Treatment of hypertension in dialysis patients by ultrafiltration: role of cardiac dilatation and time factor

Does Renal Denervation a Reasonable Treatment Option in Hemodialysis-Dependent Patient with Resistant Hypertension? A Narrative Review

PURPOSE OF REVIEW

This narrative review aims to assess the pathophysiology, diagnosis, and treatment of resistant hypertension (RH) in end-stage kidney disease (ESKD) patients on dialysis, with a specific focus on the effect of renal denervation (RDN) on short-term and long-term blood pressure (BP) control. Additionally, we share our experience with the use of RDN in an amyloidotic patient undergoing hemodialysis with RH.

RECENT FINDINGS

High BP, an important modifiable cardiovascular risk factor, is often observed in patients in ESKD, despite the administration of multiple antihypertensive medications. However, in clinical practice, it remains challenging to identify RH patients on dialysis treatment because of the absence of specific definition for RH in this context. Moreover, the use of invasive approaches, such as RDN, to treat RH is limited by the exclusion of patients with reduced renal function (eGFR < 45 mL/min/1.73 m3) in the clinical trials. Nevertheless, recent studies have reported encouraging results regarding the effectiveness of RDN in stage 3 and 4 chronic kidney disease (CKD) and ESKD patients on dialysis, with reductions in BP of nearly up to 10 mmhg. Although multiple underlying pathophysiological mechanisms contribute to RH, the overactivation of the sympathetic nervous system in ESKD patients on dialysis plays a crucial role. The diagnosis of RH requires both confirmation of adherence to antihypertensive therapy and the presence of uncontrolled BP values by ambulatory BP monitoring or home BP monitoring. Treatment involves a combination of nonpharmacological approaches (such as dry weight reduction, sodium restriction, dialysate sodium concentration reduction, and exercise) and pharmacological treatments. A promising approach for managing of RH is based on catheter-based RDN, through radiofrequency, ultrasound, or alcohol infusion, directly targeting on sympathetic overactivity.

Resistant hypertension in dialysis

Hypertension is the most common finding in chronic kidney disease patients, with prevalence ranging from 60% to 90% depending on the stage and etiology of the disease. It is also a significant independent risk factor for cardiovascular disease, progression to end-stage kidney disease and mortality. According to the current guidelines, resistant hypertension is defined in the general population as uncontrolled blood pressure on three or more antihypertensive drugs in adequate doses or when patients are on four or more antihypertensive drug categories irrespective of the blood pressure control, providing that antihypertensive treatment included diuretics. The currently established definitions of resistant hypertension are not directly applicable to the end-stage kidney disease setting. The diagnosis of true resistant hypertension requires confirmation of adherence to therapy and confirmation of uncontrolled blood pressure values by ambulatory blood pressure measurement or home blood pressure measurement. In addition, the term "apparent treatment-resistant hypertension," defined as an uncontrolled blood pressure on three or more antihypertensive medication classes, or use of four or more medications regardless of blood pressure level was introduced. In this comprehensive review we focused on the definitions of hypertension, and therapeutic targets in patients on renal replacement therapy, including the limitations and biases. We discussed the issue of pathophysiology and assessment of blood pressure in the dialyzed population, management of resistant hypertension as well as available data on prevalence of apparent treatment-resistant hypertension in end-stage kidney disease. To conclude, larger sample-size and even higher quality studies about drug adherence should be conducted in the population of patients with the end-stage kidney disease who are on dialysis. It also should be determined how and when blood pressure should be measured in the group of dialysis patients. Additionally, it should be stated what the target blood pressure values in this group of patients really are. The definition of resistant hypertension in this group should be revisited, and its relationship to both subclinical and clinical endpoints should be established.

OUP accepted manuscript

Patients on chronic hemodialysis are counseled to reduce dietary sodium intake to limit their thirst and consequent interdialytic weight gain (IDWG), chronic volume overload and hypertension. Low-sodium dietary trials in hemodialysis are sparse and mostly indicate that dietary education and behavioral counseling are ineffective in reducing sodium intake and IDWG. Additional nutritional restrictions and numerous barriers further complicate dietary adherence. A low-sodium diet may also reduce tissue sodium, which is positively associated with hypertension and left ventricular hypertrophy. A potential alternative or complementary approach to dietary counseling is home delivery of low-sodium meals. Low-sodium meal delivery has demonstrated benefits in patients with hypertension and congestive heart failure but has not been explored or implemented in patients undergoing hemodialysis. The objective of this review is to summarize current strategies to improve volume overload and provide a rationale for low-sodium meal delivery as a novel method to reduce volume-dependent hypertension and tissue sodium accumulation while improving quality of life and other clinical outcomes in patients undergoing hemodialysis.

