The Evaluation of Predictability of Difficult Intubation Using Upper Lip Bite Test / 대한마취과학회지

BACKGROUND: The unexpected difficult endotracheal intubation is a significant contributor to mortality and morbidity in clinical practice. Although there are many methods to predict difficult intubation, modified Mallampati test (mMT) and airway score were popular tests. The authors wanted to compare upper lip bite test (ULBT) with those two tests and also explored the possibility that ULBT could be a good sole predictor for difficult intubation. METHODS: 322 patients who were ASA I or II, aged > 16yr were enrolled in this study. Three residents visited patients to obtain airway measurements such as 1) ULBT, 2) mMT, 3) airway score (inter-incisor gap, mMT, thyromental distance, head & neck movement, history of difficult intubation, buck teeth). They were not involved in the intubation of patients they evaluated. The accuracy, specificity, positive and negative predictive values were calculated from the data of three tests, and three tests were compared with patient's laryngoscopic view grade according to Cormack & Lehane criteria by using Chi-square test. RESULTS: The incidence of Cormack & Lehane grade III, IV was 14.6% (not applied external laryngeal pressure). ULBT showed significantly higher specificity, positive predictive value than mMT, but sensitivity was lower than other tests. There were significant correlations between ULBT class III and Cormack & Lehane laryngoscopic grade III, IV (P< 0.001). CONCLUSIONS: ULBT is good for predicting difficult intubation as a simple, single test. But because of it's low sensitivity, it seems better to incorporate ULBT as a factor of airway score tests for more reliable prediction.

Evaluation of Airway Assessment factors for Predicting difficult intubation / 대한마취과학회지

BACKGROUND: Endotracheal intubation is a common procedure in anesthesia, which can usually be accomplished easily. However, if the attempt is unexpectedly difficult the patient may be seriously at risk. If we can anticipate difficult intubation by assessing the airways in advance, anesthesiologists can plan the safest and most effective way of managing tracheal intubation. The purpose of this study is to evaluate a correlation between airway assessment factors and laryngoscopic grades for predicting difficult intubation. METHODS: The data were collected from a total of 427(male 189) patients older than 16 years of age undergoing non-emergency surgery. Seven airway assessment factors, measured at three levels of severity, were evaluated. Airway assessment factors include inter incisor gap, Samsoon and Young classification, thyromental distance, head and neck movement, body weight, history of difficult intubation and buck teeth. RESULTS: There was a significant correlation between total airway score and laryngoscopic grade. The incidence of difficult intubations was 9 out of 427 patients. Samsoon and Young classification, thyromental distance, head and neck movement, history of difficult intubation were significantly independent airway factors for predicting difficult intubations. Increase of total airway score represents the risk of difficult intubations. CONCLUSION: We suggest that total airway score could be used as a valuable predictor for assessing difficult intubations.