New Orleans EMS Airway Lecture
Series: Lecture 1
Predicting the Difficult Airway
Jeffrey M. Elder, M.D.
Deputy Medical Director
When To Intubate?
• Failure to maintain/protect the airway
– Required for successful oxygenation and ventilation
– Reflexes avoid aspiration
– Clear vocal communication is a good measure for
airway protection/patency
– Absence of a gag reflex not sensitive or specific as
indicator for the need of an airway (swallowing)
• Swallowing requires sensing the presence of pooled material
and complex muscular actions to swallow
– Spontaneous respirations ≠ airway protection
When To Intubate?
• Failure of Ventilation or Oxygenation
– Supplemental oxygen not effective: ARDS
– Respiratory fatigue/failure: Asthma
– Can be reversible: Opioid overdose
When To Intubate?
• Anticipated Clinical Course
– Deterioration of the critically ill
– Patient is exposed to a period of increased risk:
• Long transport time, air evacuation, etc.
– Requires clinical gestalt
• Examples:
– Head injury/combative
– Expanding hematoma
Approach to Evaluating the Airway
• Ask a question: What is your name?
– Response can tell you about airway and
neurological status
– Normal voice, ability to inhale and exhale in a
manner required for speech, comprehending the
question
– Only tells you about 1 moment in time
– If unable to phonate properly: perform a detailed
assessment of the airway
Approach to Evaluating the Airway
• Examine Mouth and Oropharynx
– Bleeding
– Swelling of Mouth or Uvula
– Any abnormality that would interfere with the
passage of air
• Examine Mandible and Central face integrity
Approach to Evaluating the Airway
• Examine the Anterior Neck, Larynx, and
Trachea:
– Palpate for subcutaneous air
• Tracheal injury, pulmonary injury, esophageal rupture,
gas forming infections
• Monitor the Respiratory Pattern
– Stridor = upper airway obstruction
Approach to Evaluating the Airway
• Observe the chest through several respiratory
cycles
– Look for symmetrical, concordant chest
movement
– Paradoxical movement or flail chest
– Diaphragmatic breathing – spinal cord injury
Approach to Evaluating the Airway
• Auscultation of the chest
– Assess adequacy of air exchange
– Decreased breath sounds in hemothorax,
pneumothorax, or other pulmonary process
• Monitor pulse oximetry, capnography, and
mentation
– ABGs rarely helpful in the decision to intubate
• Anticipate clinical course!
Identification of the Difficult and Failed
Airway
The Failed Airway
• Failure to maintain acceptable oxygen
saturation during or after on or more failed
laryngoscopic attempts (CICO)
or
• Three failed attempts at orotracheal
intubation by an experienced intubator, even
when oxygen saturation can be maintained.
Clinical presentations of the Failed
Airway
• There is not sufficient time to evaluate or
attempt a series of rescue options, and the
airway must be secured immediately because
of an inability to maintain O2 sats via BVM.
(CICO)
• There is time to evaluate and execute various
options because the patient is in a “can’t
intubate, can oxygenate situation”
Four Technical Operations of the
Difficult Airway
• Difficult Bag Valve Mask Ventilation
– MOANS
• Difficult Laryngoscopy and Intubation
– LEMON
• Difficult Extra-Glottic Device
– RODS
• Difficulty Cricothyrotomy
– SHORT
Difficult Bag-Mask Ventilation: MOANS
• Mask Seal
• Obstruction/Obesity
• Age >55
• No Teeth
• Stiff lungs
Difficult Laryngoscopy and Intubation:
LEMON
• Look Externally
• Evaluate 3-3-2
• Mallampati Score
• Obstruction/Obesity
• Neck Mobility
Difficult Laryngoscopy and Intubation:
LEMON
• Look Externally
• Gestalt
• Gut Feeling
• First Impression – “This looks bad!”
