[Research on the patterns of upper airway obstructive levels by drug-induced sleep endoscopy].

Objective: To identify the patterns of airway collapse in patients with obstructive sleep apnea hypopnea syndrome(OSAHS) by dexmedetomidine induced sleep endoscopy.

Methods: Forty-five obstructive sleep apnea patients diagnosed by polysomnography were given dexmedetomidine intravenously. Once the patient was sedated in dorsal position, the electronic nasopharyngoscope was inserted transnasally and positioned on five levels of the upper airway sequentially (velum, oropharyngeal lateral wall, tongue base, epiglottis and larynx) to observe and document the collapse. Each level should be observed no less than three apneas. The degree of airway narrowing was calculated by using the ImageTool. No obstruction was defined when the degree of airway narrowing <50%, and complete obstruction when ≥ 75%.

Results: In 45 patients with OSAHS, 1 case showed no obstruction on any level, 6 cases demonstrated obstructions on single level only, and 38 cases demonstrated complete obstructions on multilevel, including 17 cases with complete obstructions on two levels, 15 cases complete obstructions on three levels, and 6 cases complete obstructions on four levels. The patterns of collapse found in the trial were: (1) circumferential stricture by velum collapse was found in 43 patients, and 41 cases showed complete obstructions; (2) the side wall of oropharynx all collapsed in a lateral configuration, and 32 cases showed complete obstructions on this level; (3) anteroposterior swallowing tongue base was common, 11 cases showed partial obstructions on level of tongue base, and 10 cases complete; (4) epiglottic collapses occurred in lateral configuration folding as V shape; in anteroposterior configuration, epiglottis met posterior wall of the pharynx due to swallowing tongue base; the server soften epiglottis obstructed the entrance of the larynx, while the mild soften epiglottis and the collapsed side wall of pharynx came into being obstructions in concentric configuration; (5) the arytenoid area and aryepiglottic fold mucosa inwardly covered the glottis when the obstruction occurred in the larynx.

Conclusions: The patterns of hypopharynx obstructions in OSAHS patients are multifarious. Lateral oropharyngeal wall, epiglottic and tone base collapse play an important role in the obstructions. The laryngeal obstruction can also be observed.