Pilot feasibility study examining the effects of a comprehensive volume reduction protocol on hydration status and blood pressure in hemodialysis patients

INTRODUCTION

Chronic volume overload is a persistent problem in hemodialysis (HD) patients. The purpose of this study was to investigate the impacts of comprehensive volume reduction protocol on HD patient's hydration status and blood pressure (BP).

METHODS

Twenty-three HD patients (age = 55.7 ± 13.3 years) completed a 6-month comprehensive volume control protocol consisting of: reducing postdialysis weight; reducing BP medication prescriptions; and weekly intradialytic counseling to reduce dietary sodium intake and interdialytic weight gain (IDWG). The primary outcome was volume overload (VO) measured by bioelectrical impedance spectroscopy. Secondary outcomes included: IDWG, postdialysis weight, estimated dry weight (EDW), dietary sodium intake, BP and BP medication prescriptions.

FINDINGS

From baseline (0M) to 6 months (6M), significant improvements were noted in: VO (0M 3.9 ± 3.9 L vs. 6M 2.6 ± 3.4 L, P = 0.003), postdialysis weight (0M 89.4 ± 23.1 kg vs. 6M 87.6 ± 22.2 kg; P = 0.012), and EDW (0M 89.0 ± 23.2 vs. 6M 86.7 ± 22.5 kg., P = 0.009). There was also a trend for a reduction in monthly averaged IDWG (P = 0.053), and sodium intake (0M 2.9 ± 1.6 vs. 6M 2.3 ± 1.1 g/d, P = 0.125). Neither systolic BP (0M 162 ± 27 vs. 6M 157 ± 23 mmHg, P = 0.405) nor diastolic BP (0M 82 ± 21 vs. 6M 82 ± 19 mmHg, P = 0.960) changed, though there was a significant reduction in the total number of BP medications prescribed (0M 3.0 ± 1.0 vs. 6M 1.5 ± 1.0 BP meds; P = 0.004).

DISCUSSION

Our volume reduction protocol significantly improved HD patient's hydration status. While BP did not change, the reduction in prescribed BP medication number suggests improved BP control. Despite these overall positive findings, the magnitude of change in most variables was modest. Comprehensive changes in HD clinics may be necessary to realize more clinically significant results.

Volume Control Associated with Better Cardiac Function in Long-Term Peritoneal Dialysis Patients

Background

This study was undertaken to investigate the effect of long-term blood pressure (BP) reduction, achieved with salt restriction and strict volume control, on frequency and regression of left ventricular hypertrophy (LVH) in long-term peritoneal dialysis (PD) patients.

Methods

56 patients who had been treated for more than 2 years under our care were enrolled. After echocardiographic (Echo) evaluation, 46 patients were included in the follow-up study. In our unit, we aim to keep patients’ BP below 130/85 mmHg and cardiothoracic index below 0.50. To reach these targets, moderate salt restriction is advised, and if necessary, hypertonic PD solutions are used. Echo was performed at the beginning of the study (after a mean period of 36 months on PD) and at the end of the prospective follow-up period (24 months later).

Results

At the time of the first Echo, LVH was detected in only 8 (21%) patients. Residual urine volume was significantly decreased compared to data taken when they first started PD (658 ± 795 vs 236 ± 307 mL/day). Mean left ventricular mass index (LVMI) was 107 ± 26.5 g/m2. LVMI was significantly decreased at the end of the follow-up in patients who had LVH at baseline. No LVH developed in patients who had normal LVMI at baseline.

Conclusion

Our results indicate that control of hypertension is possible when extracellular fluid volume is kept under control using hypertonic PD solutions in case of recruitment in addition to salt restriction in long-term PD patients. Sustained normovolemia is associated with low incidence and regression of LVH.

Hypertension in patients on dialysis: diagnosis, mechanisms, and management

Hypertension (blood pressure > 140/90 mm Hg) is very common in patients undergoing regular dialysis, with a prevalence of 70-80%, and only the minority has adequate blood pressure (BP) control. In contrast to the unclear association of predialytic BP recordings with cardiovascular mortality, prospective studies showed that interdialytic BP, recorded as home BP or by ambulatory blood pressure monitoring in hemodialysis patients, associates more closely with mortality and cardiovascular events. Although BP is measured frequently in the dialysis treatment environment, aspects related to the measurement technique traditionally employed may be unsatisfactory. Several other tools are now available and being used in clinical trials and in clinical practice to evaluate and treat elevated BP in chronic kidney disease (CKD) patients. While we wait for the ongoing review of the CKD Blood Pressure KIDGO guidelines, there is no guideline for the dialysis population addressing this important issue. Thus, the objective of this review is to provide a critical analysis of the information available on the epidemiology, pathogenic mechanisms, and the main pillars involved in the management of blood pressure in stage 5-D CKD, based on current knowledge.

