Blood Pressure In Hemodialysis Patients Research Articles

The development of concepts of volume control

SUMMARY: The history of hemodialysis includes some aspects concerning specifically the extracellular volume and blood pressure control issue. the goal of this historical paper is to review what appears today as the main steps in the analysis of blood pressure normalization using the extracellular volume (and sodium content of the body) control. Clinical observations have more often preceded the formal expression of concepts. the ‘dry weight’ concept was formulated seven years after the first maintenance dialysis patient's malignant hypertension was cured by a combination of low salt diet and strong ultrafiltration leading to a decreased extracellular volume. Fifteen years later, the development of shortened hemodialysis sessions—with restricted possibilities of volume control—has led to a resurgence of hypertension in dialysis patients. This late increasing prevalence of hypertension was reported in the literature only several years after shortened dialysis had become almost universal. Some concepts not yet formalized, such as the ‘lag time’between volume and blood pressure variation in dialysis may be needed to analyze and understand what may presently appear as a failure of volume control of blood pressure in hemodialysis patients.

Seasonal variation of blood pressure in maintenance hemodialysis.

Seasonal variation in arterial blood pressure has been reported in studies with hypertensive and normotensive subjects. However, the influence of seasonal change on blood pressure of hemodialysis patients has not been reported. To investigate the seasonal variation of blood pressure in Brazil, a tropical country, in patients on hemodialysis. Prospective, cohort study. Dialysis unit of a tertiary medical center (a teaching hospital of the University of São Paulo School of Medicine, São Paulo). Sixteen patients with chronic renal failure undergoing hemodialysis. Blood pressure, body weight, and ambient temperature were evaluated during 6 hemodialysis sessions carried out on 13 days during the four seasons. The diastolic blood pressure was lower in summer than in fall and winter (95 +/- 8 vs 107 +/- 10 and 101 +/- 10 mmHg, respectively; p < 0.05). The same was observed with mean blood pressure (116 +/- 8 vs 130 +/- 11 and 124 +/- 9 mmHg, respectively; p < 0.01). On the other hand, the ambient temperature was higher in summer than in fall and winter (23.0 +/- 1.6 vs 19.5 +/- 3.0 and 15.8 +/- 1.9 degrees C, respectively; p < 0.01). We concluded that for patients with chronic renal failure the blood pressure has a seasonal variation with higher pressures in fall and winter than in summer. Thus, further studies are needed to elucidate the impact of this observation on the adjustment of antihypertensive treatment and on morbidity and mortality in maintenance dialysis patients.

M007 The effect of interdialytic weight gain on blood pressure in hemodialysis patients

M007 The effect of interdialytic weight gain on blood pressure in hemodialysis patients

Interdialytic weight gain and 48-h blood pressure in haemodialysis patients

Hypertension, which is often associated with hypervolaemia, is common in haemodialysis patients and is a known determinant of target organ damage. Interdialytic weight gain due to volume overload has also been associated with mortality in haemodialysis patients. We therefore studied 27 chronic haemodialysis patients who underwent 48-h ambulatory blood pressure monitoring between two midweek dialysis sessions, and 2D and M-mode echocardiography for determination of left ventricular mass index. Left ventricular hypertrophy (left ventricular mass index in men > 131 g/m2, women > 100 g/m2) was present in 70% (19/27) patients despite a mean 48-h blood pressure of 132 +/- 19/81 +/- 15 mmHg. Mean interdialytic weight gain was 1.6 +/- 0.8 kg and was not related to left ventricular mass index. Two patterns of interdialytic blood pressure change were apparent: in group 1 (16 patients) 48-h blood pressure increased (+19 +/- 12/13 +/- 9 mmHg), whereas in group 2 (11 patients) blood pressure fell (-10 +/- 13/-8 +/- 10 mmHg P < 0.0001). In both groups the number of hypertensive patients (group 1, 10/16; group 2, 6/11), the 48-h blood pressure (132 +/- 20/80 +/- 15 vs 132 +/- 18/82 +/- 15 mmHg) and interdialytic weight gain (+1.9 +/- 0.7 vs +1.3 +/- 0.7 kg) were similar. There was also no correlation between interdialytic blood pressure change and weight gain in either group. We conclude that interdialytic blood pressure changes cannot be directly related to interdialytic fluid gain, even in apparent volume-dependent hypertension, emphasizing the importance of additional factors in the control of blood pressure in end-stage renal disease.

