Hypertension in hemodialysis patients

Body weight telemetry is useful to reduce interdialytic weight gain in patients with end-stage renal failure on hemodialysis

Lacking compliance with liquid intake restrictions is one of the major problems in patients on hemodialysis and causes an increased mortality. In 120 patients on hemodialysis with an average interdialytic weight gain (IWG) exceeding 1.5 kg on at least 2 days during the 4 weeks preceding the intervention, the effect of telemetric body weight measurement (TBWM) on IWG, ultrafiltration rate, and blood pressure was evaluated over a period of 3 months. Patients of the telemetric group (TG) were supplied with automatic scales, which transferred the weight via telemetry on a daily basis. In the case of IWG of more than 0.75 kg/24 h, a telephonic contact was made as required, and in the case of an IWG of more than 1.5 kg, telephonic contacting was obligatory along with the advice of a liquid intake restriction to 0.5 L/day until the next dialysis. The patients of the control group (CG) received standard treatment without telemetric monitoring. We examined specific data of the second interdialytic interval (IDI2) and the average within 1 week. The average difference of IWG between TG and CG was not significant before the start of the study but 0.2 kg (p=0.027) (IDI2)/0.27kg (p=0.001) (WP) at the end of the study, respectively. The average difference in the ultrafiltration rate within 1 week was 19.0 mL/h (p=0.282) (IDI2)/8.2 mL/h (p=0.409) before the start of the study but 28.4 mL/h (p=0.122) (IDI2)/30.9 mL/h (p=0.004) at the end of the study, respectively. Thus, TBWM is a feasible method for optimizing the IWG and reducing the ultrafiltration rate.

The relationship between chronic volume overload and elevated blood pressure in hemodialysis patients: use of bioimpedance provides a different perspective from echocardiography and biomarker methodologies

BACKGROUND

Chronic volume overload is very frequent in hemodialysis (HD) patients and is directly associated with hypertension, increased arterial stiffness, left ventricular hypertrophy (LVH), heart failure and ultimately with higher mortality and morbidity. One major issue is that presently there are very few comparative studies of the various methods (clinical, bioimpedance, inferior cava vein diameter (ICV) and Brain Natriuretic Peptide (NT-proBNP)) for volume status evaluation and their correlation with cardiovascular disease.

METHODS

In 160 patients treated by chronic HD in our center, euvolemic according to clinical assessment, we performed evaluation of volume status through bioimpedance spectroscopy (BIS), ICV and NT-proBNP, as well as echocardiography, to estimate the left ventricle structure and function.

RESULTS

Despite appearing clinically euvolemic, severe fluid overload, as defined by a relative tissue hydration (RTH)--i.e. fluid overload over extracellular water ratio (FO/ECW)--above 15% was found in 25.6% of patients. Four categories of patients were considered according to pre-HD BP and BIS values. Forty-five percent of patients (group A) had a reasonable control of BP and volume (SBP < 150 mmHg and RTH < 15%), 29.3% (group B) were classified as hypertensive (SBP > 150 mmHg and RTH < 15%), 16.7% (group C) had high blood pressure and marked volume expansion, (SBP > 150 mmHg and RTH > 15%), while 9% (group D) had SBP < 150 mmHg despite RTH > 15%. Assuming that BIS is the most accurate and validated method to assess hydration status, we calculated the positive predictive value for ICV-based evaluation--18%, with a sensitivity of 67% and an important proportion of false negative cases (45%). NT-proBNP was even less accurate: PPV of only 26%, with a sensitivity of 60% and a specificity of only 45% and an extremely high proportion of false positive cases (73%). Group A patients had the best cardio-vascular profile: lowest LV mass and NT-proBNP levels.

CONCLUSION

Using multi-frequency body impedance spectroscopy, we found a large group of hypertensive and/or fluid-overloaded patients despite apparently being at "dry weight" on clinical evaluation and a marked discrepancy between clinical appearance and fluid status. Of the 4 different methods, assuming BCM "gold standard", there were major disagreements and discrepancies between the other three methodologies. BCM is a valuable and simple bed-side tool for the correct management of BP and risk stratification in HD patients as it allows for excellent discriminators of more abnormal cardiac and vascular profiles.

