Control In Hemodialysis Patients Research Articles

Calf Bioimpedance Ratio Improves Dry Weight Assessment and Blood Pressure Control in Hemodialysis Patients

Background: Chronic fluid overload due to overestimation of dry weight (DW) is the major factor in the development of hypertension in hemodialysis (HD) patients. The present study was undertaken to investigate whether bioimpedance ratio in the calf (Calf-BR = impedance at 200 kHz/impedance at 5 kHz) could be a useful hydration marker for estimation of DW and facilitate better control of blood pressure (BP) in HD patients. Methods: Target range of Calf-BR was derived from 157 healthy Chinese subjects. Post-dialysis Calf-BR was measured in 117 stable, non-edematous HD patients. Those with Calf-BR(s) above target level had their DW(s) gradually reduced under the guidance of Calf-BR. Results: The Calf-BR was normally distributed and increased with age, but was independent of BMI and gender in both healthy subjects and dialysis patients. HD patients with Calf-BR above age-stratified target range had significantly higher home BP, in spite of more antihypertensive treatments (p = 0.058). The patients who reached the target range of Calf-BR by decreasing DW, had their home BP significantly decreased, along with reduction in antihypertensive medications (p = 0.012). Conclusion: Recognition and correction of chronic fluid overload based on age-stratified Calf-BR is helpful in hypertension control in Chinese HD patients.

Intracorporeal Glucose Disposal During Hemodialysis After a Standardized Glucose Load

The aim of this study was to quantify intracorporeal clearance and disposal of glucose after the administration of a standardized glucose load during regular hemodialysis done in stable and non-diabetic patients and to account for effects of extracorporeal clearance. A standardized load of glucose was administered approximately 30 min after starting hemodialysis with a constant dialysate glucose of 5.0 +/- 0.2 mmol/L. Glucose in the arterial line blood and in dialysate outflow was measured at baseline and in short intervals for a period of 1 h after the infusion. Tests were repeated within 1 week. Nine patients completed the study. Extracorporeal blood and dialysate flows were 304 +/- 34 and 500 mL/min, respectively. The intracorporeal clearance of glucose was 327 +/- 137 mL/min and 69.1 +/- 9.4% of total glucose clearance. Mass balance assessed from dialysate samples showed that 60.1 +/- 10.5% of glucose injected was disposed intracorporeally. The fraction of intracorporeal clearance and the fraction of intracorporeal glucose disposal were highly correlated (r = 0.94, p < 0.0001). The fraction of glucose disposed in hemodialysis patients can be determined from the amount of glucose injected and from the amount of glucose removed extracorporeally during hemodialysis without blood sampling. This measure could be of interest in surveillance of glucose control in hemodialysis patients.

Development and utility of a multi‐dimensional grid to assess individual mineral metabolism control in hemodialysis patients: A potential aid for therapeutic decision making?

A grid was developed to evaluate control of serum calcium, phosphate, and parathyroid hormone levels in hemodialysis patients, based on guideline recommendations (National Kidney Foundation Kidney Disease Outcomes Quality Initiative and Canadian Society of Nephrology), and its face validity was examined in a representative sample of Canadian patients. A retrospective chart review was undertaken in hemodialysis patients from 7 Canadian units. Patients >18 years, on hemodialysis for > or =12 months, and > or =3 parathyroid hormone levels measured > or =1 month apart were included. The grid classified mineral metabolism control as optimal, suboptimal, or poor (mean of 3 measurements). Medication use, hospitalization, and Emergency Department visits were evaluated in relation to grid occupancy. A second comparative analysis of grid occupancy was undertaken on prevalent hemodialysis cases in British Columbia in 2008. Data from 268 patients (mean age 62.3 years) were analyzed. Using National Kidney Foundation Kidney Disease Outcomes Quality Initiative guidelines, 17.5%, 28.8%, and 53.7% of patients had optimal, suboptimal, and poor control, respectively, of all 3 parameters (calcium, phosphate, and parathyroid hormone). Using Canadian Society of Nephrology criteria, optimal, suboptimal, and poor control rates were 6.3%, 4.2%, and 89.5%, respectively. Poor control was a possible or a probable cause of hospitalization or Emergency Department attendance in 8 patients. Data from British Columbia in 2008 (n=1858) show optimal, suboptimal, and poor control rates of 15.8%, 24.5%, and 59.7%, respectively. Poor mineral metabolism control among Canadian hemodialysis patients is not showing improvement. The therapeutic grid is a valid tool and may help guide therapeutic decisions, quality control initiatives, and patient counseling. http://www.ukidney.com/bone-and-mineral-metabolism-resource.