Impact of nitric oxide on blood pressure in hemodialysis patients

Nitric oxide (NO) is a powerful vasoactive agent that contributes to the regulation of blood pressure (BP). However, the role of NO in uremic patients and during the course of hemodialysis is still debated. Blood L-arginine concentrations and exhaled NO concentrations were measured in 22 healthy controls and in 22 hemodialysis patients before and after dialysis. On the basis of their BP response during hemodialysis, the patients were divided into three groups: 6 of the 22 patients presented with a decrease in BP during dialysis (group 1), eight presented with a stable BP (group 2), and eight with an increase in BP (group 3). The exhaled NO concentration was higher in dialysis patients than in healthy controls (22.7 ± 2.6 ppb in dialysis patients v 16.7 ± 0.9 ppb in controls, mean ± SEM, P ± 0.044). The predialysis and postdialysis exhaled NO concentrations were inversely correlated with the change in BP during hemodialysis ( r = -0.47, P = 0.013). Patients with a decrease in BP (group 1) had the highest NO concentrations; patients with an increase in BP (group 3) had the lowest values; and patients with a stable BP during the course of dialysis (group 2) had intermediary values (trend test, P = 0.0291). In addition, both the exhaled NO concentration and the blood L-arginine concentration decreased during dialysis in all patients ( P = 0.005 and P = 0.001, respectively). These results provide several novel insights into NO metabolism and BP regulation during hemodialysis: (1) maintenance hemodialysis is associated with a chronic increase in NO concentrations; (2) changes in BP during hemodialysis are inversely correlated with exhaled NO concentrations, higher NO levels being associated with a decrease in BP and lower NO levels with an increase in BP during dialysis; (3) blood L-arginine levels decrease during hemodialysis, and this reduction may in turn influence NO production.

Ambulatory blood pressure monitoring in dialysis patients and estimation of mean interdialytic blood pressure

To define blood pressure (BP) patterns and control in dialysis patients, 48-hour ambulatory BP monitoring was performed in 36 hemodialysis and 18 peritoneal dialysis patients. Monitoring began during a dialysis session for hemodialysis patients. Data revealed significantly lower diastolic BP (DBP) and lower diastolic load (percentage of diastolic values > 90 mm Hg) in hemodialysis patients compared with peritoneal dialysis patients (80.6 mm Hg v 88.8 mm Hg, respectively, [P < 0.03] and 26% v 45%, respectively [P < 0.03]) for the 48-hour period. When the 2 days were analyzed separately, the difference in diastolic pressures and loads was significant only for the first (dialysis) day. Similarly, trends toward lower systolic BP (SBP) and systolic load in hemodialysis patients existed throughout monitoring and were greater in magnitude during the first day. BP data were fit to a random-coefficient growth curve model to detect periodicity. This sensitive model did not detect diurnal variation of BP in either group. The incidence of hypotension did not differ between the two groups (2.0% v 1.0% of total observations, hemodialysis v peritoneal dialysis). In the hemodialysis group, the proportion of hypotensive observations was significantly greater during the 4 hours postdialysis compared with other periods (5.6% v 1.6%; P < 0.02), a finding that likely reflects the practice of holding antihypertensives until after hemodialysis. However, patient diaries did not reflect hypotensive symptoms during this time. In the hemodialysis group, mean BP and predialysis BP did not correlate with interdialytic sodium load or weight gain. Predialysis and postdialysis BP (recorded by dialysis nurses) correlated significantly with mean BP. Predialysis SBP overestimated mean SBP by an average of 10 mm Hg, while postdialysis SBP underestimated mean SBP by an average of 7 mm Hg. To create formulas to estimate mean SBP and DBP in hemodialysis patients, multiple linear regression was used to model these variables against age, sex, race, and average prehemodialysis/posthemodialysis BP. The model achieved a high degree of fit (r2 = 0.72 for SBP; r2 = 0.65 for DBP), demonstrating that prehemodialysis and posthemodialysis BP can be used to predict mean BP in hemodialysis patients. In summary, our data show the absence of a diurnal variation of BP in dialysis patients and lower BP in hemodialysis patients compared with peritoneal dialysis patients. Among hemodialysis patients, more hypotension occurred after dialysis compared with other periods, and predialysis and postdialysis BP can be used to model mean BP levels.