Interplay of volume, blood pressure, organ ischemia, residual renal function, and diet: certainties and uncertainties with dialytic management

Extracellular fluid volume overload and its inevitable consequence, hypertension, increases cardiovascular mortality in the long term by leading to left ventricular hypertrophy, heart failure, and ischemic heart disease in dialysis patients. Unlike antihypertensive medications, a strict volume control strategy provides optimal blood pressure control without need for antihypertensive drugs. However, utilization of this strategy has remained limited because of several factors, including the absence of a gold standard method to assess volume status, difficulties in reducing extracellular fluid volume, and safety concerns associated with reduction of extracellular volume. These include intradialytic hypotension; ischemia of heart, brain, and gut; loss of residual renal function; and vascular access thrombosis. Comprehensibly, physicians are hesitant to follow strict volume control policy because of these safety concerns. Current data, however, suggest that a high ultrafiltration rate rather than the reduction in excess volume is related to these complications. Restriction of dietary salt intake, increased frequency, and/or duration of hemodialysis sessions or addition of temporary extra sessions during the process of gradually reducing postdialysis body weight in conventional hemodialysis and discontinuation of antihypertensive medications may prevent these complications. We believe that even if an unwanted effect occurs while gradually reaching euvolemia, this is likely to be counterbalanced by favorable cardiovascular outcomes such as regression of left ventricular hypertrophy, prevention of heart failure, and, ultimately, cardiovascular mortality as a result of the eventual achievement of normal extracellular fluid volume and blood pressure over the long term.

Modified Nutritional Recommendations to Improve Dietary Patterns and Outcomes in Hemodialysis Patients

The renal diet has traditionally been regarded as one of the most complex medical nutrition therapies to teach, understand, and implement. Specifically, patients are instructed to limit fruits, vegetables, nuts, legumes, dairy, and whole grains because of both phosphorus and potassium concerns. Furthermore, hemodialysis patients are often encouraged to decrease fluid intake to control interdialytic weight gain. These restrictions can result in frustration, lack of autonomy, and the perception that there is nothing left to eat. It is possible that the traditional renal diet may be liberalized, with a focus on whole foods low in sodium and phosphorus additives, to afford patients greater choices and ultimately improved outcomes. Therefore, the objective of this review is to concisely assess the evidence in support of a renal diet focused primarily on reducing the intake of sodium and inorganic phosphorus. Finally, the limited evidence for restrictions on dietary potassium intake is summarized.

Controversies and problems of volume control and hypertension in haemodialysis

Extracellular volume overload and hypertension are important contributors to the high risk of cardiovascular mortality in patients undergoing haemodialysis. Hypertension is present in more than 90% of patients at the initiation of haemodialysis and persists in more than two-thirds, despite use of several antihypertensive medications. High blood pressure is a risk factor for the development of left ventricular hypertrophy, heart failure, and mortality, although there are controversies with some study findings showing poor survival with low-but not high-blood pressure. The most frequent cause of hypertension in patients undergoing haemodialysis is volume overload, which is associated with poor cardiovascular outcomes itself independent of blood pressure. Although antihypertensive medications might not be successful to control blood pressure, extracellular volume reduction by persistent ultrafiltration and dietary salt restriction can produce favourable results with good blood pressure control. More frequent or longer haemodialysis can facilitate volume and blood pressure control. However, successful volume and blood pressure control is also possible in patients undergoing conventional haemodialysis.

Comparison of Turkish and US haemodialysis patient mortality rates: an observational cohort study

BACKGROUND

There are significant differences between countries in the mortality rates of haemodialysis (HD) patients. The extent of these differences and possible contributing factors are worthy of investigation.

METHODS

As of March 2009, all patients undergoing HD or haemodiafiltration for >3 months (n = 4041) in the Turkish clinics of the NephroCare network were enrolled. Data were prospectively collected for 2 years through the European Clinical Dialysis Database. Mean age ± standard deviation was 58.7 ± 14.7 years, 45.9% were female and 22.9% were diabetic. Comparison with US data was performed by applying an indirect standardization technique, using specific mortality rates for patients on HD by age, gender, race and primary diagnosis as provided by the 2012 US Renal Data System Annual Data Report as reference.

RESULTS

The crude mortality rate in Turkey was 95.1 per 1000 patient-years. Compared with the US reference population, the annual mortality rate for Turkey was significantly lower, irrespective of gender, age and diabetes. After adjustments for age, gender and diabetes, the mortality risk in the Turkish cohort was 50% lower than US whites [95% confidence interval (CI) 0.46-0.54, P < 0.001], 44% lower than US African-Americans (95% CI 0.52-0.61, P < 0.001) and 20% lower than Asian-Americans (95% CI 0.74-0.86, P < 0.05).

CONCLUSIONS

The annual mortality rate of prevalent HD patients was found to be significantly lower in the studied Turkish cohort compared with that published by the US Renal Data System Annual Data Report. Differences in practice patterns may contribute to the divergence.

