The purpose of this study is to explore the factors associated with interdialytic blood pressure variability in maintenance hemodialysis patients, especially the association between volume status and blood pressure variability.

Hemodialysis patients experience higher rates of cardiovascular morbidity and mortality than the general population and many populations with other chronic diseases. This exceptional risk is explained in part by known risk factors such as diabetes, hypertension, and other uremia-related factors, including vascular calcification and stiffness, autonomic dysfunction, and a high burden of circulating inflammatory mediators. However, additional unidentified risk factors also likely contribute to the disproportionately high prevalence of cardiovascular morbidity in hemodialysis patients. Blood pressure variability may represent one plausible cardiovascular risk factor. Data from nonuremic human populations show an association between greater blood pressure variability and cardiovascular events,nonfatal cardiovascular events,stroke,and increased left ventricular mass. There has been comparatively little work examining the causes and effects of blood pressure variability in hemodialysis populations. So the purpose of this study is to explore the factors associated with interdialytic blood pressure variability in maintenance hemodialysis patients, especially the association between volume status and blood pressure variability.

Inclusion Criteria:

• age 18 years or older
• receipt of thrice-weekly in-center hemodialysis
• no anticipation of imminent(<6 months)living related kidney transplant
• not transfer of care to a nonparticipating facility
• no dialytic modality change
• free of vascular, infectious, or bleeding complication within 1 month Exclusion Criteria:
• who missed >2 hemodialysis treatments over 1 month
• abused drugs
• severe anemia，malnutrition，chronic atrial fibrillation
• body mass index of 40 >kg/m2

hemodialysis patients of Beijing Chaoyang Hospital