Pre- and Postdialysis Blood Pressures Are Imprecise Estimates of Interdialytic Ambulatory Blood Pressure

Abstract

H ypertension is perhaps one of the most pervasive problems of patients with ESRD. Although current guidelines that focus on cardiovascular disease in dialysis patients call for hypertension control as a top priority, the vast majority of patients who are on hemodialysis are hypertensive and control rates are poor (1). For practical reasons, BP assessment and antihypertensive treatment in patients with ESRD is performed on the basis of measurements that are made either immediately before or after dialysis. Such timehonored practice is widely accepted and formally recommended by clinical guidelines. The recent National Kidney Foundation Kidney Disease Outcomes Quality Initiative guidelines suggest that predialysis and postdialysis BP should be Ͻ140/90 and Ͻ130/80 mmHg, respectively (2).Population-based studies, including the recent Pressioni Arteriose Monitorate e Loro Associazioni (PAMELA) (3) and Ohasama studies (4) and studies on patients who had hypertension and were referred to a specialist clinic in the Dublin Outcome Study (5), have demonstrated clearly that ambulatory BP monitoring (ABPM) provides more accurate prognostic information than office BP, an issue that seems to be of particular relevance in the elderly. In a recent analysis of the ABPM substudy of the Systolic Hypertension in Europe (Syst-Eur) trial (6), ABPM and clinic BP did not identify the same patients for antihypertensive treatment, and ABPM was a better predictor of cardiovascular outcomes than clinic BP. These considerations are of relevance to patients with ESRD because uremia is a strong catalyst of the aging process and because patients with ESRD are older, with an average age of 60 yr.Given that the population with ESRD is elderly and the relationship between ABPM and cardiovascular outcomes and total mortality has scarcely been studied, we examined the magnitude of the difference between ABPM and pre/postdialysis BP. We hypothesized that if there were substantial differences, especially when differences between the two methods of measurements were unpredictable, then the two methods of measurement may have differing prognostic significance. The primary objective of this systematic analysis was to determine the magnitude of the difference and the variability in the difference between BP that is recorded in the dialysis environment, before and after the dialysis procedure, and ABPM that is performed simultaneously in the hemodialysis population. Materials and MethodsPublished studies that had reported paired ABP and pre/postdialysis BP in patients who were undergoing conventional three times a Published online ahead of print. Publication date available at www.cjasn.org.

Determinants of Left Ventricular Mass and Hypertrophy in Hemodialysis Patients Assessed by Cardiac Magnetic Resonance Imaging

“…Although measurement of BP before starting and immediately at the end of dialysis is highly variable, dependent on fluid volume status and the hemodynamic effects of dialysis, it remains the clinical standard. Twenty-four-hour ambulatory BP monitoring studies have confirmed these associations (24), but this method is not universally available, is time-consuming, and is uncomfortable for dialysis patients.…”

Diagnosing Hypertension by Intradialytic Blood Pressure Recordings

“…However, predialysis and postdialysis BP measurements are generally inaccurate estimates of ambulatory BP measurements (10). In the dialysis unit, BP measurements are obtained every 30 min during dialysis, primarily to ensure the hemodynamic stability of patients during treatment.…”

On Poor Agreement Between Dialysis Unit and Ambulatory Blood Pressures

“…Wide limits of agreement and heterogeneity between studies limit generalizability of conclusions among these patients. 2 In particular, the escalating disagreement with increasing stages of hypertension is a particular concern in the study by Liu and colleagues. 1 All too often, farreaching conclusions are made about BP control for the rest of the week based on these readings.…”

“…3 It is unfortunate that nephrologists in current North American practice are rarely present on site during outpatient renal dialysis, unlike their European or Japanese counterparts. The relative lack of "presence" of a nephrologist, along with limited reimbursement and scarcity of trained nursing staff may have contributed to the slow implementation of ABPM among dialysis patients in North America, despite its proven efficacy 2,4 and excellent acceptance of the procedure. 5 One interesting but perhaps less well-studied aspect of dialysis-derived BP readings is the relative correlation of predialysis or postdialysis values, independent of each other, with results obtained by ABPM.…”