Background: To determine the most accurate predictor in evaluating difficult
visualization of larynx (DVL) using indicators of modified mallampati test
(MMT), sternomental distance (SMD) and inter incisor gap (IIG), either in
isolation or in combination.
Methods: Two hundred eighty three patients were participated in the study and
evaluated for their possibility of having DVL. The difficulty of larynx visualization
was evaluated using direct laryngoscopy based on grading of the Cormack and
Lehane (CL) classification. The CL grades III and IV were considered as difficult
visualization of larynx. DVL was also predicted using the airway predictors of
MMT, SMD and IIG. The cut-off points for the airway predictors were
Mallampati III and IV; ≤ 12,5 cm, and ≤ 3 cm, respectively. Moreover, sensitivity,
specificity, positive and negative predictive value and area under the curve (AUC)
of each predictor were determined, either in isolation or in combination.
Independent predictors of DVL were determined using logistic regression
analysis.
Results: Difficulty to visualize the larynx was found in 29 (10.2%) subjects. The
sensitivity, specificity, positive predictive value and AUC for the airway
predictors were: MMT (20.8%; 99.7%; 71.4%; 68%), SMD (72.4%; 97.2%; 75%;
88%), and IIG (41.4%; 99.4%; 85.7%; 73%). The best combination of predictors
was SMD + IIG with an AUC of 90.2%. Triple combination of MMT + SMD +
IIG showed the same value of AUC with combination of two predictors, SMD +
IIG.
Conclusion: This study suggests the combination of IIG + SMD predictors as the
optimal diagnostic model to predict DVL in a Malay race population in
Indonesia.
Keywords: Difficult visualization of larynx (DVL), Mallampati score,
Sternomental Distance (SMD), Inter incisor gap (IIG).