Do restless legs syndrome (RLS) and periodic limb movements of sleep (PLMS) play a role in nocturnal hypertension and increased cardiovascular risk of renally impaired patients?

Hypertension can cause or promote renal failure and is related to cardiovascular mortality, the major cause of death in patients with renal impairment. Changes in the circadian BP pattern, particularly the blunting or reversal of the nocturnal decline in BP, are common in chronic renal failure. These changes in turn are among the major determinants of left ventricular hypertrophy. Using a chronobiological approach, it is possible to obtain better insight into the reciprocal relationship between hypertension, renal disease, and increased cardiovascular risk of renal patients. Disruption of the normal circadian rhythm of rest/activity may be hypothesized to underlie the high cardiovascular morbidity and mortality of such patients. Epidemiological studies reveal that hemodialysis patients experience poor subjective sleep quality and insomnia and, in comparison to healthy persons, are more likely to show shorter sleep duration and lower sleep efficiency. Sleep apnea may be present and is usually investigated in these patients; however, the prevalence of restless legs syndrome (RLS), which is high in dialysis patients and which has been associated with increased risk for cardiovascular disease in the general population, could also play a role in the pathogenesis of sleep-time hypertension in renal patients. Careful assessment of sleep quality, in particular, diagnostic screening for RLS and periodic limb movements (PLM) in renal patients, is highly recommended. In renal failure, attention to sleep quality and related perturbations of the sleep/wake cycle may help prevent the occurrence and progression of cardiovascular disease.

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.

Comparison of unilateral renal artery embolization versus bilateral for treatment of severe refractory hypertension in hemodialysis patients

OBJECTIVE

Hypertension in ESRD patients is common, and often refractory to common medical interventions. Bilateral renal embolization (BRE) is an alternative to nephrectomy in treating severe refractory hypertension in hemodialysis patients, but has drawbacks in residual renal function preservation and post-infarction syndrome. We evaluated the efficacy and safety of unilateral renal embolization (URE) for the treatment of severe refractory hypertension in hemodialysis patients.

PATIENTS AND METHODS

From January 2000 to May 2007, 16 hemodialysis patients with severe refractory hypertension were randomized to URE or BRE group, and received percutaneous transcatheter unilateral or bilateral renal embolization, respectively. The efficacy and complications of these two procedures were compared. The plasma renin activity (PRA), plasma angiotensin II, aldosterone and endothelin-1 (ET-1) were measured pre- and post-renal embolization in both groups.

RESULTS

The procedures were completed successfully without severe immediate complications. The blood pressure decreased from 211/122 to 127/81 mmHg in URE group (P < 0.0001), and in BRE group from 208/117 to 124/76 mmHg (P < 0.0001) with significantly reduced need for antihypertensive medications. The residual renal function was reasonably kept and post-infarction syndrome was milder in URE group compared with BRE group. No activation of RAS was observed in this series and no RAS activity dynamic change occurred post-procedure. Decreased circulating ET-1 was accompanied with the lowering of blood pressure after the procedure (P < 0.0001).

CONCLUSIONS

Unilateral renal embolization is as effective as BRE in treating severe refractory hypertension in hemodialysis patients, with advantages over BRE in residual renal function preservation and milder post-infarction syndrome.

Influence of haemodialysis on early markers of atherosclerosis

INTRODUCTION

End-stage renal disease (ESRD) patients treated by haemodialysis (HD) have impaired endothelium-dependent vasodilatation and increased intima-media thickness (IMT) of the carotid artery The aim of the study was to analyse the relationships between parameters of chronic HD treatment and non-invasive assessments of preclinical atherosclerosis (endothelial dysfunction and carotid IMT) in ESRD patients on HD.

