Airway Emergencies - assessment - 2
Relative tongue/pharyngeal size
- Degree of visibility of oropharyngeal structures including extent of mandibular opening ie. Mallampati classification
- Best performed with patient sitting, head in extension, tongue out
- Correlates with laryngoscopic view:
Class 1= Grade 1 view 99-100% of the time
Class 4= Grade 3 or 4 view 100% of the time
Mallampati classification
- Class 1- soft palate, fauces, uvula, anterior and posterior pillars visible
- Class 2- soft palate, fauces uvula visible
- Class 3- soft palate, base of uvula visible
- Class 4- soft palate not visible
Mandibular Space
- Space anterior to the larynx determines how easily the laryngeal axis will fall in line with the
pharyngeal axis when the atlanto-occipital joint is extended.
- If the thyromental distance is very short, the laryngeal axis will make
a more acute angle with the pharyngeal axis and it will be more difficult for
atlanto-occipital extension to bring these 2 axes into line.
Thyromental distance
- Distance should be measured from inside of mentum to thryoid cartilage.
- A thyromental distance of > 6 cm and a horizontal length of mandible of > 9 cm
strongly suggest that direct laryngoscopy will be relatively easy
Atlanto-occipital joint extension
- When the neck is flexed on the chest (25-35°) and the atlanto-occipital joint is well extended head
extended on the neck, the pharyngeal and laryngeal axes are brought more closely into a straight line-sniff
position.
- When the atlanto-occipital joint cannot be extended, attempts to do so cause
the convexity of the cervical spine to bulge anteriorly, pushing the larynx
more anterior.
St. Vincent's Hospital Melbourne. Department of Anaesthesia. ©2003
