Prevalence and prediction of difficult intubation in maxillofacial surgery patients

Abstract

Purpose: The failure to maintain a patent airway after the induction of general anesthesia is a major concern for anesthesiologists. For securing the airway, tracheal intubation using direct laryngoscopy remains the method of choice in most cases. However, direct laryngoscopic intubation is difficult in 1% to 4%, and impossible in 0.05% to 0.35%, of patients who have seemingly normal airways. This study sought to determine the prevalence of difficult intubation in maxillofacial surgery patients, and to evaluate the usefulness of various predictive tests for difficult intubation.

Patients and methods: This study was conducted on 208 patients undergoing maxillofacial surgery. During the preoperative visit, patients were examined in terms of the test of Mallampati et al (Can Anaesth Soc J 32:429, 1985), thyromental distance, sternomental distance, and interincisal distance. Direct laryngoscopic grading, as defined by Cormack and Lehane (Anesthesia 39:1105, 1984), was recorded for each patient. An intubation of "no difficulty" was noted when the tube was inserted into the fully visualized larynx with little effort on the first attempt.

Results: Intubation was possible in all patients. Combinations of different predictive tests resulted in higher sensitivity. Among all test types, that of Cormack and Lahene was thought to exhibit the highest sensitivity and positive predictive values when used alone. The prevalence of difficult intubation in our group of maxillofacial surgery patients was 15.4%. It may be concluded that a combination of predictive variables can be used to improve sensitivity.

Conclusions: We demonstrated that combining the Mallampati test with other instruments of measurement resulted in higher sensitivity than when either test was used alone.