[The relationship between sleep episode and hypoxemia which following it in patients with obstructive sleep apnea-hypopnea syndrome and its clinical significance].

OBJECTIVE: To explore the relationship between sleep respiratory events and hypoxemia following obstructive sleep apnea-hypopnea syndrome (OSAHS) and its clinical significance. METHOD: Forty-five patients suffered from snoring and suspected of sleep breathing disorders were measured by a Chinese version of Epworth Sleepiness Scale and tested by polysomnography all night long. Some ordinary polysomnographic parameters were recorded in all cases as well as the delay period of desaturation which means the duration from the beginning of sleep respiratory events to the beginning of the following desaturation. RESULT: Forty-five patients were all suffered from obstructive sleep respiratory events. The mean delay period of desaturation in group of middle OSAHS was longer than that in group of normal snorers (P<0.05) as well as mild OSAHS (P<0.05). The mean delay period of desaturation in group of severe OSAHS was much longer than that in group of normal snorers (P<0.01) as well as mild OSAHS (P<0.01). But there is no significant difference between normal snorers and patients with mild OSAHS (P>0.05), and the difference between patients with middle OSAHS and patients with severe OSAHS as well (P>0.05). The mean delay period of desaturation had a positive relationship with AHI (r = 0.608, P<0.01) and a negative relationship with lowest SaO2 (LSaO2) (r = - 0.543, P<0.01). The relationship between total scores of the 7 questions of Epworth sleepiness scale (ESS7) with the mean delay period of desaturation (r = 0.689, P<0.01) was significantly higher than that with AHI and LSaO2 (r = 0.486, P<0.01; r = - 0.422, P<0.01). CONCLUSION: The delay period of desaturation is a sensitive parameter which describe oxygen desaturation following obstructive sleep respiratory events. The mean delay period of desaturation in group of middle and severe OSAHS was much longer than that in group of normal snorers as well as mild OSAHS. Furthermore, the mean delay period of desaturation has a closely relationship with AHI and LSaO2. And it was highly associated with ESS7 than AHI and LSaO2. Based on it, the mean delay period of desaturation may provide valuable information in evaluating the severity of the patients with OSAHS. It may evaluate the severity of daytime sleepiness better than AHI and LSaO2.