Abstract:

Objective To explore the feasibility of ultrasonic measurement of the skin to hyoid bone distance, skin to epiglottis distance and skin to anterior commissure of vocal cords distance for predicting difficult laryngoscopy exposure in obstructive sleep apnea hypopnea syndrome(OSAHS) patients. Methods One hundred and fifty OSAHS patients with ASA Ⅰ-Ⅲ level, who underwent elective uvulopalatopharyngoplasty(UPPP) surgery under general anesthesia,were analyzed. Rountine airway assessment (Mallampati classification) and ultrasound measurement of the skin to hyoid bone distance, skin to epiglottis distance and skin to anterior commissure of vocal cords distance were performed before anesthesia. Intubation under direct laryngoscopy and the classification of laryngoscopy exposure was recorded. Cormack-Lehane classification Ⅲ-Ⅳ grade was defined as difficult laryngoscopy exposure. According to the classification results, patients were divided into two groups: non-difficult laryngoscopy exposure group and difficult laryngoscopy exposure group. We analyzed and compared the Malampati grading and ultrasound measurements between two groups. The receiver operating characteristic(ROC) curve and the optimal cut-off point of ultrasonic measurements were calculated. The effects of different methods for predicting difficult laryngoscopy exposure were analyzed. Results The proportion of cases whose Mallampati airway classification grade>Ⅱ in difficult laryngoscopy exposure group was significantly more than that in non-difficult laryngoscopy exposure group (P<0.05).The skin to hyoid bone distance and skin to epiglottis distance in difficult laryngoscopy exposure group were significantly longer than those in non-difficult laryngoscopy exposure group (P<0.05). The optimal cut-off point of the skin to hyoid bone distance and skin to epiglottis distance were 1.12 cm and 2.23 cm respectively. There was no significant difference in the skin to anterior commissure of vocal cords distance between two groups. Conclusion Ultrasound measurement of the skin to hyoid bone distance and skin to epiglottis distance had a good predictive value in difficult laryngoscopy exposure of the OSAHS patients.

Key words: Ultrasonic measurement, Difficult airway, Difficult laryngoscopy exposure, Obstructive sleep apnea hypopnea syndrome(OSAHS)