Outline how you would assess a patient for potential difficulty with endotracheal intubation.
History: of previous difficulty with intubation, infections/swelling affecting mouth or neck, problems with mouth opening or neck movement (arthritis, cervical spine injury), problems with teeth (especially caps/crowns, jaw wiring etc.). Review of a previous anaesthetic chart.
Examination (multiple components) consider:
• Teeth (maxillary anterior to mandibular; length of upper incisors; ability to prognath mandible; inter-incisor distance [need > 3 cm])
• Pharynx (ability of visualise uvula and tonsillar pillars; height and narrowness of palate).
• Mandibular space (thyromental distance 2: 3 fingerbreadths [6 cm]; compliance and distensibility of submandibular space).
• Length of neck (qualitative: short neck more difficult eg. syndromes).
• Thickness of neck (qualitative: thick neck decreases ability to align planes).
• Range of motion (of head and neck: eg. sniffing position)
• Consider also the ability to assess potential difficulties by actually having a look with a laryngoscope. (10 marks)
In some situations specific investigations may also be indicated (eg. neck X-rays etc.)
There are numerous anatomical and historical features which predict difficult intubation.
Specific pathologies associated with difficult intubation:
Physical examination: general features
Mouth, face and jaw examination
Neck and posture
LEMON is a nice short way of remembering what to look for. It certainly seems to be reliable in predicting difficult intubation:
Evaluate: 3:3:2 rule
Obesity and obstruction
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