Association of glycated albumin, but not glycated hemoglobin, with calcaneus quantitative ultrasound in male hemodialysis patients with type 2 diabetes mellitus

Sustained high glucose impairs bone metabolism in patients with type 2 diabetes mellitus (T2DM). In this study, the relationship between glycemic control and bone metabolism was examined in male hemodialysis (HD) patients with T2DM. To avoid the effect of menstruation and the menstrual cycle, obesity, and glycosuria-induced hypercalciuria on bone metabolism, male anuric nonobese HD patients with T2DM (n = 42) were enrolled. Calcaneus stiffness index (SI) was determined using ultrasound after HD session. Casual plasma glucose (PG), glycated hemoglobin (HbA 1c), and glycated albumin (GA) were measured before the HD session. In simple regression analysis, log PG ( r = −0.333, P < .05) and log GA ( r = −0.350, P < .05), but not log HbA 1c ( r = −0.134, P = .3985), exhibited significant and negative correlations with calcaneus SI. In multiple regression analysis including log BMI, log cCa × Pi product, and log PG, log PG was associated significantly in a negative manner with calcaneus SI, in addition to log cCa × Pi product. When log PG was replaced with log GA or log HbA 1c, log GA, but not log HbA 1c, emerged as a significant factor associated. The mechanism as to why HbA 1c failed to associate could be explained by its false reduction by erythropoietin injection. The present study supported the notion of GA as an appropriate indicator for glycemic control in HD patients with T2DM. Furthermore, it is suggested that poor glycemic control might be a significant factor toward decreasing calcaneus SI in T2DM HD patients.

Poor Glycemic Control is a Significant Predictor of Cardiovascular Events in Chronic Hemodialysis Patients With Diabetes

We investigated the impact of glycemic control on the emergence of cardiovascular disease (CVD) in diabetic patients who were on maintenance hemodialysis in a prospective observational study. One hundred and thirty-four diabetic hemodialysis patients (63 +/- 10 years-old, hemodialysis duration of 4.5 +/- 3.9 years) at a single dialysis center were enrolled. The cohort was observed prospectively for 5 years, and the emergence of fatal and non-fatal CVD was recorded. Patients were categorized into two groups; good (mean hemoglobin (Hb) A1C <7.0%, N = 65) and poor HbA1C (mean HbA1C > or = 7.0%, N = 69). The relationship between glycemic control and CVD emergence was evaluated by Kaplan-Meier estimation and Cox proportional hazard models. During the follow-up period, 50 CVD events were observed. The cumulative CVD incidence in the poor HbA1C group was significantly higher than that of the good HbA1C group, as determined by Kaplan-Meier estimation (P = 0.0250, log-rank test). After adjustment for gender, age, duration of dialysis, and past history of CVD, a multivariate Cox proportional hazard model showed that poor HbA1C was a significant predictor of CVD events (hazards ratio [HR] 1.828 [95% CI, 1.008-3.314], P = 0.0470). When ischemic heart disease, cerebral infarction, and arteriosclerosis obliterans were determined as an endpoint, both HbA1C levels and the poor HbA1C group were significant predictors for the emergence of CVD (HR 1.269 per 1% HbA1C [95%CI, 1.022-1.574], P = 0.0307,and HR 2.816 [95% CI, 1.377-5.759], P = 0.0046, respectively). In diabetic hemodialysis patients, poor glycemic control is a significant, independent predictor of the emergence of CVD, indicating the importance of careful management of glycemic control in hemodialysis patients.

