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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??