The difficult airway

LEMON Mnemonic

• An airway assessment score based on criteria of the LEMON method is able to successfully stratify the risk of intubation difficulty in the emergency department.

LOOK

• Look at the patient externally for characteristics that are known to cause difficult laryngoscopy, intubation or ventilation

• Trauma
• Short neck
• Micrognathia
• Prior surgery
• May also be difficult to bag
  • Body mass index
  • Advanced age
  • Beard
  • No teeth
  • Snoring
  • Dentures

Evaluate 3-3-2-1

• 3 - Ideally the distance between the patient's incisor teeth should be at least 3 finger breadths
• 3 - Distance between the hyoid bone and the chin should be at least 3 finger breadths
• 2 - Distance between the thyroid notch and the floor of the mouth should be at least 2 finger breadths
• 1 - Lower jaw should not sublux more than 1cm

Mallampati

• The patient sits upright, opens mouth and protrudes tongue
• Grades are based on visibility of the uvula, posterior pharynx, hard, and soft palate

Obstruction

• Assess for conditions leading to airway obstruction such as Peritonsillar Abscess (PTA), trauma, or Epiglottitis.

Neck Mobility

• Patient places chin down onto their chest and extend their neck.
• Remove the hard collar and provide manual stabilization in trauma patients.
• Poor neck mobility impacts ability to have airway access alignment.

Mallampati Score

3-3-2 ruleDistance between patient's incisor teeth of 3 finger breadths and distance between the thyroid notch and the floor of the mouth should be at least 2 finger widths

ASA Difficult Airway Algorithm

• Does not necessary apply to the ED since the patient can always be awakened and case cancelled
  • Cricothyrotomy should always be the last step in patients with failure to oxygen and ventilate with BVM and inability to intubate
  • Straight blade- Miller- may offer better manipulation of a large epiglottis in children or for micrognathia or "buck teeth"

Improving Passive Oxygenation

• Use in overweight, poor O2 reserve, hypoxia at baseline, concerns for rapid progression to hypoxia once apnea
• Pre-oxygenate while sitting upright, only lay back once RSI drugs pushed.
• 30 degrees reverse trendelenburg position for intubation
• Nasal O2 while pre oxygenating and DURING intubation (after induction increase to 15L)

Airway Adjuncts

Endotracheal tube introducer (ETI)/Gum Elastic Bougie

• Higher first pass success when used with direct laryngscope vs. styletted ET tube regardless of whether difficult airway was expected or not
• Blind orotracheal intubation

Blind Naso Trach Intubation

• Not as successful but still an option
• Higher complication rate - bleeding, emesis, and airway trauma
  • Do not attempt in patients with posterior pharyngeal swelling such as in Angioedema (Upper Airway)

Lighted Optical Stylets

• High success rate - especially good for trauma, c-spine precautions
• Use for both reg and nasotrach
• Lower complication rate
• Limited by fogging, secretion, recognition of anatomy, cost, and rare provider experience

LMA

• Can use without muscle relaxants
• Better than face mask
• Can be used as bridge to fiberoptic intubation
• Limited by unreliable seal at peak insp pressure
• Aspiration risk
• Mucosal trauma
• LMA better than endotracheal for paramedics, especially in pediatric patients

• Intubating LMA (LMA-Fastrach) provides the opportunity to convert to a definitive airway after rescue with the supraglottic device

Combitube- esoph obturator

• Good for nurses and paramedics with limited intubation skill
• Indicated if difficult airway predicted: cannot see glottis with laryngoscope
• Reduced risk for aspiration compared to face mask or LMA
• Can maintain spinal immobilization
• Large size predisposes to esophogeal dilatation and laceration as a complication

Percutaneous transtracheal ventilation

• PTV
• Prefered over crithyrotomy in children up to age 10-12
• Needle, 16-18ga through cricoid membrane, connected to 50 psi 02
  • Oxygenates well
  • Ventilate through glottis and upper airway - can retain CO2
• Need adequate oxygen pressure
• 1 sec insp and 2- 3 sec exp to avoid breath stacking
• Can use for 30-45 min
• May cause pneumothorax or barotrauma
• Contraindications
  • Distorted anatomy
  • Bleeding diathesis
  • Complete airway obstruction

Retrograde Intubation

• Percutaneous guide wire through cricoid and retrograde intubation over wire
• Use guide catheter over wire and then ett
• Need time to set up
• Risk hematoma, pneumothorax
• Contraindicated
  • Bleeding
  • Distorted anatomy

Fiberoptic Bronchoscopic Intubation

• Takes time to set up
• Good for c-spine injury or awake patient with diff airway
• Go through nose
• Use for all ages, can give 02 during procedure thru fiberscope, immediate confirmation of position
• Limited by secretions, bleeding, poor suction,

Rigid Fiberoptic Laryngoscopes

• Use for diff airway or spinal immobolization
• Not as good and longer time to intubate than flex scope

Surgical cricothyrotomy

• Can get subglottic stenosis
• Rapid 4 step procedure faster but higher complication rate - cric cart fx
• Can also do wire guided
• Long term morbid, mortality similar to tracheostomy

See Also

Airway Pages

• Pre-intubation
  • Predicting the difficult airway
  • Bag valve mask ventilation
    • Oropharyngeal airway
    • Supraglottic airway
  • Apneic oxygenation
    • EBQ:ED Preoxygenation
• Induction
  • Critical care quick reference
  • Rapid sequence intubation
  • Delayed sequence intubation
• Intubation
  • Intubation (peds)
  • Direct laryngoscopy
  • Video Laryngoscopy
  • Bougie
  • The difficult airway
  • Advanced airway adjuncts
    • Supraglottic airway
  • Non-traditional intubation
    • Awake intubation
    • Nasal intubation
    • Blind digital intubation
• Surgical airways
  • Surgical cricothyrotomy
  • Needle cricothyrotomy
  • Pediatric jet ventilation
• Post-intubation
  • Mechanical ventilation (main)
  • Deterioration after intubation (DOPE)

Video

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