[Significance of apnea hypopnea time index in obstructive sleep apnea hypopnea syndrome patients and possible correlation between polysomnographic parameters and severity of the disease].

Objective: To find out the polysomnography (PSG) indexes that reflex the degree of pathology of obstructive sleep apnea hypopnea syndrome (OSAHS).

Methods: Six hundred and twenty-one male OSAHS patients, aged over 21, underwent measurement of weight, height, and neck circumference. Polysomnography was conducted to detect the apnea and hypopnea index (AHI), apnea and hypopnea time (AHT), and apnea and hypopnea time index (AHTI). A questionnaire survey based on Epworth sleep scaling (ESS) was conducted among 392 patients to assess the symptoms, such as excessive daytime sleepiness. 324 patients with an AHTI of 68.4 +/- 17.16 events/hour were regarded as severe group, and those with an AHTI >or= 7 events/hr were regarded as very severer group. The relationship among clinical characteristics and polysomnographic parameters were analyzed.

Results: The AHI, AHTI, and lowest SaO(2) of the patients were significantly correlated with the ESS7 scores, morning mouth dryness, daytime fatigue (all P < 0.01), and significantly correlated with sour regurgitation, and heartburn, (all P < 0.05). AHTI was significantly correlated (r = 0.317), morning mouth dryness (r = 0.239); and sour regurgitation, and heartburn (r = 0.137). AHT was significantly correlated (r = 0.344), morning mouth dryness (r = 0.261); and sour regurgitation, and heartburn (r = 0.138). Very significant differences existed in morning mouth dryness, sour regurgitation and heartburn, and ESS7 scores between the severe and very severe patients (all P < 0.01).

Conclusion: Among the PSG indexes, AHTI is better associated with sleepiness and other clinical symptoms than AHI. In severe OSAHS patients, there are significant differences in their clinical symptoms between the AHI < 70 events/hr group and AHI >or= 70 events/hr group.