Relationship between blood pressure during haemodialysis and ambulatory blood pressure in between dialyses

Ambulatory blood pressure measurements in haemodialysis patients are relevant in view of the high cardiovascular morbidity and mortality in chronic haemodialysis patients. Twelve normotensive patients were studied from the beginning of one dialysis until the end of the next (mean 64 h, SD 19 h) using a Spacelabs oscillometric blood-pressure recorder. A circadian blood pressure rhythm was present in six of the 12 patients. In seven patients the lowest pressure recorded (including the dialysis sessions) occurred 5-6 h after dialysis (late post-dialysis dip). Blood pressure did not increase sharply in the hours before dialysis although it increased slightly in the interdialytic interval as a whole, at a mean rate of 5.6 mmHg per 24 h (SD 4.1, P < 0.001). We could not find a blood pressure measurement during dialysis (or combination of measurements) which reliably reflects interdialytic blood pressure: the 95% confidence intervals were 25 mmHg or higher. Ambulatory blood pressure measurements are needed for adequate monitoring of the control of blood pressure in haemodialysis patients.

Keynote Lecture: Erythropoietin and systemic hypertension

Systemic hypertension has been reported to develop, or to worsen, in 20–30% of patients treated with recombinant human erythropoietin (r-HuEPO) worldwide. The greatest increases in blood pressure affect day-time systolic and night-time diastolic blood pressure. Hypertension may develop in some patients as early as 2 weeks and in others as late as 4 months after the start of r-HuEPO treatment. In haemodialysis patients with systemic hypotension, r-HuEPO usually induces a 10% increase in blood pressure, with no significant change in the frequency of hypotensive episodes. Several risk factors for the development, or worsening, of hypertension after r-HuEPO therapy have been identified. They include the presence of pre-existing hypertension, rapid increase in haematocrit, a low baseline haematocrit before r-HuEPO administration, high doses and i.v. route of administration, the presence of native kidneys, a genetic predisposition to hypertension, and possibly a younger age. There are several potential mechanisms by which r-HuEPO therapy may increase blood pressure in haemodialysis patients. They include increased blood viscosity; the loss of hypoxic vasodilation; the activation of neurohumoral systems (catecholamines, the rennin-angiotensin system); and especially a direct vascular effect. This last mechanism is supported by several data, and many factors may be involved in its pathogenesis (an increased cell calcium uptake; an imbalance in local vasoactive agents, with increased synthesis of ET-1; a mitogenic effect; and a platelet-dependent mechanism).

Influence of interdialytic weight gain on blood pressure in hemodialysis patients.

The role of fluid overload in the pathogenesis of hypertension in hemodialysis patients is not clear. One problem is the lack of techniques to determine the fluid state. Recent new noninvasive techniques have become available which make it possible to accurately determine the dry weight in these patients. Therefore, we studied the influence of interdialytic weight gain on interdialytic blood pressure in 10 normotensive and 10 hypertensive hemodialysis patients without antihypertensive medication. The dry weight was determined with echography of the vena cava. The blood pressure was measured during 2-day and 3-day interdialytic periods using Spacelabs 90207 ambulatory blood pressure monitors. Mean systolic and diastolic blood pressures of the last day of the interdialytic period were compared with mean systolic and diastolic blood pressures of the 1st day of the interdialytic period. Although the interdialytic weight gain in the normotensive and hypertensive patients was greater during the 3-day than during the 2-day interdialytic period, the interdialytic systolic and diastolic blood pressure changes were not greater during the 3-day period. Also, the interdialytic blood pressure rise did not correlate significantly with weight gain, neither in the normotensive nor in hypertensive patients. No significant interdialytic blood pressure changes were found between the normotensive and the hypertensive patients. We conclude that fluid overload does not seem to play a major role in interdialytic blood pressure control in normotensive and hypertensive hemodialysis patients.

Long-Term Oral Calcium Supplementation Reduces Diastolic Blood Pressure in End Stage Renal Disease. A Randomized, Double-Blind, Placebo Controlled Study

Previous studies suggest that oral calcium supply reduces blood pressure in patients with mild to moderate hypertension. The aim of this study was to determine whether oral calcium supply reduces blood pressure in patients undergoing haemodialysis. The study was randomized, double-blind, and placebo controlled. Eleven patients received two grams of calcium per day and 12 patients received placebo. Three patients (one from the calcium group and two from the placebo group) dropped out within the first month. The groups were comparable at inclusion regarding blood pressure, weight, and serum values. Blood pressure measurements were auscultatory with a mercury manometer and diastolic blood pressure was measured as Korotkoff phase V. At inclusion a significant positive correlation between serum phosphate and blood pressure was found. After a study period of six months a significant reduction in diastolic blood pressure was found between the two groups (p < 0.05), but no difference was found in systolic blood pressure. The reduction in diastolic blood pressure was 6.9 mmHg of the pretreatment level in the calcium group. In conclusion, the treatment of secondary hyperparathyroidism with oral calcium gives good benefits in the regulation of diastolic blood pressure. A well controlled phosphate homeostasis may also be of importance for the control of blood pressure in haemodialysis patients.

