Blood pressure variability is increasing from the first to the second day of the interdialytic interval in hemodialysis patients

Objectives: Patients with end-stage renal-disease under hemodialysis have increased cardiovascular risk and experience severe blood pressure (BP) fluctuations during the dialysis session and the subsequent interdialytic period. BP variability (BPV) may be an additional risk factor for cardiovascular events and preliminary data suggest increased BPV with advancing stages of chronic kidney disease. This is the first study to examine BPV during the whole intradialytic and interdialytic period in hemodialysis patients with ambulatory BP monitoring. Methods: A total of 160 patients receiving maintenance hemodialysis had 48-h ambulatory BP monitoring with the Mobil-O-Graph device during a regular dialysis session and the subsequent interdialytic interval. Brachial and aortic BPV were calculated with validated formulas and were compared between Days 1 and 2 of the interdialytic period (44-h), Days 1 and 2 of the total 48-h interval (including the dialysis session), and between the two respective daytime periods and night-time periods. Results: All brachial SBPV indices [SD: 14.75±4.38 vs. 15.91±4.41, P=0.001; weighted SD: 13.80±4.00 vs. 14.89±3.90, P<0.001; coefficient of variation (CV): 11.34±2.91 vs. 11.93±2.94, P=0.011; average real variability (ARV): 11.38±3.44 vs. 12.32±3.65, P<0.001)] were increasing from Days 1 to 2 of the 44-h interdialytic period. Similarly, all indexes of DBPV were significantly increased in Day 2, except for CV. Aortic SBPV and DBPV indices displayed a similar pattern. Furthermore, all studied brachial SBPV and DBPV indexes were also lower during daytimes 1 than 2 (systolic ARV 11.56±3.98 vs. 12.44±4.03, P=0.002); systolic ARV was lower in night-time 1 compared with night-time 2 (11.20±5.09 vs. 12.18±4.66, P=0.045). In multivariate regression analysis prehemodialysis SBP, age and diabetes were independently associated with increased SBP ARV. Conclusion: BPV is increased in interdialytic Day 2 compared with Day 1 in hemodialysis patients; this could be another mechanism involved in the complex cardiovascular pathophysiology and increased cardiovascular mortality of these individuals.