TT	Tongue thickness
SHBD	Skin-to-hyoid-bone distance
CTML	Cricothyroid membrane length
DMV	Difficult mask ventilation
DL	Difficult laryngoscopy
DI	Difficult intubation
AUC	Area under the ROC curve
ROC	Receiver-operating characteristic
PPV/NPV	Positive/negative predictive value
LR	Likelihood ratio