Difficult intubation in acromegalic patients: incidence and predictability.

BACKGROUND: Previous studies have suggested that the incidence of difficult intubation in acromegalic patients is higher than in normal patients. However, these studies were retrospective and did not include preoperative assessment of the airways. The aims of this study were to determine the incidence of difficult intubation and to assess the usefulness of preoperative tests in predicting difficult laryngoscopy.

METHODS: One hundred twenty-eight consenting acromegalic patients requiring general anesthesia and tracheal intubation were studied. Preoperatively, Mallampati classification, thyromental distance, and head and neck movement were determined in each patient. After induction of anesthesia and muscle paralysis, laryngoscopic grade was assessed during direct laryngoscopy; Cormack and Lehane grade III or IV were classified as difficult. The association of individual airway assessment with laryngeal view was evaluated using the Fisher exact test. Predictors of difficult laryngoscopy were evaluated by calculating their sensitivity and specificity.

RESULTS: Laryngoscopy was difficult (grade III) in 33 of 128 patients (26%). Application of external laryngeal pressure improved laryngeal visualization to grade II in 20 of these 33 patients. In the remaining 13 patients (10%), intubation was difficult (more than two attempts, blade change, use of gum-elastic bougie). Mallampati classes 3 and 4 were significantly related to laryngoscopy grade III (Fisher exact test, P = 0.001).

CONCLUSIONS: The incidence of difficult laryngoscopy and intubation in acromegalic patients is higher than in normal patients. Preoperative Mallampati scores of 3 and 4 were of value in predicting difficult laryngoscopy. Nevertheless, even this test will miss a significant number of patients with a difficult airway.