Difficult Intubation Score - Medical Algorithm

A scoring system based on physical attributes can be used to identify patients at risk for difficult tracheal intubation.

Definitions:

(1) thyromental distance (TMD): thyroid prominence to the chin

(2) vertical neck length: thyroid prominence to sternal notch

(3) neck circumference: circumference at the level of the cricoid

(4) anterior subluxation: ability to protrude the lower incisors beyond the upper incisors

Parameter	Score
receding chin or TMD < 7 cm	3
Mallampati's sign (uvula not visible)	2
restricted neck extension	2
protruding teeth	2
mouth opening < 4 cm	2
vertical neck length < 7.5 cm	1
neck circumference > 33 cm	1

score =

= SUM(scores for parameters present)

Compensatory Factors	Score
anterior subluxation possible	-1
mouth opening > 5 cm	-1
vertical neck length > 8 cm	-1
thyromental distance > 8 cm	-1
edentulous	-1

adjusted score =

= (score above) + SUM(compensatory factor scores)

Interpretation:

• maximum score: 13

• minimum score: 0

• minimum adjusted score: -5

• It is considered better to prepare for a difficult intubation unnecessarily (false positives) than not to be prepared for one (false negative).

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A Comprehensive Scoring System for Predicting Difficult Intubation