Postdialysis blood pressure rise predicts long-term outcomes in chronic hemodialysis patients: a four-year prospective observational cohort study

Chih-Yu Yang,Yao-Ping Lin,Wu-Chang Yang

doi:10.1186/1471-2369-13-12

Abstract

BackgroundThe blood pressure (BP) of a proportion of chronic hemodialysis (HD) patients rises after HD. We investigated the influence of postdialysis BP rise on long-term outcomes.MethodsA total of 115 prevalent HD patients were enrolled. Because of the fluctuating nature of predialysis and postdialysis BP, systolic BP (SBP) and diastolic BP before and after HD were recorded from 25 consecutive HD sessions during a 2-month period. Patients were followed for 4 years or until death or withdrawal.ResultsKaplan-Meier estimates revealed that patients with average postdialysis SBP rise of more than 5 mmHg were at the highest risk of both cardiovascular and all-cause mortality as compared to those with an average postdialysis SBP change between -5 to 5 mmHg and those with an average postdialysis SBP drop of more than 5 mmHg. Furthermore, multivariate Cox regression analysis indicated that both postdialysis SBP rise of more than 5 mmHg (HR, 3.925 [95% CI, 1.410-10.846], p = 0.008) and high cardiothoracic (CT) ratio of more than 50% (HR, 7.560 [95% CI, 2.048-27.912], p = 0.002) independently predicted all-cause mortality. We also found that patients with an average postdialysis SBP rise were associated with subclinical volume overload, as evidenced by the significantly higher CT ratio (p = 0.008).ConclusionsA postdialysis SBP rise in HD patients independently predicted 4-year cardiovascular and all-cause mortality. Considering postdialysis SBP rise was associated with higher CT ratio, intensive evaluation of cardiac and volume status should be performed in patients with postdialysis SBP rise.

Highlights

The blood pressure (BP) of a proportion of chronic hemodialysis (HD) patients rises after HD
We categorized our patients into 3 groups, including patients with an average postdialysis systolic BP (SBP) rise of more than 5 mmHg (n = 39), those with an average postdialysis SBP change between -5 to 5 mmHg (n = 27), and those with an average postdialysis SBP drop of more than 5 mmHg (n = 49)
We examined the relationship between peridialysis BP alterations and outcomes, which revealed that patients with an average postdialysis SBP rise of more than 5 mmHg were more likely to suffer from 4-year cardiovascular and all-cause mortality

Summary

Introduction

The blood pressure (BP) of a proportion of chronic hemodialysis (HD) patients rises after HD. Due to oliguria or even anuria, most end-stage renal disease (ESRD) patients undergoing maintenance hemodialysis (HD) require ultrafiltration during HD in order to maintain a euvolemic status. The volumedependent component of hypertension may be corrected by fluid removal, a proportion of HD patients experience postdialysis BP rise. The underlying mechanisms of intradialytic hypertension are complex and have been considered to be caused by clinically silent fluid overload, activation of the renin-angiotensin axis, sympathetic overactivity, endothelial dysfunction, and sodium. Cardiovascular disease is the leading cause of morbidity and mortality in ESRD [10]. Hypertension is highly prevalent in patients undergoing HD and contributes to the high cardiovascular morbidity and mortality in these patients [11]. The predictive values of predialysis and postdialysis BP have been disputed due to its high variability nature [14,15,16], which could be overcome by increasing the number of BP recording times for more than 1 month [17,18]

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