Prediction of Epiglottic Collapse in Obstructive Sleep Apnea Patients: Epiglottic Length

I-Chun Kuo,1,2 Li-Jen Hsin,1,2 Li-Ang Lee,1,2 Tuan-Jen Fang,1,2 Ming-Shao Tsai,2,3 Yi-Chan Lee,2,4 Shih-Chieh Shen,2,5 Hsueh-Yu Li1,2 1Departments of Otolaryngology-Head & Neck Surgery, Chang Gung Memorial Hospital, Linkou Main Branch, Tao-yuan City, Taiwan; 2College of Medicine, Chang Gung University, Tao-Yuan, Taiwan; 3Departments of Otolaryngology-Head & Neck Surgery, Chang Gung Memorial Hospital, Chiayi Branch, Chiayi City, Taiwan; 4Departments of Otolaryngology-Head & Neck Surgery, Chang Gung Memorial Hospital, Keelung Branch, Keelung City, Taiwan; 5Departments of Otolaryngology-Head & Neck Surgery, New Taipei City Municipal Tucheng Hospital, New Taipei City, TaiwanCorrespondence: Hsueh-Yu LiDepartments of Otolaryngology-Head & Neck Surgery, Chang Gung Memorial Hospital, Linkou Main Branch, Tao-yuan City, TaiwanTel +886-3-328-1200 ext.3966Fax +886-3-397-9361Email hily38@cgmh.org.twObjective: This study aims to explore the factors that contribute to epiglottic collapse (EC) in patients with obstructive sleep apnea (OSA).Methods: This study enrolled 35 patients (34 males; median age, 39 years; median apnea–hypopnea index (AHI), 55.4 events/h; median body mass index (BMI), 26.9 kg/m2). EC (epiglottis attaching onto the posterior pharyngeal wall) was diagnosed by drug-induced sleep computed tomography (DI-SCT). Three dimensions were assessed for comparison between the EC and non-EC (NEC) groups that included anatomical measurement: epiglottic length and angle, endoscopic classification of epiglottis obstructing the glottis (Type I, none; Type II, partial; and Type III, total), and dynamic hyoid movement during DI-SCT (Δ hyoid = √(x2 + y2), maximal displacement of hyoid in x and y axes during sleep breathing cycle).Results: EC was found in 12 patients (34%). No difference in age, gender, AHI, and BMI between the two groups was noted. The anatomical measurement revealed that epiglottis length was significantly different between the EC and NEC groups (21.2 vs 15.8 mm; p < 0.001), with a cutoff value of 16.6 mm (sensitivity, 100%; specificity, 65.2%). The EC group patients showed larger hyoid movement than the NEC group patients (Δ hyoid, 4.8 vs 3.0 mm; p = 0.027). By contrast, epiglottic angle and endoscopic classification revealed an insignificant difference between the two groups.Conclusion: Epiglottis is a potential collapse site among multilevel obstruction in moderate to severe OSA patients. Epiglottic length is highly sensitive in predicting EC, with the cutoff value of 16.6 mm. Hyoid movement plays a role in contributing to EC in OSA patients.Keywords: obstructive sleep apnea, epiglottic collapse, drug-induced sleep computed tomography, epiglottic length, hyoid bone movement