Behavioral Modeling to Guide Adherence to Fluid Control in Hemodialysis Patients

This study used the health belief model (HBM) and the transtheoretical model (TTM) to assess hemodialysis (HD) patients' readiness to comply with recommended fluid intake as it relates to their perceptions of therapy and disease. This was a multicenter, cross-sectional study. The setting involved 3 hospital-based HD centers in Lebanon. Patients included 172 consenting HD patients who had been on HD for at least 3 months and were mentally stable. Placement of patients into TTM stages was based on their readiness to comply with recommended fluid intake, as confirmed by 4-week interdialytic weight-gain measures, and taking into account their perceptions toward therapy (using HBM constructs). Mean scores of HBM constructs for each patient were placed in one of the TTM stages of readiness to change. This study included 54.1% males, the average age was 57.8 +/- 14.0 (SD) years, and average number of years on dialysis was 4.6 +/- 4.9. Regarding stages, 18.5% of participants were placed in precontemplation, 40.0% in contemplation, 38.1% in preparation, and 3.4% were in the action/maintenance stages. The HBM constructs were significantly associated with TTM (P < .01). Perceptions of benefits (P = .04) and self-efficacy (P < .01) were significantly associated with TTM. Compliance is a multifaceted topic, essential for the survival and quality of life of HD patients. A better understanding of patients' beliefs and level of self-efficacy is a fundamental key to enhancing patients' compliance to therapy and achieving the required behavioral modifications.

Glycated hemoglobin or glycated albumin for assessment of glycemic control in hemodialysis patients with diabetes?

This commentary discusses the findings of a study by Peacock et al., who measured levels of glycated hemoglobin (HbA(1c)) and glycated albumin in patients with diabetes who either were or were not on hemodialysis in an effort to determine which marker is the better indicator of glycemic control. They found that HbA(1c) and glycated albumin levels are both independently associated with serum glucose level. However, HbA(1c) level--unlike glycated albumin level--was also influenced by hemodialysis, hemoglobin level, and erythropoietin dose. Although we agree that glycated albumin level could be a better indicator of glycemic control than HbA(1c) level in patients on hemodialysis who have diabetes and anuria, this conclusion might not be applicable to patients with massive proteinuria or to those on peritoneal dialysis. Further studies are required to confirm the target glycated albumin level that is necessary to ensure a good prognosis for patients with diabetes who are on hemodialysis because no clear consensus has yet been reached. In addition, more data are needed to determine at which stage of kidney disease measurement of glycated albumin levels becomes preferable to assessment of HbA(1c) level.

Glycated albumin as an improved indicator of glycemic control in hemodialysis patients with type 2 diabetes based on fasting plasma glucose and oral glucose tolerance test

Aims To compare glycated albumin (GA) with glycated hemoglobin (HbA1c) as an indicator of glycemic control in hemodialysis patients with diabetes mellitus (DM), based on relationships with plasma glucose (PG) after overnight fasting and during 75 g oral glucose tolerance test (OGTT). Methods GA, HbA1c, plasma glucose during 75 g OGTT, and serum pentosidine were determined in DM hemodialysis patients ( n = 23, male/female 9/14). Results Significant positive correlations were found for GA and HbA1c with fasting PG (GA, r = .660, p = 0.0006; HbAlc r = 0.665, p = 0.0004), and with PG at 30, 60 and 120 min after initiation of 75 g OGTT (GA, r = 0.584, p = 0.0035; r = 0.624, p = 0.0015; r = 0.510, p = 0.0129, respectively; HbA1c, r = 0.669, p = 0.0004; r = 0.624, p = 0.0011; r = 0.509, p = 0.0112, respectively). The area under the curve for PG during 75 g OGTT showed strong correlations with GA ( r = 0.625, p = 0.0008) and HbA1c ( r = 0.671, p = 0.0003). GA and HbA1c also correlated positively with serum pentosidine, demonstrating that GA provides a no less significant assay than HbA1c as a reflection of glycemic control in DM hemodialysis patients. However, HbA1c was apparently reduced in DM hemodialysis patients, as reflected by an increase in the GA/HbA1c ratio to 3.58 ± 0.62 (mean ± SD), suggesting underestimation of glycemic control by HbA1c. Conclusion GA and HbA1c exhibited similar correlations with PG during a 75 g OGTT. The dependence of GA, in contrast to HbA1c, on PG does not differ in DM hemodialysis patients from that reported for subjects with normal renal function, suggesting GA as a better marker of glycemic control in DM hemodialysis patients.

