Drug-induced sleep endoscopy in the obstructive sleep apnea: comparison between NOHL and VOTE classifications

Obstructive sleep apnea (OSA) is characterized by recurrent episodes of partial or complete collapse of the pharynx that result in a decrease in oxyhemoglobin saturation. Nasofibrolaryngoscopy under induced sleep is a promising alternative for identifying sites of upper airway obstruction in patients with OSA. This study aimed to compare the obstruction sites screened by drug-induced sleep endoscopy (DISE) using the Nose oropharynx hypopharynx and larynx (NOHL) and Velum oropharynx tongue base epiglottis (VOTE) classifications. We also determined the relationship between OSA severity and the number of obstruction sites and compared the minimum SaO₂ levels between DISE and polysomnography (PSG). This was a prospective study in 45 patients with moderate and severe OSA using DISE with target-controlled infusion of propofol bispectral index (BIS) monitoring. The retropalatal region was the most frequent obstruction site, followed by the retrolingual region. Forty-two percent of patients had obstruction in the epiglottis. Concentrically shaped obstructions were more prevalent in both ratings. The relationship between OSA severity and number of obstruction sites was significant for the VOTE classification. Similar minimum SaO₂ values were observed in DISE and PSG. The VOTE classification was more comprehensive in the analysis of the epiglottis and pharynx by DISE and the relationship between OSA severity and number of affected sites was also established by VOTE. The use of BIS associated with DISE is a reliable tool for the assessment of OSA patients.