Determination of obstructive site in obstructive sleep apnea

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Abstract
Patients with obstructive sleep apnea syndrome (OSAS) may have airway obstruction at various levels, including the uvula-soft palate complex, base of tongue, and/or possibly other sites. For patients with tongue base and/or laryngeal obstruction, uvulopalatopharyngoplasty (UPPP, ppp) will not alleviate the obstruction. Prior authors have proposed that the hyoid bone position as determined by cephalometric x-rays can predict which patients have obstruction at a lower site than the soft palate. In this study, patients with obstructive sleep apnea syndrome were evaluated with polysomnographic testing, fiberoptic endoscopy, and cine-CT scans (Imatron Scanner with multiple level rapid sequence scans) in an attempt to determine precisely the site of airway obstruction. Measurements of airway size taken at the time of fiberoptic pharyngoscopy were compared with those determined by the cine-CT studies. Initial results revealed that fiberoptic pharyngoscopy in the sitting and supine positions was helpful in confirming pharyngeal airway sites with smaller diameters in awake patients. However, the cine-CT exam performed in both sleeping and awake states provided more direct data regarding the airway during sleep. We feel that with more clinical experience the cine-CT technique will prove to be the most helpful study for identification of the obstructive airway site in obstructive sleep apnea syndrome.