Abstract
Purpose
Drug-induced sleep endoscopy (DISE) is used to identify the site of obstruction causing obstructive sleep apnea (OSA). However, previous studies have reported a wide range of DISE findings, and new patterns of airway obstruction have also been observed during postoperative DISE. Therefore, we aimed to determine the features of changes in obstructive patterns during DISE.
Materials and Methods
Forty-two patients diagnosed with OSA underwent DISE for 25 min. Sites of obstruction were determined at the levels of the velum, lateral wall of the oropharynx, tongue base, and epiglottis. The velum obstruction configuration was classified as anteroposterior, lateral, or concentric.
Results
The obstructive pattern changed in 14 patients (33%). We observed a change in the site of obstruction in 9 patients (21.4%) and in the configuration of velum obstruction in 5 patients (11.9%). The changes occurred between 3 and 22 min after commencing DISE (mean, 10.6 ± 6.2 min). The proportion of obstructions in the velum, lateral wall of the oropharynx, and tongue base increased with longer DISE durations. The proportion of multiple-level obstructions increased significantly after 15 min ( P < 0.05). In the velum, anteroposterior obstructions in 2 patients and lateral obstructions in 3 patients changed into concentric obstructions. More configurations were observed with longer procedure durations.
Conclusions
Hence, we assume that it is possible to miss the site of obstruction during DISE if the procedure is too short, which may partly explain the discrepancies between studies.
1
Introduction
Drug-induced sleep endoscopy (DISE) is a useful method for identifying the site of obstruction causing obstructive sleep apnea (OSA), and its efficacy has been confirmed by several studies . DISE provides a direct 3-dimensional view of upper airway obstructions. Unlike other methods, such as cephalometry and Müller’s maneuver, DISE allows the clinician to evaluate the dynamic motion of the upper airway during sleep . Video fluoroscopy and multi-detector computed tomography are also acquired during drug-induced sleep, but video fluoroscopy only provides a view of 2-dimensional motion, and both methods are time-limited because of radiation exposure . DISE, on the other hand, shows upper airway obstruction in vivid motion and can be performed for longer durations without radiation exposure. Therefore, we conclude that DISE is the most useful method for determining the obstructive pattern in OSA.
DISE has been shown to have good (moderate-to-substantial) reliability . However, previous studies have reported varying results . For example, obstruction in the velum was reported in 63% of patients by Iwanaga et al. and in 100% of patients by Soares et al. . Furthermore, obstruction of the lateral wall of the oropharynx was reported in 7% of patients by Ravesloot et al. and in 51% of patients by George et al. . Discrepancies in results have also been observed at other sites. For example, obstructions at the tongue base varied from 34% in a study by Bachar et al. to 76.3% in that by Eichler et al. , and the obstruction at the level of the epiglottis varied from 9.6% in a study by Llatas et al. to 76% in that by Soares et al. .
We frequently observed that the site of obstruction changed depending on the duration of DISE. When DISE was performed for a short duration, changes in the site of obstruction were observed only in a few cases, but when it was performed for a longer duration, the changes increased. To date, no study assessed time-dependent changes in the patterns of airway obstructions during DISE. Therefore, the aim of our study was to determine the features of time-dependent changes in obstructive patterns during DISE.
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