Upper airway collapse characteristics in adult patients with OSA and previous tonsillectomy.

Abstract

To analyze upper airway (UA) collapse patterns through drug-induced sleep endoscopy (DISE) in adult patients withobstructive sleep apnea (OSA) who previously underwent tonsillectomy. This was a retrospective study on patients withOSA who underwent DISE between June 1, 2013 and July 30, 2017 at Stanford Hospital. Subjects who had prior tonsillectomy history were classified into the tonsil0 group, whereas others were classified into the tonsil1 and tonsil2/3/4 group based on tonsil grade. UA collapse characteristics were recorded and analyzed among groups according to Velum, Oropharynx, Tongue base and Epiglottis (VOTE) classification. A total of 205 individuals were included, 38 in tonsil0 group, 104 in tonsil1 and 63 in tonsil2/3/4. The tonsil0 group had a higher percentage of anterior-posterior (AP) velum (58%) and tongue base (45%) collapse compared with the tonsil2/3/4 group (22%, P = 0.0003 and 22%, P = 0.02, respectively) but less oropharyngeal lateral wall collapses (29% vs 53%, P = 0.02). Most of the tonsil0 group (70%) showed multi-sites collapse pattern, the percentage of combined obstruction in both palatopharyngeal and hypopharyngeal region was higher (50% vs 29%, P = 0.03). The difference of velum complete AP collapse remained significant after adjusting for age and BMI (Odds Ratio = 0.33, 95% CI 0.12-0.86, P = 0.02). No significant differences were found between the tonsil0 and tonsil1 groups. Compared with individuals with larger tonsils (grade 2 to 4), those with previous tonsillectomy and OSA were susceptible to the velum AP configuration collapse. Diversity of multi-sites obstruction and combined collapse in both palatopharyngeal and hypopharyngeal level was the main characteristic.