Preoperative clinical prediction of difficult laryngeal exposure in suspension laryngoscopy

We investigated general and physical predictors of difficult laryngeal exposure in patients undergoing suspension laryngoscopy; 93 patients were included in this prospective study. The patients were classified as difficult laryngeal exposure group or non-difficult laryngeal exposure group based on the laryngeal view in suspension laryngoscopy. Twelve parameters (age, sex, body mass index, neck circumference, full mouth opening, modified mallampati index, hyoid-mental, thyroid-mental, horizontal thyroid-mental, vertical thyroid-mental, sternum-mental distance) that could predict difficult laryngeal exposure were evaluated. Of 93 patients, 22 had difficult laryngeal exposure. Cormack-Lehane score, neck circumference, body mass index, modified mallampati index, hyoid-mental, thyroid-mental, vertical thyroid-mental, and sternum-mental distance showed significant correlation with difficult laryngeal exposure. Based on the multivariate analysis, neck circumference superior to 40 cm, hyoid-mental and sternum-mental distance with respectively a value less than 6.05 and 13.9 cm were independently associated with difficult laryngeal exposure. Muscular neck, hyoid-mental and sterno-mental distance should be considered clinical predictors of difficult laryngeal exposure. Measurements of physical variables at full extension position of the neck are more useful and reliable predictors than neutral position for the risk of difficult laryngeal exposure.