Diastolic heart failure: a confusing concept

Descriptions of the pathophysiology of heart failure have gone through a substantial evolution in the last 50 years. It is now recognised that heart failure can occur in the presence and also in the absence of a reduction in left ventricular function. In the former situation, this classically has been described to lead to hypotension and secondary salt and volume retention by the kidneys, further aggravating cardiac function. In the latter, this has been described to lead to pulmonary congestion because of impaired cardiac diastolic filling. These concepts have further evolved in the discrimination of 'acute vascular' versus 'acute congestive' heart failure. The current paper builds the argument from numerous smaller observational studies that irrespective of the clinical presentation of heart failure, fluid congestion is the key. If left ventricular function is preserved, fluid retention is probably due to the inability of damaged kidneys to excrete the large amounts of salt ingested with modern diet. In the extreme of end-stage renal disease requiring haemodialysis, heart failure is frequent, but can be prevented almost entirely by strict volume control. Unfortunately, the absence of systematic studies describing fluid volumes and renal haemodynamic and reabsorptive function in patients with acute heart failure precludes the final proof of our concept. This paper therefore is a strong call for mechanistic research in this area.

Pharmacological and non-pharmacological treatment of hypertension in dialysis patients

Hypertension is very common in dialysis patients. The most important cause of hypertension is hypervolemia. Fluid restriction and volume management with standard hemodialysis are effective strategies to achieve dry weight and blood pressure control without use of antihypertensive drugs. If the captopril test is positive, a renin–angiotensin system blocker should be started. The pre-dialysis blood pressure goal in hemodialysis patients should be <140/90 mm Hg initially and <130/80 mm Hg at 3–6 months of dialysis.

Significance of interdialytic weight gain versus chronic volume overload: consensus opinion

Predialysis volume overload is the sum of interdialytic weight gain (IDWG) and residual postdialysis volume overload. It results mostly from failure to achieve an adequate volume status at the end of the dialysis session. Recent developments in bioimpedance spectroscopy and possibly relative plasma volume monitoring permit noninvasive volume status assessment in hemodialysis patients. A large proportion of patients have previously been shown to be chronically volume overloaded predialysis (defined as >15% above 'normal' extracellular fluid volume, equivalent to >2.5 liters on average), and to exhibit a more than twofold increased mortality risk. By contrast, the magnitude of the mortality risk associated with IDWG is much smaller and only evident with very large weight gains. Here we review the available evidence on volume overload and IDWG, and question the use of IDWG as an indicator of 'nonadherence' by describing its association with postdialysis volume depletion. We also demonstrate the relationship between IDWG, volume overload and predialysis serum sodium concentration, and comment on salt intake. Discriminating between volume overload and IDWG will likely lead to a more appropriate management of fluid withdrawal during dialysis. Consensually, the present authors agree that this discrimination should be among the primary goals for dialysis caretakers today. In consequence, we recommend objective measures of volume status beyond mere evaluations of IDWG.

Blood pressure and blood volume: acute and chronic considerations in hemodialysis

Hypertension is highly prevalent yet poorly controlled in the majority of dialysis patients and represents a significant burden of disease, with rates of morbidity and mortality greater than those in the general population. In dialysis, blood volume plays a critical role in the pathogenesis of hypertension, with expansion of extracellular volume increasingly recognized as an independent risk factor for morbidity and mortality. Within the current paradigm of dialysis prescription the majority of patients remain chronically volume expanded. However, management of blood pressure and volume state is difficult for clinicians with a paucity of randomized evidence adding to the complexity of nonlinear morbidity and mortality associations. With dialysis itself as a significant cardiac stressor, control of volume state is critical to minimize intradialytic hemodynamic instability, aid in preservation of cardiac anatomy and prevent progression to cardiovascular morbidity and mortality. This review explores the relationship of blood volume to blood pressure and potential targets for management in this at risk population.

Blood volume-monitored regulation of ultrafiltration in fluid-overloaded hemodialysis patients: study protocol for a randomized controlled trial

BACKGROUND

Data generated with the body composition monitor (BCM, Fresenius) show, based on bioimpedance technology, that chronic fluid overload in hemodialysis patients is associated with poor survival. However, removing excess fluid by lowering dry weight can be accompanied by intradialytic and postdialytic complications. Here, we aim at testing the hypothesis that, in comparison to conventional hemodialysis, blood volume-monitored regulation of ultrafiltration and dialysate conductivity (UCR) and/or regulation of ultrafiltration and temperature (UTR) will decrease complications when ultrafiltration volumes are systematically increased in fluid-overloaded hemodialysis patients.

