OBJECTIVETo investigate the correlation between upper airway CT measurement value and severity of patients with obstructive sleep apnea hypopnea syndrome (OSAHS).

METHODSThe upper airway of 82 patients with OSAHS were scanned by CT during normal respiration. The 3-D CT measurement were made in lateral and anterior-posterior diameters, cross-section areas and volumes of retropalatal and retroglossal region.

RESULTSThe lateral diameters and cross-section areas of every research plane were negatively correlated with apnea and hypopnea index (AHI), in particular the minimal lateral diameter of the whole airway (r = -0.558, P < 0.01). For volumes, AHI decreased with larger volume of nasal cavity, nasopharyngeal cavity and velopharyngeal cavity (P < 0.05 or P < 0.01). The negative correlation between AHI and proportion of cavity volume to the bone frame of velopharyngeal area and whole upper airway were significant (P < 0.05 or P < 0.01). But the correlation between AHI and volume of velopharyngeal soft tissue, the proportion of soft tissue to the bone frame volume of velopharyngeal area, the proportion of soft tissue to the bone frame volume of whole upper airway was significant positive, as well as the correlation between AHI and the proportion of soft tissue to the cavity volume of velopharyngeal area and whole upper airway (P < 0.05 or P < 0.01).

CONCLUSIONSTo evaluate the severity of OSAHS with upper airway CT measurement, there is no difference between 3-D parameters and 2-D parameters. In terms of the whole airway, the lateral diameters, the cross-section area, the cavity volume, the soft tissue of the upper airway, are meaningful to evaluate the severity of disease, in particular the measurement of velopharyngeal area.