Prediction of difficult laryngeal exposure in patients undergoing microlaryngosurgery.

OBJECTIVE

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.