Could mandibular profile angle or inter-pterygoid distance provide a novel method for predicting difficult laryngoscopy?

Background: Various tests have been developed to predict difficult airway during preoperative examination, but none has presented an adequate degree of accuracy. This study investigates novel mandibular structures and angles for evaluation as potential predictor of difficult laryngoscopy.

Methods: Following Ethics Committee approval, 1001 patients scheduled for elective surgeries under general anesthesia with oral intubation were included in this prospective study. Difficult laryngoscopy was defined as a Cormack-Lehane grade III or IV view. Standard predictive tests - including neck circumference, thyromental distance, sternomental distance, Modified Mallampati Test (MMT), mouth opening, and upper lip bite test - were evaluated alongside two novel parameters: the "mandibular profile angle" and "inter-pterygoid distance."

Results: The sensitivity and specificity of the Modified Mallampati Test (MMT) for predicting difficult laryngoscopy were 46% and 91%, respectively, with a positive predictive value (PPV) of 51% and a negative predictive value (NPV) of 89%. In contrast, the "mandibular profile angle" demonstrated a sensitivity of 83%, specificity of 86%, PPV of 55%, and NPV of 96%. The "inter-pterygoid distance" showed similar accuracy, with a sensitivity of 82%, specificity of 88%, PPV of 58%, and NPV of 96%. The area under the curve (AUC) values were 0.89 for the "mandibular profile angle" and 0.90 for the "inter-pterygoid distance." The optimal cut-off for predicting difficult laryngoscopy was 107.75° for the "mandibular profile angle" and 13.05 cm for the "inter-pterygoid distance."

Conclusions: These findings suggest that using mandibular structures in preoperative assessments to anticipate and prepare for difficult laryngoscopy scenarios provides reliable threshold values that may improve patient safety and procedural outcomes. The introduction of novel measurements, specific to mandibular structure assessment, carries the potential to initiate a distinct approach in predicting difficult laryngoscopy. By integrating these measurements with existing bedside tests, a substantial enhancement in the accuracy and robustness of predictive evaluations may be reached.