[Correlation study between obstructive level diagnosed by Apnea Graph and cephalometric posterior airway space in...

To study the correlation between Apnea Graph (AG) analysis of airway obstruction and cephalometric assessment of the posterior airway space in the diagnosis of obstructive level in patients with obstructive sleep apnea hypopnea syndrome (OSAHS), so as to improve the preoperative diagnostic accuracy and the therapeutic outcome.

Thirty patients (28 males and two females) who were diagnosed with severe OSAHS (mean AHI 58.6) by overnight polysomnography in recent 3 months were enrolled. The ages of the patients ranged from 35 to 59 years old with the median age of 41.5 years old. The mean body mass index (BMI, x(-) ± s) was (28.8 ± 4.1) kg/m(2). Mean apnea-hypopnea index (AHI) was (58.6 ± 16.4)/h. The lowest oxygen saturation was averaged to 0.69 ± 0.09. All patients underwent AG study as well as cephalometric analysis preoperatively. A correlation analysis was performed between the percentage of lower level obstructions measured by AG and the posterior airway space (PAS) evaluated by cephalometric analysis.

All of the 30 patients had the obvious narrow PAS of 4.4 - 10.8 mm, with the average of (7.6 ± 2.1) mm. Their constituent ratios of lower level obstruction ranged from 2 to 87 percent with the median ratio of 15.5% [9.0%; 35.8%]. Among all the patients, only 2 cases had more than 50 percent obstruction of the airway at lower level, 8 cases had 30 to 40 percent obstruction, and 6 cases had the narrow PAS less than 6 mm. The constituent ratio of lower level obstructions had a negative rectilinear correlation with the data of PAS (r = -0.6511, P < 0.01), which meant the patient with a higher percentage of lower obstruction had the tendency to have a corresponding narrower PAS. Two cases whose constituent ratios of lower level obstructions were not compatible with the rectilinear tendency due to tonsillar hypertrophy were reported.

AG analysis of airway obstruction and cephalometric assessment of the PAS could provide comparable and consistent results for the diagnosis of obstructive level in OSAHS. However, the tonsillar hypertrophy should be considered when using AG to identify the airway obstruction.