Anthropometric measurements and research of difficult airway incidance during perioperative airway evoluation

The efficiency of pre-operative anthropometric measurements were compared with the Cormack-Lehane test in predicting the laryngoscopy difficulty among the patients who went general anesthesia at Akdeniz University Faculty of Medicine, Department of Anesthesiology. A total of 400 patients with a range of 18-75 years-old were included in this study. Age, height and weight of the study population were noted as the demographic values. Cormack-Lehane test was performed to each patient to detect the incidence of laryngoscopy difficulty. Mallampati test, upper lip bite test, the measurements of inter incisor gap, sternomental distance, thyromental distance, the length and circumference of the neck, the mandibular length and width were performed to all patients as the predictive tests in detecting the intubation difficulty. These tests were compared with the Cormack-Lehane classification that is a direct laryngoscopy test. The incidence of the laryngoscpy difficulty was 12.5 %. Among the demographic values, only body mass index showed statistically significant difference when the easy and difficult intubation groups were compared. When all the predictive laryngoscopy tests were compared with the Cormack-Lehane test, the length and circumference of the neck, Mallampati test and inter incisor gap showed statistically significant difference. Sternomental distance, thyromental distance, the length and width of the mandibula did not show any significant difference. ROC analyses showed the highest efficiency with the circumference of the neck and cut-off value was 41.8 cm. As a result, Mallampati classification which is used in pre-operative evaluation is helpful in detecting the easy laryngoscopy patients with high specificity and negative predictive values. All of the three tests were failed to predict the intubation difficulty with low sensitivity and specificity values. Thus the intubation difficulty depends on multiple factors, more than one test should be used together and the geographic variations should be considered.