METHODS/DESIGN

BCM measurements yield results on fluid overload (in liters), relative to extracellular water (ECW). In this prospective, multicenter, triple-arm, parallel-group, crossover, randomized, controlled clinical trial, we use BCM measurements, routinely introduced in our three maintenance hemodialysis centers shortly prior to the start of the study, to recruit sixty hemodialysis patients with fluid overload (defined as ≥15% ECW). Patients are randomized 1:1:1 into UCR, UTR and conventional hemodialysis groups. BCM-determined, 'final' dry weight is set to normohydration weight -7% of ECW postdialysis, and reached by reducing the previous dry weight, in steps of 0.1 kg per 10 kg body weight, during 12 hemodialysis sessions (one study phase). In case of intradialytic complications, dry weight reduction is decreased, according to a prespecified algorithm. A comparison of intra- and post-dialytic complications among study groups constitutes the primary endpoint. In addition, we will assess relative weight reduction, changes in residual renal function, quality of life measures, and predialysis levels of various laboratory parameters including C-reactive protein, troponin T, and N-terminal pro-B-type natriuretic peptide, before and after the first study phase (secondary outcome parameters).

DISCUSSION

Patients are not requested to revert to their initial degree of fluid overload after each study phase. Therefore, the crossover design of the present study merely serves the purpose of secondary endpoint evaluation, for example to determine patient choice of treatment modality. Previous studies on blood volume monitoring have yielded inconsistent results. Since we include only patients with BCM-determined fluid overload, we expect a benefit for all study participants, due to strict fluid management, which decreases the mortality risk of hemodialysis patients.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01416753.

Ultrafiltration Volume Is Associated with Changes in Blood Pressure in Chronically Hemodialyzed Patients

INTRODUCTION

Volume overload is a main factor in development of hypertension in hemodialysis patients. In order to demonstrate impact of ultrafiltration volume on blood pressure during 15-months period in a group of patients undergoing chronic hemodialysis therapy, we conducted this study. We hypothesized that ultrafiltration volume different affects the pre/postdialysis systolic pressure, diastolic pressure, mean arterial pressure (MAP), and pulse pressure (PP) values.

SUBJECTS AND METHODS

Study subjects were 23 anuric chronically hemodialyzed patients. The overall study time was 15 months, and 136 single hemodialysis treatments were analyzed.

RESULTS

Ultrafiltration was negatively correlated with predialysis systolic blood pressure (r = -0.169, p = 0.025), postdialysis systolic blood pressure (r = -0.292, p < 0.001), postdialysis MAP (r = -0.186, p = 0.015), predialysis PP (r = -0.290, p < 0.001), and postdialysis PP (r = -0.370, p < 0.001). Ultrafiltration/dry body mass (UF/W) ratio was negatively correlated with predialysis PP (r = -0.222, p = 0.005), postdialysis PP (r = -0.340, p < 0.001), and postdialysis systolic blood pressure (r = -0.243, p = 0.002). We found significant difference in postdialysis PP between dialyses with UF/W ratio < or = 0.05 an dialyses with UF/W ratio > 0.05 (63.49 +/- 20.76 vs. 56.27 +/- 16.33 mmHg, p = 0.033).

CONCLUSION

The ultrafiltration volume strongly affects postdialysis PP values. Evaluation of elevated blood pressure treatment in patients undergoing chronic hemodialysis therapy must be considered in respect of postdialysis PP values, not just depending on pre/postdialysis systolic and diastolic pressur or MAP values.

Effects of Low Sodium Dialysate in Chronic Hemodialysis Patients: An Echocardiographic Study

BACKGROUND

Chronic kidney disease (CKD) and hemodialysis (HD) patients who cannot restrict sodium consumption in their diets sometimes develop significant saline excess and hypertension between dialyses. This study assessed the effect of relatively low sodium dialysate dialysis on changes of echocardiography in hemodialysis patients.

METHODS AND RESULTS

Eighteen patients with end stage renal failure on chronic HD were studied (8 females, 10 males) with a mean age 48.3 +/- 14.6 (24-70) years. The mean time on HD was 30.8 +/- 14.0 (12-60) months. Patients with hematocrit levels under 24% were excluded from the study. In all patients, echocardiography was performed thrice weekly before and after eight-week HD treatment with low sodium dialysate hemodialysis by the same operator (135 mEq/L for patients with sodium levels less than 137, 137 for patients with sodium levels over 137). Left atrium (LA) and left ventricle (LV) volumes and ejection fractions were measured, specifically: LV systolic diameter (LVSD), LV diastolic diameter (LVDD), interventricular septum (IVS), tricuspid regurgitation (TR), mitral regurgitation (MR), pulmonary artery pressure (PAP), and inferior vein cava diameter (IVCD).

