Difficult airway algorithm

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.[1]

LOOK

  • Look at the patient externally for characteristics that are known to cause difficult laryngoscopy, intubation or ventilation[2]
  • 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

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"

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 [3]
  • Blind orotracheal intubation

Blind Naso Trach Intubation

  • Not as successful but still an option
  • Higher complication rate - bleeding, emesis, and airway trauma

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[4][5]
  • 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[6]
    • 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

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)

Surgical Airway

  • 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

Video

[[Category:WikEM]]

References

  1. Reed, M. et al. Can an airway assessment score predict difficulty at intubation in the emergency department? Emerg Med J. 2005 Feb; 22(2): 99–102. doi: 10.1136/emj.2003.008771
  2. Rennie LM, Dunn MJG, et al. Is the ‘LEMON’ method an easily applied emergency airway assessment tool? European Journal of Emergency Medicine 2004;11:154–7
  3. Driver, B. E., Prekker, M. E., Klein, L. R., Reardon, R. F., Miner, J. R., Fagerstrom, E. T., … Cole, J. B. (2018). Effect of Use of a Bougie vs Endotracheal Tube and Stylet on First-Attempt Intubation Success Among Patients With Difficult Airways Undergoing Emergency Intubation: A Randomized Clinical Trial. JAMA: The Journal of the American Medical Association, 319(21), 2179–2189.
  4. Zhu X-Y, Lin B-C, Zhang Q-S, Ye H-M, Yu R-J. A prospective evaluation of the efficacy of the laryngeal mask airway during neonatal resuscitation. Resuscitation. 2011;82(11):1405–1409. doi:10.1016/j.resuscitation.2011.06.010
  5. Calkins MD, Robinson TD. Combat trauma airway management: endotracheal intubation versus laryngeal mask airway versus combitube use by Navy SEAL and Reconnaissance combat corpsmen. J Trauma. 1999;46(5):927–932
  6. Beck, E., Kharasch, M., Casey, J., Ochoa, P., Menon, S., Calabrese, N. and Wang, E. (2011) ‘Percutaneous Transtracheal jet ventilation’, Academic Emergency Medicine, 18(5), pp. e38–e38.