Efficacy Assessment Of Continuous Positive Airway Pressure Therapy On 24-Hour Ambulatory Blood Pressure In Patients With Moderate To Severe Obstructive Sleep Apnea-Hypopnea Syndrome

Obstructive sleep apnea hypopnea syndrome(OSAHS) is a clinic syndrome charactered by repeated intermittent hypoxia during sleeping at night whether companied with hypercapnia or not. OSAHS can cause the damage of tissues, organs and systems, which has potential danger. OASHS can also cause hypertension, which increase the cardiovascular incident rate. At present continuous positive airway pressure is often used to treat OSAHS, but the efficacy evaluation was default. This article use the method of Cochrane to index and to screening the randomized controlled trials(RCTs), then we evaluate the difference of 24-hour ambulatory blood pressure, further to provide reliable reference for clinical rational therapy.Objective: To assess the impact of CPAP therapy on 24-hour ambulatory blood pressure in patients with moderate-severe OSAHS, and to evaluate the efficacy of this therapy.Methods: The following databases were searched: PubMed (1966-2007.5),EMBASE (1974-2007.5),Cochrane Library (1993-2007.5),Chinese Biomedical Literature Database (CBMWEB) (1978-2007.5 ),Chinese Scientific Journals Fulltext Database ( CSJD ) (1989-2007.5),China Journal Fulltext Database ( CJFD ) (1994-2007.5) et al; Web information of unpublished trials were searched by hand-searching reference lists and abstracts of conference proceedings and Google and Medical Martix; We also hand searched some important Chinese journals and tracked down the reference lists of papers related. Two reviews independently assessed the methodological quality of studies and extracted data. . RCTs and quasi randomized controlled trials (qRCTs) which adopted CPAP versus sham CPAP were included, to assessed the methodological quality of studies by randomization method, allocation concealment, blinding.RevMan 4.2.10 was used for meta-analysis. Studies of heterogeneity were estimated by random effects model, studies of no heterogeneity were estimated by fixed effects model, if the heterogeneity was caused by low quality studies, we would processed by sensitivity analysis.Dichotomous outcome results were expressed as relative risk (RR), continuous outcomes were expressed as weighted mean difference(WMD)and standard mean difference(SMD), both with 95% confidence intervals(CI).Results: Eight RCTs contains 429 patients were included. The Meta-analysis outcome showed that : mean daytime diastolic, 24-hour mean systolic, 24-hour mean blood pressure, nocturnal mean blood pressure, apnea hypopnea index(AHI) and the proportion which SaO₂ less than 90% happened during the total sleep time (SaO₂<90%, % of TST) were decreased in the group of CPAP, comparing with sham CPAP, the two groups existed statistical differences in these index. There was no statistical difference between them in mean daytime systolic, mean nighttime systolic, mean nighttime diastolic , 24-hour mean diastolic and diurnal mean blood pressure.Conclusion: The 24-hour ambulatory blood pressure was decreased in moderate-severe OSAHS after the treatment of CPAP , there were descent in mean daytime diastolic, 24-hour mean systolic, 24-hour mean blood pressure, nocturnal mean blood pressure, AHI and SaO₂<90%, % of TST. Owing to high possibility of selection bias and measurement bias in included studies, there must be negative impact on evidence intensity of the results, we expect best evidence with multicentre, large sample, and high quality prospective clinical studies.