**6.2 Ultrasound measured tongue thickness and difficult intubation**

Tongue thickness, measured by US, (**Figure 1**) greater than 6.1 cm, has been shown to be an independent predictor of difficult intubation with 75% sensitivity and 72% specificity. A ratio of tongue thickness to thyromental distance greater than 0.87 has an 84% sensitivity and 79% specificity for predicting difficult tracheal intubation [12].