RESULTS

In terms of echocardiographic parameters, LVSD, TR, PAP, and IVCD were statistically decreased after low-sodium dialysate treatments (p = 0.002, 0.04, 0.013, and 0.00, respectively). Predialysis systolic and diastolic blood pressure (BP), post-dialysis systolic blood pressure, and interdialytic weight gain was statistically decreased when compared to basal levels (p = 0.00, p = 0.011, p = 0.022, p = 0.001, respectively).

CONCLUSION

A reduction of the dialysate sodium concentration based on the predialysis sodium levels of the patients could reduce the systolic BP and decrease the volume load on the heart as assessed by echocardiography. Within this short period, postdialysis diastolic BP could not be lowered. The effect of this approach should be studied in broad and lengthy series.

Blood volume monitoring to adjust dry weight in hypertensive pediatric hemodialysis patients

The aim of this study was to adjust dry weight by short-term blood volume monitoring (BVM)-guided ultrafiltration and evaluate the effects of optimizing dry weight on blood pressure (BP) control and intradialytic symptoms (IDS) in a group of hypertensive hemodialysis (HD) patients. The study was performed in four sequential phases, each of which lasted for 1 week, on nine hypertensive HD patients (six girls, age 16.9 +/- 3.1 years). In phase I, patients were observed by BVM. In phase II, BVM was used to guide ultrafiltration to adjust dry weight. Antihypertensive drugs were gradually tapered or withheld in phase III, when the patients were hypotensive and/or their IDS increased. In phase IV, this particular weight was maintained without any intervention. Pre- and post-HD body weight, pre-HD, post-HD, 30 min after HD casual BP values, and IDS in each HD session were recorded. The BP was also assessed by 44-h ambulatory BP monitoring (ABPM), which is an ideal method to determine BP changes throughout the interdialytic period at the beginning of phase I and at the end of phase IV. There was a decrease in mean dry weight, all casual systolic BPs, and systolic/diastolic ABPM at the end of the study (all p < or = 0.05). Antihypertensive drugs were stopped in five patients and reduced in two during phase III of the study. The IDS was more frequent (36%) in phase IV than in phase I (16%); however, this increase did not reach statistical significance. The results of this study suggest that short-term BVM guided-ultrafiltration may be a useful tool to diagnose volume overload and to adjust dry weight and, consequently, to achieve a better control of BP in pediatric HD patients.

Hypertension in children with chronic kidney disease: pathophysiology and management

Arterial hypertension is very common in children with all stages of chronic kidney disease (CKD). While fluid overload and activation of the renin-angiotensin system have long been recognized as crucial pathophysiological pathways, sympathetic hyperactivation, endothelial dysfunction and chronic hyperparathyroidism have more recently been identified as important factors contributing to CKD-associated hypertension. Moreover, several drugs commonly administered in CKD, such as erythropoietin, glucocorticoids and cyclosporine A, independently raise blood pressure in a dose-dependent fashion. Because of the deleterious consequences of hypertension on the progression of renal disease and cardiovascular outcomes, an active screening approach should be adapted in patients with all stages of CKD. Before one starts antihypertensive treatment, non-pharmacological options should be explored. In hemodialysis patients a low salt diet, low dialysate sodium and stricter dialysis towards dry weight can often achieve adequate blood pressure control. Angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers are first-line therapy for patients with proteinuria, due to their additional anti-proteinuric properties. Diuretics are a useful alternative for non-proteinuric patients or as an add-on to renin-angiotensin system blockade. Multiple drug therapy is often needed to maintain blood pressure below the 90th percentile target, but adequate blood pressure control is essential for better renal and cardiovascular long-term outcomes.

Fluid balance, dry weight, and blood pressure in dialysis

The total amount of sodium present in the body controls the extracellular volume. In advanced renal failure, sodium balance becomes positive and the extracellular volume expands. This leads to hypertension, and vascular changes that lead to adverse cardiovascular consequences in dialysis patients. Controlling the body sodium content and the extracellular volume allows one to better control hypertension and its consequences. This can be achieved by reducing the sodium input (sodium dietary restriction and reasonably low sodium dialysate) and/or by increasing the sodium output (ultrafiltration by convection). The discontinuous nature of hemodialysis causes saw-tooth volume fluctuations. This has led to the concept of dry weight (DW), a crucial component of dialysis adequacy. Assessment and achievement of DW is feasible on pure clinical grounds. But its relative lack of accuracy (and the physicians' progressive lack of interest in bedside examination) has led to several nonclinical methods of assessing DW in an effort to improve the assessment of fluid status in dialysis patients.

Audit of the effect of dialysate sodium concentration on inter-dialytic weight gains and blood pressure control in chronic haemodialysis patients

BACKGROUND/AIMS

Over the last three decades the standard dialysate sodium concentration has increased from 136 to 140 mmol/l (mEq/l) today. There has been great debate as to whether a reduction in dialysate sodium alone can lead to improved blood pressure control, and reduced inter-dialytic weight gain.