METHODS

Fifty-two (19 females, 33 males) adult patients on chronic maintenance (4.65 +/- 3.29 years) HD aged 59.88 +/- 15.49 years were investigated. Ultrasonographic studies were performed with a 7.5 MHz high-resolution probe. The common carotid artery IMT was measured. Brachial artery diameter was analysed to the rest. In order to assess flow-mediated dilatation (FMD), hyperaemia was induced by a pneumatic cuff, and an analysis of the diameter was performed 1, 2, 3 and 4 min after cuff deflation.

RESULTS

Significant differences were found in the average carotid IMT value between subjects with delivered dialysis dose (Kt/V) > or =1.2 and <1.2 (0.89 +/- 0.21 vs 1.04 +/- 0.11, P = 0.0045). A correlation between Kt/V and IMT (r = 0.366, P = 0.004) was demonstrated. FMD values of the brachial artery did not correlate with Kt/V. A correlation between low molecular weight heparin per kg of body mass and maximal percent of FMD was demonstrated (r = -0.242, P = 0.049). The maximal percent of brachial FMD was correlated with absolute difference between pre- and postdialysis pulse pressure values (r = -0.265, P = 0.033). In a partial correlation with haemoglobin as control, a variable significant correlation between total erythropoietin dose and maximal carotid IMT (r = -0.262, P = 0.036) was found. In a multiple linear regression model, Kt/V was independently correlated with carotid IMT values (beta = -0.227, P = 0.0335).

CONCLUSION

This study has demonstrated the association between HD procedure and early atherosclerosis markers. HD treatment has to be considered as potential modifying factor in atherosclerosis development.

Diurnal variation of blood pressure; reproducibility and association with left ventricular hypertrophy in hemodialysis patients

OBJECTIVE

The objective of this paper is to describe the pattern of diurnal blood pressure (BP) change in hemodialysis patients, determine the association of the non-dipping pattern of diurnal BP with left ventricular mass index (LVMI), and to determine if the nocturnal profile of BP is reproducible when repeated over time.

METHODS

In a cross-sectional study, ambulatory blood pressure monitoring (ABPM) was performed over a midweek 44-h period and echocardiography was performed on the interdialytic day. Patients with a night/day systolic and diastolic BP ratio on both days >0.9 were defined as non-dippers. Ambulatory blood pressure monitoring was repeated at 6 and 12 months follow-up.

RESULTS

Of the 59 patients, 88% were African-American, and 48% were non-dippers. Mean LVMI was significantly higher in the non-dipper (68.3+/-25 g/height) compared to the dipper patients (55.6+/-16, P<0.05). Mean nocturnal systolic BP (r=0.35) and the night/day systolic BP ratio (r=0.39) had a higher correlation with M-mode LVMI than pre-dialysis (r=0.32). After adjustment for 44-h mean SBP, night/day systolic BP ratio remained independently associated with LVMI (beta coefficient 147.62, P=0.004). Of 12 patients who had a non-dipper profile at baseline, 11 (92%) demonstrated the same profile after 6 months and 1 year of follow-up.

CONCLUSION

Many hemodialysis patients demonstrate a non-dipper profile; the degree of decline in nocturnal BP is independently associated with LVMI even after adjustment for mean BP. Patients who are identified as non-dippers consistently reproduce the same profile over time.

Blood pressure measurement in hemodialysis patients

Measurement of blood pressure (BP) poses some unique challenges in hemodialysis patients. Timing of BP measurement in relation to dialysis, changes in interdialytic weight gain, and inconsistent BP measurement technique in dialysis units contribute to the variability of BP readings in this population. This may contribute to the equivocal relationship between hypertension and cardiovascular outcomes documented in several epidemiologic studies in this population. Home BP readings are promising, but need to be validated as a measure of the burden of hypertension in this population. It is important to standardize BP measurement in all hemodialysis units according to published guidelines to improve the management of hypertension. Future research studies should carefully validate the technique used to measure BP.