Difficult Laryngoscopy and Intubation:
LEMON
• Evaluate 3-3-2 Rule:
– Relates the mouth opening to size of the mandible
to the position of the larynx in terms of likelihood
of successful visualization of the glottis by direct
laryngoscopy
Difficult Laryngoscopy and Intubation:
LEMON
• Mouth must open adequately to permit
visualization past the tongue when both the
blade and ET tube are within the oral cavity
• The mandible must be sufficient size to allow the
tongue to be displaced fully into the
submandibular space
• The glottis must be located a sufficient distance
caudad from the base of the tongue so that a
direct line of site can be created to look from
mouth to vocal cords as the tongue is displaced
inferiorly
Difficult Laryngoscopy and Intubation:
LEMON
• First “3”
• Assesses for mouth
opening
• 3 fingers between the
upper and lower
incisors
Difficult Laryngoscopy and Intubation:
LEMON
• Second “3”
• Length of the
Mandibular space
• Mentum to hyoid
Difficult Laryngoscopy and Intubation:
LEMON
• “2”
• Position of the glottis in
relation to the base of
the tongue
• Space from Chin-neck
junction (hyoid) to and
thyroid notch
Difficult Laryngoscopy and Intubation:
LEMON
• Mallampati
– Sitting Up
– Head in sniffing position
– Open mouth, protrude tongue without phonation
• Class I-IV
• Class I & II = low intubation failure rate
• Class III & IV = intubation failure may be > 10%
Difficult Laryngoscopy and Intubation:
LEMON
Difficult Laryngoscopy and Intubation:
LEMON
• Obstruction/Obesity
• Four Cardinal Signs of Upper Airway
Obstruction:
– Muffled voice
– Difficulty swallowing secretions
– Stridor
– Sensation of dyspnea
Difficult Laryngoscopy and Intubation:
LEMON
• Stridor
– Occurs when airway circumference is less than
50% of normal (4.5mm or less)
• May quickly lead to total obstruction with
administration of opiates or benzos
– Loose the stenting of open airways
• Prepare for double set up
Difficult Laryngoscopy and Intubation:
LEMON
• Neck Mobility
– C spine immobilization
may compound the
effects of other difficult
airway markers
• Trauma, RA, Ankylosing
Spondylitis
• May require video
laryngoscopy
Difficult Extraglottic Device: RODS
• Restricted Mouth Opening
• Obstruction
• Disrupted or Distorted Airway
• Stiff Lungs or Cervical Spine
Difficult Extraglottic Device: RODS
• Restricted Mouth
Opening
– Allowing for oral access
to insert device
Difficult Extraglottic Device: RODS
• Obstruction
– Upper airway obstruction at larynx or below
Difficult Extraglottic Device: RODS
• Disrupted or Distorted
Airway
– Seat/Seal compromised
of the device
Difficult Extraglottic Device: RODS
• Stiff Lungs or Cervical Spine
– Increased airway resistance
• Severe Asthma
– Decreased pulmonary compliance
• Pulmonary Edema
– Decreased Cervical Movement
Difficult Cricothyrotomy: SHORT
• Surgery or Disrupted Airway
• Hematoma (infection/abscess)
• Obesity
• Radiation
• Tumor
Difficult Cricothyrotomy: SHORT
• Surgery or Airway
Disruption
– Anatomy distortion
– Halo Device
Difficult Cricothyrotomy: SHORT
• Hematoma
– Infection
– Trauma or Postop
– Not a contraindication
Difficult Cricothyrotomy: SHORT
• Obesity
–
–
–
–
Access
Short neck
Large pannus
Subcutaneous
Emphysema
– Careful palpation to
overcome!
Difficult Cricothyrotomy: SHORT
• Radiation
– Distortion of Anatomy
– Scar Tissue
– Fixed Flexion Deformity of the Spine
Difficult Cricothyrotomy: SHORT
• Tumor
– Extrinsic
– Intrinsic
Acknowledgement
• Manual of Emergency Airway Management,
3rd Edition. Walls, R. and Murphy, M. 2008.