METHODS

An audit was performed in 469 maintenance regular haemodialysis patients who dialysed in seven different centres under the care of one university medical school.

RESULTS

Those centres which predominantly used a dialysate sodium of 140 mmol/l (mEq/l) had increased inter-dialytic weight gains, with more difficult blood pressure control, as not only did a greater percentage of patients require anti-hypertensive medication, but also more were prescribed multiple classes of anti-hypertensive agents. There was no difference in the frequency of symptomatic intra-dialytic hypotension.

CONCLUSIONS

A reduction in dialysate sodium was associated with lower inter-dialytic weight gains, without any additional intra-dialytic hypotensive episodes. Those patients in whom the difference between the time-averaged dialysate sodium concentration and the midweek pre-dialysis serum sodium was positive result had increased inter-dialytic weight gains, compared to those with a negative value. Reduced dialysate sodium alone was not effective in controlling blood pressure without additional proper dietary sodium restriction.

Dialysate composition and hemodialysis hypertension

Dialysis prescriptions have evolved to take advantage of new technology and serve a burgeoning patient population. High-sodium bicarbonate-based dialysate was first formulated in 1982 to enable short, safe, comfortable, high-efficiency hemodialysis (HD). Near-universal adaptation of these high-sodium formulas has virtually eliminated profound dialysis disequilibrium and greatly reduced dialysis discomfort, but has created a syndrome of dialysis salt loading with accentuated postdialysis thirst, interdialytic weight gain, and hypertension. Available technology will soon permit individuals to receive isonatremic dialysis with dialysate customized to the patient's serum sodium activity. Then, rather than choosing between comfortable, safe, high-efficiency dialysis with salt loading; cramps, asthenia, and symptomatic hypotension using low-sodium, high-efficiency rapid HD to control blood pressure (BP) and weight gain; or comfortable, slow, low-efficiency HD with BP control, physicians may be able to minimize symptoms and avoid dialysis salt loading while providing maximum time for rehabilitative activities. The current use of a single sodium activity for all patients ignores the inter- and intraindividual variability in serum sodium activity in our patients. This results in undesired consequences for 20-40% of patients. The application of even more severe salt loading through high-salt sodium modeling only accentuates the long-term problems of excessive thirst, weight gain, and hypertension.

HYPERTENSION IN HEMODIALYSIS PATIENTS: Dietary Sodium Restriction for Hypertension in Dialysis Patients

A close relationship between sodium and hypertension exists and this relationship is even more pronounced in renal failure and dialysis patients. Hypertension is one of the strongest predictors of poor outcome in dialysis patients. Almost all end-stage renal disease (ESRD) patients have hypertension and positive sodium balance, resulting in extracellular volume (ECV) expansion-the most important contributing factor to hypertension. Thus the effective management of hypertension requires normalization of the sodium balance and ECV. Two important methods to achieve this are limiting interdialytic weight gain (IDWG) and a dialysis process that is able to remove all IDWG and consistently attain dry weight. Since IDWG is directly dependent on sodium intake and the resulting thirst, sodium restriction is the most effective way to limit IDWG. Ultrafiltration and dialysate sodium concentration influence sodium removal, ECV control, and blood pressure (BP) control. Thus the dialysis session should be long enough to achieve dry weight and frequent enough to maintain appropriate BP.

Hypertension and cardiovascular risk assessment in dialysis patients

INTRODUCTION

Cardiovascular (CV) disease is the main cause of morbidity and mortality in dialysis patients. Hypertension in patients affected by chronic renal insufficiency (CRI) has been recognized as one of the major classical CV risk factors in CRI from the very beginning of the dialysis era. However, its treatment is still unsatisfactory.

METHODS

A discussion is employed to achieve a consensus on key points relating to the epidemiological, pathophysiological and clinical characteristics of hypertension in renal patients, in the light of global CV risk assessment.

RESULTS

CV disease is accelerated by CRI, in particular by uraemia-specific risk factors. This is reflected by the fact that general population-based equations for calculating CV risk underestimate the real CV risk in CRI and dialysis patients. Hypertension in dialysis patients is clearly a major CV risk factor. Isolated systolic hypertension with increased pulse pressure is the most prevalent blood pressure (BP) anomaly in dialysis patients, due to stiffening of the arterial tree. BP should be assessed by clinical measurements on a routine basis, leaving 24 h monitoring for selected cases. The targets of BP control should be those recommended by the present guidelines, i.e. <140/90 mmHg, or the lowest possible values that are well tolerated. The pathophysiological cornerstone of hypertension in dialysis patients is extra-cellular volume expansion, which is typically sodium-sensitive, given the loss of renal function. Therefore, the principles of hypertension treatment in dialysis are an achievement of dry body weight, proper dialysis prescription with respect to dialysis time and intra-dialytic sodium balance, and dietary sodium and water restriction. Pharmacological treatment should only be the second option, after the adequate and complete application of all other means. No comparative pharmacological trials have specifically addressed the issue of hypertension control in dialysis patients. Therefore, this workshop group had to rely largely on data obtained in the general population. Drugs interfering with the renin-angiotensin system were felt to be the first choice, as they have widely been shown to interfere significantly with CV remodelling. Despite long-standing concerns, beta-blockers are being used increasingly even in patients with congestive heart failure and ischaemic cardiomyopathy. Other drug classes may be used in association or as first-line agents according to clinical requirements.

