Background: Limited mandibular condylar mobility plays an important role in difficult laryngoscopy. Indirect assessment methods, such as mouth opening, have been proven to be useful predictors of difficult laryngoscopy. Sonography is a new direct assessment method for the limited mandibular condylar mobility. However, whether this method could be used in predicting difficult laryngoscopy still remains unknown. This study aimed to observe its ability to predict difficult laryngoscopy.
Methods: Adult patients who were administered tracheal intubations for elective surgery under general anesthesia were enrolled in the study. Mandibular condylar mobility was assessed by sonography through condylar translation measurements. Beside mouth opening, other indirect variables that correlated with temporomandibular joint mobility, such as mandibular protrusion distance, upper lip bite test, and whether the condyle-tragus distance was <1 finger breadth, were also evaluated before anesthesia. The primary outcome was difficult laryngoscopy defined as the Cormack-Lehane level 3 or 4.
Results: A total of 484 patients were prospectively included, and difficult laryngoscopy was reported in 41 patients. The condylar translation prediction criterion for difficult laryngoscopy was ≤10 mm. The condylar translation was correlated with Cormack-Lehane level (Spearman correlation coefficient, -0.46; 99% confidence interval [CI], -0.55 to -0.36) and owned the highest area under the receiver operating characteristic curve (0.93; 99% CI, 0.90 to 0.96, compared with that of the other predictors, P < .001) with difficult laryngoscopy. The condylar translation ≤10 mm was with a considerable κ value (κ = 0.52; 99% CI, 0.37 to 0.67) to difficult laryngoscopy and proved to be an independent predictor by a multivariate logistic regression.
Conclusions: Compared with indirect assessments, such as mouth opening and other parameters, mandibular condylar mobility, as assessed directly using sonography, was correlated with difficult laryngoscopy and demonstrated an independent and notably predictive property.