Effect of Continuous Ambulatory Peritoneal Dialysis on Blood Pressure Control

To assess the efficacy of blood pressure control in continuous ambulatory peritoneal dialysis (CAPD), blood pressure was examined sequentially in 63 CAPD patients transferred from hemodialysis (HD), and in 97 patients started de novo on CAPD (NEW), over periods ranging from 3 to 63 months. Blood pressure changes were related to changes in body weight, hematocrit, and treatment with recombinant human erythropoietin (rHu-EPO), as well as to changes in antihypertensive drug requirements. Both groups of patients showed an immediate improvement in blood pressure control at 1 month, as manifested by an absolute decrease in blood pressure in HD patients (-4.3% +/- 2.1% [SEM], P < 0.05) and by a decrease in antihypertensive drug requirements in NEW patients (from 78% to 43.3%). This early improvement in blood pressure appeared to be volume-related, as reflected by changes in body weight. Both groups showed an additional decrement in blood pressure at approximately 6 months (-7.8% +/- 2.6% [SEM], P < 0.05, HD group; -3.4% +/- 2.4% [SEM], P < 0.05, NEW group). Treatment of anemia with rHu-EPO in 22 of the CAPD patients had no effect on blood pressure. CAPD thus appears to be more effective than HD in controlling blood pressure.

Parathyroidectomy and Blood Pressure in Hemodialysis Patients

To assess whether parathyroidectomy (PTx) affects blood pressure (BP) in hemodialysis (HD) patients, we studied 11 uremics on HD treatment for 8.2 +/- 0.9 years who underwent successful PTx. As the control group, we selected 11 HD patients not submitted to PTx, matched with the study group for sex, age, years on HD, dialysis procedure and BP values. In the controls, BP and body weight did not change during the 2 years of observation. In the patients, BP remained stable in the year before PTx. PTx caused a progressive reduction in BP in 7 of the 11 patients. The fall was significant from the 3rd quarter onward (mean BP values before PTx: 139/82 mm Hg, 1 year after PTx: 122/75 mm Hg). The magnitude of the hypotensive effect of PTx was related to the pre-PTx systolic BP value (r = -0.70, p = 0.016). PTx also caused a significant progressive increase in body weight (1.56 +/- 0.57 kg 1 year after PTx). In conclusion, PTx causes BP fall in HD patients regardless of whether their preintervention values are normal or increased. The BP reduction occurs in concomitance with a consistent increase in body weight. BP variations are clinically relevant and may be related to the post-PTx calcium efflux from the vessel wall.

Blood pressure in hemodialysis patients during amelioration of anemia with erythropoietin.

This study analyzed blood pressure in hemodialysis patients treated with epoetin beta in multicenter trials. Antihypertensive drugs were prescribed as usual. Placebo-controlled trials compared epoetin (100 to 150 U/kg; N = 151) with placebo (N = 78) for 82 days. Hemoglobin (108 +/- 18 versus 75 +/- 14 g/L) (mean +/- SD) and diastolic blood pressure (84 +/- 14 versus 78 +/- 15 mm Hg) were greater (P less than 0.05) after epoetin. Clinically important increases in blood pressure (increases in diastolic blood pressure greater than or equal to 10 mm Hg and/or drug therapy) were more frequent with epoetin (58 versus 37%; P = 0.005). A dose-response trial compared epoetin, 25 U/kg (N = 42), 100 U/kg (N = 40), and 200 U/kg (N = 39) for 138 days. Increases in hemoglobin were dose dependent, but clinically important increases in blood pressure were not. In analyses of all patients treated with epoetin (N = 272), no baseline or final level of hemoglobin, or rate of hemoglobin rise, was a threshold for a rise in blood pressure. Patients requiring antihypertensive drugs or having uncontrolled hypertension (diastolic blood pressure greater than 90 mm Hg) at baseline had decreases in blood pressure (P less than 0.05) with antihypertensive therapy. Thus, compared with placebo, 21% of patients had clinically important increases in blood pressure during amelioration of anemia. The baseline or final levels of hemoglobin, the extent or rate of hemoglobin rise, or uncontrolled hypertension or antihypertensive drug use at baseline were not confirmed as risks. Antihypertensive drug therapy was important for blood pressure control.