Rosiglitazone can be used for diabetes control in hemodialysis patients with hepatitis

Rosiglitazone can be used for diabetes control in hemodialysis patients with hepatitis

Glycated Albumin Is a Better Glycemic Indicator than Glycated Hemoglobin Values in Hemodialysis Patients with Diabetes

The significance of glycated albumin (GA), compared with casual plasma glucose (PG) and glycated hemoglobin (HbA(1c)), was evaluated as an indicator of the glycemic control state in hemodialysis (HD) patients with diabetes. The mean PG, GA, and HbA(1c) levels were 164.5 +/- 55.7 mg/dl, 22.5 +/- 7.5%, and 5.85 +/- 1.26%, respectively, in HD patients with diabetes (n = 538), which were increased by 51.5, 31.6, and 17.7%, respectively, compared with HD patients without diabetes (n = 828). HbA(1c) levels were significantly lower than simultaneous PG and GA values in those patients in comparison with the relationship among the three parameters in patients who had diabetes without renal dysfunction (n = 365), as reflected by the significantly more shallow slope of regression line between HbA(1c) and PG or GA. A significant negative correlation was found between GA and serum albumin (r = -0.131, P = 0.002) in HD patients with diabetes, whereas HbA(1c) correlated positively and negatively with hemoglobin (r = 0.090, P = 0.036) and weekly dose of erythropoietin injection (r = -0.159, P < 0.001), respectively. Although PG and GA did not differ significantly between HD patients with diabetes and with and without erythropoietin injection, HbA(1c) levels were significantly higher in patients without erythropoietin. Categorization of glycemic control into arbitrary quartile by HbA(1c) level led to better glycemic control in a significantly higher proportions of HD patients with diabetes than those assessed by GA. Multiple regression analysis demonstrated that the weekly dose of erythropoietin, in addition to PG, emerged as an independent factor associated with HbA(1c) in HD patients with diabetes, although PG but not albumin was an independent factor associated with GA. In summary, it is suggested that GA provides a significantly better measure to estimate glycemic control in HD patients with diabetes and that the assessment of glycemic control by HbA(1c) in these patients might lead to underestimation likely as a result of the increasing proportion of young erythrocyte by the use of erythropoietin.

Associations between Sympathetic Activity, Plasma Concentrations of Renin, Aldosterone, and Parathyroid Hormone, and the Degree of Intractability of Blood Pressure Control in Hemodialysis Patients

This study was designed to examine how such factors as hemodialysis parameters, body mass index, renin and aldosterone concentrations, sympathetic nervous activity, and parathyroid hormone concentrations are associated with the control of hypertension in hemodialysis patients. Hemodialysis patients (n=114) were grouped into four categories. Group 1 had normal BP without antihypertensive medication. Group 2 needed one antihypertensive drug, Group 3 needed combination of two or three categories of antihypertensive drugs without minoxidil. Group 4 needed more than three categories of antihypertensive drugs including minoxidil. Parathyroid hormone, β2-microglobulin, renin and aldosterone, epinephrine, norepinephrine, and hemodialysis parameters were measured. The fractional clearance of urea as Kt/V urea was significantly lower in Group 3 and Group 4 than in Group 2 (p<0.01). Concentrations of parathyroid hormone were significantly higher in Group 4 than the other groups (p<0.01). Pre-hemodialysis norepinephrine concentrations were significantly higher in Group 4 than the other groups (p<0.05). Traditional factors associated with hypertension did not seem to be relevant to the degree of hypertension in hemodialysis patients in the present study. In conclusion, poor Kt/V urea, elevated parathyroid hormone concentrations, and elevated concentrations of plasma norepinephrine seemed to be the factors that might be associated with control of hypertension in hemodialysis patients.

Rosiglitazone in Diabetes Control in Hemodialysis Patients With and Without Viral Hepatitis Infection

Thiazolidinedione (TZD) may provide an additional benefit of cardiovascular protection in diabetic patients through targeting of insulin resistance. However, use of a TZD is hampered by possible effects of fluid retention and hepatotoxicity. In this study we aimed to determine whether the risk of TZD-induced fluid retention or hepatic injury is higher in hemodialysis patients with persistent viral hepatitis infection. This was a prospective, cohort study on hemodialysis patients. Type 2 diabetic patients with A1C levels of >8% were followed for at least 12 months. Rosiglitazone was initiated at 2-4 mg/day. The primary outcome was the target A1C (<7%) achieved and dosages of rosiglitazone. Secondary outcomes included changes in lipid profile and inflammatory biomarkers. Safety evaluations were number of hypoglycemic episodes, changes in liver transaminase levels, cardiothoracic ratio (CTR), fluid status control during dialysis, and events of symptomatic heart failure. A total of 78 patients, including 15.4% (n = 12) hepatitis B surface antigen-positive and 16.7% (n = 13) anti-hepatis C virus (HCV)-positive patients, were enrolled. The mean follow-up period was 15.4 +/- 3.8 months. The diabetic response rate (A1C <7%) to rosiglitazone was 86.1%. The serum triglyceride level was reduced (194 +/- 112.5 to 168 +/- 88 mg/dl, P = 0.037) more significantly than the total cholesterol level (178 +/- 42.1 to 174 +/- 46.5 mg/dl, P = 0.13). High-dose rosiglitazone (8 mg/day) reduced the serum level of C-reactive protein and increased the serum adiponectin level significantly. After rosiglitazone, interdialysis weight gain (2.07 +/- 1.6 to 3.2 +/- 1.2 kg, P < 0.01) and mean CTR (48.2 +/- 5.6 to 50.4 +/- 6.2%, P = 0.0213) of individuals increased significantly. Nevertheless, liver aminotransferase (aspartate aminotransferase and alanine aminotransferase) levels did not show a tendency to increase in patients (n = 25) with viral hepatitis B or C infections. Among regular hemodialysis patients with chronic viral hepatitis infections, rosiglitazone may be safely used for diabetes control. However, one must be aware that a possible effect of its use is a deterioration in cardiovascular reserve.

