Prediction of difficult laryngeal exposure in patients undergoing microlaryngosurgery.

OBJECTIVES: Although difficult laryngeal exposure (DLE) is a common problem encountered during microlaryngosurgery, reliable predictors of DLE and grading systems of laryngeal exposure have been scarcely suggested in the field of laryngology. We propose a new classification of laryngeal exposure focusing on the extent of glottic visualization.
METHODS: We investigated physical parameters that could predict DLE; 73 patients underwent a physical examination including 15 parameters. During endotracheal intubation and suspension laryngoscopy, Cormack-Lehane and laryngeal exposure scores were obtained for each patient and compared with the parameters.
RESULTS: The patients' ages ranged from 23 to 77 years. The laryngeal exposure score was correlated with the Cormack-Lehane score (p < .001, r = 0.469). Of all parameters, body mass index, neck circumference, thyroid-mental distance, and horizontal thyroid-mental distance showed significant correlation with the laryngeal exposure score (p < .05). From analysis of the candidate parameters in 13 patients with DLE and the non-DLE group, we found that the cutoff values for predicting DLE were a body mass index of > 25.0 kg/m2, a neck circumference of > 39.5 cm, a thyroid-mental distance of < 5.5 cm, and a horizontal thyroid-mental distance of < 4.0 cm.
CONCLUSIONS: According to the proposed classification of laryngeal exposure, patients with obesity, a muscular neck, or retrognathia are likely to present DLE, and preoperative measurement of the predictors may be useful in preparing for microlaryngosurgery.