OSAHS obstructive plane localization: comparative study between ag200 and friedman classification.

OBJECTIVE

To compare AG200 (Sleep Monitoring Obstructive Locator, Apneagraphy) and the result of Friedman classification and evaluate the accuracy of the two testing methods on OSAHS obstructive localization diagnosis.

METHODS

77 patients who were undergoing a treatment in the hospital, with Obstructive sleep apnea hypopnea syndrome (OSAHS) diagnosed by Polysomnography, were selected. Those patients were monitored by ArthroCare AG200 for their upper airway-esophageal pressure. Friedman classification, tongue height scale (Friedman tongue position, FTP), tonsil scale and classification between constituent ratio of upper obstruction ≥70% and constituent ratio of lower obstruction ≥70% were recorded before analyzing the relations of obstructive planes measured by Friedman classification and AG.

RESULT: Friedman clinical classification didn't include type IV patients (no patients had BMI ≥40, or had obvious jaw deformity); the comparison between each other within a group showed that the number of type III patients was apparently larger than that of Friedman type I (U=4.689, P<0.05); A common rule was that as the scale of Friedman classification and FTP increases, the lower obstructive constituent ratio also increases. AG systematic analysis showed that 66.23% (51/77) patients mainly complained of upper obstruction, i.e. upper obstructive constituent ratio ≥70% while 12.99% (10/77) patients mainly complained of lower obstruction, i.e. lower obstructive constituent ratio ≥70%). No obvious difference was detected if classified by tonsil size. If patients were classified by upper obstructive constituent ratio ≥70% and lower obstructive constituent ratio ≥70%, the condition of the patients, FTP and the size of the tonsil showed no significant difference (P>0.05).

CONCLUSION

Friedman classification method is easy to operate and to some extent, it can predict the site of obstructive plane, though the result is not always accurate because the result from Friedman classification of some patients was not consistent with that measured by nasopharyngo-fiberoscope and CT scan. Measuring the upper airway-esophageal pressure by AG200 system is the only localizing diagnosis method now to find the dynamic changes of all obstructive sites during the whole night as it can acquire the rough constituent ratio of obstructive plane and complement the shortcomings of physics examination and imaging tests. But it can only provide the location of the lowest plane instead of the accurate cause of obstruction and whether there is another obstruction above the existed obstruction at the same time. Clinically, patients, especially those who are considering surgeries like UPPP should combine different examination methods before the surgery so as to complement their advantages and improve the accuracy of localizing obstructive plane before deciding a proper surgery plan for a successful surgery, thus patients can recover as soon as possible.