CONCLUSIONS

Hypertension in renal patients has to be given particular and continued attention, and it should be adequately treated in light of the increased CV risk of this patient population. Research into the mechanisms of uraemic cardiomyopathy and cardiovascular remodelling should provide a precious new insight and lead to more precisely targeted and more effective therapies than in the past.

Mean arterial pressure and pulse pressure are associated with different clinical parameters in chronic haemodialysis patients

The mean arterial pressure (MAP) usually serves as an expression of blood pressure in patients on chronic haemodialysis (PCHD), instead of using solely systolic or diastolic pressure. Pulse pressure (PP) has been recognized as an important correlate of mortality in PCHD. We conducted this study in order to demonstrate clinical and biochemical determinants and variability of predialysis and postdialysis MAP and PP values. A total of 136 single haemodialysis (HD) treatments in 23 subjects (PCHD, 11 male and 12 female patients) were processed during 15 months. MAP before HD was in negative correlation with haemoglobin (P<0.001) and body mass index (BMI) (P<0.001), and in positive correlation with weekly erythropoietin dosage (P=0.017). MAP after HD was in negative correlation with haemoglobin (P<0.001), ultrafiltration per HD (P=0.015), and BMI (P=0.001), and in positive correlation with weekly erythropoietin dosage (P=0.003). PP before HD was in negative correlation with parathyroid hormone (PTH) level (P=0.020), haemoglobin (P<0.001), ultrafiltration per HD (P=0.001), and years on the chronic HD treatment (P=0.001), and in positive correlation with weekly erythropoietin dosage (P<0.001) and age (P<0.001). PP after HD was in significant negative correlation with PTH (P=0.015), haemoglobin (P=0.005), ultrafiltration per HD (P<0.001), BMI (P=0.003), and in positive correlation with weekly erythropoietin dosage (P<0.001) and age (P=0.004). Multiple regression analyses unveiled the strongest and negative correlations between MAP before HD and BMI (beta=-0.37, P=0.01); MAP after HD and haemoglobin (beta=-0.36, P=0.01); PP after HD and ultrafiltration/body weight ratio (beta=-0.41, P<0.001). The strongest and positive correlation was found between PP before HD and erythropoietin dosage per week (beta=0.51, P&<0.001). In conclusion, our findings support the assumption that PP and MAP are associated with different clinical parameters. PP values have advantages as the method of blood pressure expression.

Left ventricular mass and hemodynamic overload in normotensive hemodialysis patients

BACKGROUND

It remains uncertain whether the hemodynamic parameters are important determinants of left ventricular mass (LVM) in normotensive chronic hemodialysis (NTHD) patients, as has been found in their hypertensive counterparts.

METHODS

Forty NTHD patients (mean age, 53.7 +/- 14.4 years; male/female, 18/22) without the requirement of antihypertensive drugs for at least six months were studied. Controls were 41 hypertensive hemodialysis patients (HTHD) and 46 normotensive subjects with normal renal function (NTNR). The influence of anthropometrics, cardiovascular structure and function, and volume status on LVM (by two-dimensional echocardiography) was analyzed by steps of multiple linear regression.

RESULTS

As compared with the NTNR and NTHD group, the HTHD group had obvious pressure and volume/flow overload, and greater LV wall thickness, chamber size and mass. In contrast, NTHD subjects had similar blood pressure, large artery function, LV chamber size and stroke volume as the NTNR subjects. However, the NTHD patients still had greater wall thickness and LVM, along with greater cardiac output, lower total peripheral resistance and lower end-systolic meridional stress to volume ratio (ESSV) than the NTNR group. LVM in the NTHD group was significantly positively related to averaged systolic blood pressure (SBPavg), body surface area, extracellular fluid (ECF), carotid intima-media thickness (IMT), aortic pulse wave velocity (PWV), and negatively related to ESSV and Kt/V. The independent significant noncardiac structural determinants of LVM in NTHD subjects were ESSV, SBPavg, PWV and SV (model r2 = 0.617, P < 0.001).

CONCLUSIONS

The NTHD patients, without significant pressure and volume overload, still had increased LVM that was partially explained by the persistent flow overload and subclinical LV dysfunction.