy probably the

only real issue

Approach to the Difficult Airway

Difficult Cricothyrotomy

Surgery scarHematomaObesity RadiationTumor

The Difficult Airway

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

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

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

Approach to the Difficult Airway

Identification of the Difficult Airway

Development of a consistent approach:

The LEMON law

© National Emergency Airway Management Course

Approach to the Difficult Airway

L ook externallyE valuate 3-3-2M allampatiO bstruction?N eck mobility

The LEMON law

© National Emergency Airway Management Course

Approach to the Difficult Airway

Identification of the Difficult Airway

L ook externally- Difficult BMV (MOANS) - Difficult Cricothyrotomy (SHORT)- Intubator Gestalt

Approach to the Difficult Airway

Identification of the Difficult Airway

E valuate 3-3-2

Or some other thyromental distance equivalent

Approach to the Difficult Airway

Identification of the Difficult Airway

M allampati

Mallampati

Approach to the Difficult Airway

Identification of the Difficult Airway

O bstruction?

Approach to the Difficult Airway

Identification of the Difficult Airway

N eck mobility

Approach to the Difficult Airway

L ook externallyMOANS, SHORT

E valuate 3-3-2M allampatiO bstruction?N eck mobility

The LEMON law

© National Emergency Airway Management Course

The Difficult AirwayPrediction 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 AirwayPrediction Tools

331Total Patients

280GCS Motor < 6

51GCS Motor = 6

26Trauma patient

25 (8%)No Trauma &

GCS Motor = 6

209Trauma

71No Trauma

Swanson & Barton, ACEP, 2004

Air Medical Prehospital intubations

22Failed Intubations

20GCS Motor < 6

2GCS Motor = 6

2Trauma patient

0No Trauma &

GCS Motor = 6

19Trauma

1No Trauma

The Difficult AirwayPrediction Tools

Swanson & Barton, ACEP, 2004

Air Medical Prehospital intubations

• 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

The LEMON Score

Cormack-Lehane Laryngoscopic Visualization Grades

Grade I Grade II

Grade III Grade IV

The LEMON ScoreReed, Dunn et al, Emerg Med J, 2005

The LEMON ScoreReed, Dunn et al, Emerg Med J, 2005

The LEMON ScoreReed, Dunn et al, Emerg Med J, 2005

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

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 Difficult AirwayThe 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??