Volume-associated ambulatory blood pressure patterns in hemodialysis patients

Although volume excess causes hypertension, whether it also affects circadian patterns of arterial pressures among hemodialysis patients remains unknown. To test the notion of whether volume overload is associated with a unique blood pressure (BP) "signature," a posthoc analysis was performed among 145 patients participating in the Dry-Weight Reduction in Hypertensive Hemodialysis Patients randomized, controlled trial. Using 400 ambulatory BP recordings over 8 weeks composed of 35 302 measurements, the trended cosinor model was found to be the best descriptor of BP chronobiology. The trended cosinor model may be described as a pattern of sinusoidal oscillation around a straight line with an upward trend during the interdialytic period that has an intercept at the postdialysis time. Augmented volume removal therapy reduced the intercept systolic BP and increased the rate of rise in systolic BP over the interdialytic interval but had no effect on the systolic BP fluctuation (amplitude). Thus, an elevated intercept and blunted slope pattern characterize the "volume-overload BP pattern" on ambulatory BP monitoring. Similar changes were seen for diastolic BP. Augmented volume removal therapy neither restored dipping nor was associated with a lag phenomenon for either the wake or the sleep systolic BP. Lowering of systolic BP was greater than diastolic BP such that pulse pressure was reduced. An observational cohort of 37 patients followed for 6 months confirmed these findings. Randomized trials are now needed to evaluate the clinical impact of augmented volume removal therapy on hard outcomes, because reduction of pulse pressure with this simple expedient has the potential to improve survival in hemodialysis patients.