Professor LEE Chul Hee at College of Medicine found that, for patients with obstructive sleep apnea, videofluoroscopy may help guide treatment by classifying the severity of the disorder and identifying the nature of the obstruction.

Compared with simple snorers, patients with obstructive sleep apnea had a more elongated and angled soft palate, with both changes becoming more pronounced with increasing severity, LEE reported in the February issue of Archives of Otolaryngology.

The changes were observed using videofluoroscopy, which provided a direct view of airway changes when the patient was awake and during medication-induced sleep states.

The technique"is an easy way to measure the soft palate changes and may be a useful technique to differentiate obstructive sleep apnea from simple snoring with short examination time," LEE said in the article.

In addition, sleep videofluoroscopy identified whether the soft palate, tongue base, or both were responsible for obstructing airflow. This information can help determine the most appropriate treatment, especially if surgery is required.

Other studies have evaluated techniques for providing a more exact diagnosis of obstructive sleep apnea, but most were conducted in patients who were awake.

Also, typically used techniques - including nasopharyngoscopy, pressure measurements, CT scanning, and MRI - generally produce static, nonmoving images, LEE said.

To get a direct, dynamic view of what was going on, LEE's team used sleep videofluoroscopy in 63 patients (50 men and 13 women; mean age 46) treated at a single center for suspected sleep apnea.

Following polysomnography, 53 patients were diagnosed with obstructive sleep apnea and 10 with simple snoring.

All also underwent videofluoroscopy before and after a short period of sleep induced by IV midazolam.

Desaturation sleep events - defined as a breathing interruption lasting 15 seconds or longer accompanied by a drop in blood oxygen saturation of at least 4% - occurred only in patients with obstructive sleep apnea.

Patients with the sleep disorder had significant changes in soft palate length (P<0.01) and in the angle between nasal floor and uvula tip (P<0.01) while awake and during normoxygenation and desaturation events.

The greatest changes occurred during desaturation events.

The increases in soft palate length became significantly greater the more severe the condition (P<0.05).

Simple snorers had small, nonsignificant changes in soft palate length and angle during normoxygenation events only.

During such events, changes in the soft palate were significantly larger in patients who had obstructive sleep apnea than in simple snorers (P<0.01 for length and P=0.03 for angle).

For sleep-disordered patients, sleep videofluoroscopy identified the reason for the obstruction as combination of the soft palate and tongue base in 43.5% of patients, the soft palate alone in 34%, and the tongue base alone in 22.5%.

LEE's team acknowledged some limitations of the study, including the fact that only selected sleep events were recorded, sleep staging was not scored, and sleep was drug-induced, which may not provide an accurate representation of physiologic sleep.

"Nevertheless, information from sleep videofluoroscopy might be helpful to determine the obstruction sites and the treatment option, such as surgery, continuous positive airway pressure treatment, or oral appliances," he said.

"And, if surgery is selected as a treatment," they said,"[videofluoroscopy] might also be used for quantitative comparison between pretreatment and post-treatment states of the upper airway."

Feb. 17, 2009
SNU PR Office