Effects of an angiotensin II receptor blocker, valsartan, on residual renal function in patients on CAPD

BACKGROUND

Both residual renal function and blood pressure (BP) control contribute to patient survival in patients receiving continuous ambulatory peritoneal dialysis (CAPD). It is unknown whether antihypertensive drugs affect residual renal function in addition to BP reduction.

METHODS

We examined the effects of an angiotensin II receptor blocker, valsartan, on residual renal function and total clearance (renal and peritoneal) in 34 Japanese CAPD patients from 3 months to 2 years after the start of dialysis therapy. Patients were randomly assigned to valsartan (n = 18; age, 63.5 +/- 3.7 years; 11 men, 7 women) or a control group (n = 16; age, 63.5 +/- 3.3 years; 10 men, 6 women). Conventional antihypertensive treatment was continued in all patients to achieve the target BP in both groups of 130/80 mm Hg or less, measured at home.

RESULTS

BP reduction was similar in the valsartan and control groups. Valsartan significantly slowed the progressive decline in both residual renal function (3.2 +/- 0.3 to 4.3 +/- 0.7 mL/min/1.73 m2) and total clearance (42.1 +/- 3.2 to 48.3 +/- 4.8 L/wk/1.73 m2) by dialysis in CAPD patients compared with controls (5.9 +/- 0.5 to 2.8 +/- 0.4 mL/min/1.73 m2; 47.1 +/- 4.8 to 31.4 +/- 5.2 L/wk/1.73 m2).

CONCLUSION

This study shows that in patients with hypertension starting CAPD therapy, valsartan slows the decline in residual renal function and contributes to maintenance of weekly creatinine clearance and Kt/V (fraction per dialysis), which are the major factors contributing to the mortality and morbidity of CAPD patients. This effect appears to be mostly a result of maintaining residual renal function.

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.

Calcium-channel blockers and end-stage renal disease: pharmacokinetic and pharmacodynamic considerations

PURPOSE OF REVIEW

To characterize the pharmacokinetics and pharmacodynamics of the different calcium-channel blockers.

RECENT FINDINGS

Calcium-channel blockers have been in use for some time in the end-stage renal disease population. Their primary use has been as antihypertensive and antianginal therapies. In this regard, they are effective agents. Recently, it has been noted that dialysis-related hypotension occurs less frequently in calcium-channel blocker treated patients. Also, access patency and overall patient survival are improved with calcium-channel blocker therapy.

SUMMARY

Calcium-channel blockers are useful agents for the control of hypertension in end-stage renal disease patients and appear to favorably influence survival in this population. Calcium-channel blockers are not dialyzable and their pharmacokinetics do not substantially change with renal failure therefore they do not require dose adjustment based on level of renal function. Too few studies exist to determine if individual calcium-channel blockers differ in their effects. Prospective, randomized, controlled clinical trials are needed in the end-stage renal disease population to better understand the role of calcium-channel blockers in the excess cardiovascular disease burden of this population.

A comparison of standardized versus "usual" blood pressure measurements in hemodialysis patients

Hypertension is very common and contributes to the high cardiovascular morbidity in patients undergoing chronic hemodialysis therapy. However, the accuracy of blood pressure measurement in this population has not been well studied. We conducted a cross-sectional study of 270 patients at seven outpatient hemodialysis units. Predialysis and postdialysis seated blood pressure readings obtained by the dialysis unit using automated blood pressure monitors were significantly higher than readings obtained by a research nurse following standard procedures for blood pressure measurement (14.3/7 mm Hg higher predialysis; P < 0.01; 13.6/4.4 mm Hg higher postdialysis; P < 0.05). In 55% of patients, the postdialysis systolic blood pressure measured in the dialysis unit was at least 10 mm Hg higher than the standard reading. Bland-Altman analyses indicated poor agreement between the two readings. This study shows a marked discrepancy between routine dialysis unit and standardized blood pressure measurements. Blood pressure is frequently overestimated by routine dialysis unit readings. In light of these findings, efforts should be made to standardize blood pressure readings in hemodialysis units based on American Heart Association recommendations for blood pressure measurement.