Last Updated on July 3, 2022
–Recognizing difficult airway—
Content
(1) Difficult to Ventilate with a BVM — MOANS
(1) Difficult to Ventilate with a BVM — MOANS
• M: Male / Difficult mask seal / Mallampati 3 or 4
• O: Obstruction of upper airway
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Further reading:
1. Prehospital management of difficult airway, JEMS
(2) Difficult Laryngoscopy & Intubation — LEMON
Look externally
e.g. obesity, high-arched palate, short neck, facial / neck trauma
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Evaluate 3-3-2 rule
• MOUTH — 3 fingers should fit mouth opening (interincisor distance // Patil’s test)
• UNDER CHIN — 3 fingers should fit the space between mentum to hyoid bone
• THYROMENTAL DISTANCE — 2 fingers should fit the space between inner border of mentum to upper border of thyroid cartilage
→ Indicates floor of mouth is adequate in size to accommodate tongue
**Use patient’s own fingers
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Mallampati score & grade of laryngeal view
Mallampati classes I & II / Laryngeal grade I & II: good laryngeal visualisation, low intubation failure rates
Mallampati classes III & IV / Laryngeal grade III & IV: poor laryngeal visualisation, higher intubation failure rates
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Obstruction
e.g. presence of foreign body in airway, disruption of integrity of airway
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Neck mobility
• Neck should be able to be positioned in ‘sniffing position‘ i.e. flexion at cervical spine + extension at atlanto-occipital joint
• Causes of decreased neck mobility e.g. trauma, arthritis
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4D approach
Dentition
Distortion
presence of vomitus, secretions, blood, bone fragments obscuring airways
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Disproportion
receding chin with large tongue; buck teeth
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Dysmotility
Notes
Causes of upper airway obstruction
• Intraluminal —
Q&A
Reference
1. The LEMON approach for predicting the difficult airway – Resus
2. Guide to the essentials in Emergency Medicine (2nd ed)