Complete Palatal Obstruction on Drug-Induced Sleep Endoscopy: Just Mouth Breathing?

A 70-year-old obese male with moderate obstructive sleep apnea (OSA) sought alternative treatment after failing to tolerate positive airway pressure (PAP) therapy. He underwent drug-induced sleep endoscopy (DISE) with a nasal cannula and oral thermistor to differentiate nasal from oral breathing and a thoracoabdominal belt to track respiratory effort. DISE revealed a complete velum collapse in the anterior-posterior direction, consistent with his awake, supine computed tomography scan, yet the oral thermistor confirmed stable mouth breathing without respiratory distress. A mouth closure maneuver partially reopened the velum and appeared to enlarge the retroglossal airway. This case underscores the importance of evaluating a patient's primary breathing route during DISE, as standard interpretations of airway collapse may be misleading without this information. Mouth breathing may bypass obstructions at the velum, affecting PAP efficacy and influencing treatment decisions. To address this gap in the VOTE (velum, oropharyngeal lateral walls, tongue base, and epiglottis) classification system, we propose "VM" to denote velum collapse in the context of mouth breathing. This addition could aid in tailoring OSA treatments, particularly for patients who predominantly breathe orally. Our findings advocate for a more patient-specific approach to DISE interpretations, emphasizing the physiological and anatomical aspects of airway collapse.