Body Fluid Spaces and Blood Pressure in Hemodialysis Patients During Amelioration of Anemia With Erythropoietin

Blood pressure (BP) may increase in hemodialysis patients during treatment of anemia with recombinant human erythropoietin (r-HuEPO). Since fluid volume is a determinant of BP in dialysis patients, changes in body fluid spaces during r-HuEPO therapy could affect BP. Thus, 51Cr-labeled red blood cell (RBC) volume, inulin extracellular fluid (ECF) volume, and urea total body water (TBW), as well as cardiac output, plasma renin activity (PRA), and plasma aldosterone concentration were determined postdialysis before and after r-HuEPO therapy in patients in whom changes in BP could be managed by ultrafiltration alone. Eleven patients entered the study: one had a renal transplant and two required addition of antihypertensive drug therapy and were excluded; eight, of whom two required antihypertensive drug therapy following the study, were included in the analyses. Results revealed an increase in predialysis hemoglobin from 67 to 113 g/L (6.7 to 11.3 g/dL) (P = 0.001) during 18 +/- 6 weeks of therapy. Predialysis diastolic BP increased from 80 to 85 mm Hg (P = 0.07), while postdialysis diastolic BP was unchanged at 73 mm Hg. 51Cr-RBC volume increased, from 0.7 to 1.3 L (P = 0.004). ECF tended to decrease, from 13.7 to 10.8 L (P = 0.064), while TBW decreased to a similar extent, but not significantly, 34.3 to 31.2 L (P = 0.16). Postdialysis ECF volume was positively correlated with mean arterial BP at baseline (r = 0.89, P = 0.007) and after therapy (r = 0.74, P = 0.035). However, the regression lines for this relationship were different (P = 0.022) before and after therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Is Calcitonin Gene-related Peptide (CGRP) a Regulator of Blood Pressure in Hemodialysis Patients?

Is Calcitonin Gene-related Peptide (CGRP) a Regulator of Blood Pressure in Hemodialysis Patients?

Neuropeptide Y and Blood Pressure in Haemodialysis Patients.

To investigate the relationship between plasma neuropeptide Y (NPY) concentrations and blood pressure in haemodialysis (HD), we measured plasma immunoreactive neuropeptide Y (IR-NPY) concentrations and blood pressure before and after HD in 71 patients undergoing maintenance HD. Plasma IR-NPY concentrations were measured by radioimmunoassay after extraction with Sep-Pak C18 cartridges. We corrected the plasma IR-NPY values after HD by reference to the ratio of the plasma total protein levels before HD to the levels after HD, in order to exclude the influence of the haemoconcentration caused by HD. Plasma IR-NPY concentrations before and after HD in 71 patients undergoing maintenance HD were 413 +/- 94 pg/ml and 340 +/- 90 pg/ml (mean +/- SD), respectively. Plasma IR-NPY concentrations before HD in 28 hypertensive patients with HD (398 +/- 91 pg/ml) were not significantly different from those in 40 normotensive (427 +/- 98 pg/ml) and 3 hypotensive (372 +/- 21 pg/ml) patients with HD (P greater than 0.1). Plasma IR-NPY concentrations after HD in 9 patients whose systolic blood pressure fell more than 30 mmHg during HD (409 +/- 52 pg/ml) were significantly higher than those in the other patients (P less than 0.025). These findings suggest that the release of NPY is increased when the blood pressure falls during HD in patients undergoing maintenance HD.

Effect of a Calcium Infusion on the Vascular Stability during Hemodialysis

In order to test the hypothesis that higher, serum calcium levels in hemofiltration (HF) patients, as compared to hemodialysis (HD) patients, might be a contributing factor for the better vascular stability during HF, a calcium infusion was given during HD. Serum calcium concentrations, plasma catecholamines, blood pressure, and clinical incidents were monitored leading to the following results: (1) An increase in the arterial serum calcium concentration from 4.04 ± 0.52 to 5.74 ± 0.42 mEq/1 did not generally raise the plasma catecholamines and the blood pressure in HD patients. (2) In spite of a slight reduction of hypotensive episodes during HD with calcium infusion leading to higher levels of calcium than in HF, the incidence of hypotension was still less frequent during HF. (3) Therefore it seems unlikely that the higher calcium level during HF plays a very important role with regard to improved vascular stability.