Adequacy of Glycemic Control in Hemodialysis Patients With Diabetes

We sought to measure the prevalence of inadequate glycemic control in prevalent hemodialysis patients with diabetes and to examine independent predictors of inadequate glycemic control in these patients. This is a cross-sectional study of prevalent hemodialysis patients with diabetes in southeastern Ontario (n = 100). Data were collected by chart review and interview. The outcome variable was inadequate glycemic control defined as HbA1c (A1C) >0.07. Other measured variables were diabetes type, diabetes duration, diabetes physician, blood glucose monitoring, diabetes medications, BMI, time on dialysis, and other demographic, clinical, and laboratory variables. Fifty-four patients had A1C >0.07. In bivariate analysis, these patients had a longer diabetes duration (23.6 vs. 14.7 years, P < 0.001), higher proportion with insulin use (81.5 vs. 58.7%, P = 0.012), higher proportion with microvascular complications (66.7 vs. 43.5%, P = 0.017), and lower erythropoietin (EPO) dose (7.0 vs. 11.9 x 10(3) units/week, P < 0.01) than patients with adequate glycemic control. There was no difference between the two groups in terms of macrovascular complications (59.3 vs. 65.2%, P = 0.54). In multiple logistic regression controlling for age and diabetes type, the diabetes duration (odds ratio 1.09 [95% CI 1.04-1.15], P < 0.001), EPO dose (0.90 [0.85-0.97], P < 0.01), and blood glucose monitoring (10.06 [1.03-98.74], P = 0.05) were the only significant independent predictors of A1C >0.07. A high proportion of hemodialysis patients with diabetes had inadequate glycemic control, particularly those with longstanding disease. Patients with inadequate glycemic control had a significantly higher burden of microvascular complications.

CHAPTER 3

CHAPTER 3

Volume Status and Blood Pressure in Continuous Ambulatory Peritoneal Dialysis Patients

The pathophysiology of hypertension in dialysis patients is largely attributed to positive sodium balance and volume expansion. Whereas the relationship between fluid status and blood pressure control in hemodialysis patients is well established, this relationship is not well studied in peritoneal dialysis patients. Methods: 100 stable CAPD patients who had been dialyzed for more than 3 months, as well as 60 healthy controls, were studied cross-sectionally. CAPD patients were divided into three groups according to their blood pressure level: group 1 (normotension), group 2 (controlled hypertension with antihypertensive medication (AHM)) and group 3 (uncontrolled hypertension with AHM). Extracellular water (ECW) and intracellular water (ICW) were measured using bioimpedance spectroscopy in all subjects. Dialysis adequacy and transport test was conducted in each patient. Results: Height normalized ICW (nICW) was much lower, and ECW/ICW was higher in both male and female dialysis patients as compared to healthy controls. nECW was also significantly higher in group 3 when compared to group 1. The dose of AHM was similar in group 2 and group 3. In female CAPD patients, there were no differences in urinary volume (UV) and the total fluid removal among the three patient groups. However, in male CAPD patients, UV and total fluid removal were significantly higher in group 3 than in group 1. Renal and total removal of sodium was also significantly higher in group 3 male patients than group 1. Conclusions: Peritoneal dialysis patients with uncontrolled hypertension are more volume overloaded and their blood pressure may be difficult to control by AHM alone. These findings indicate that volume control preferably by dietary salt and fluid restriction should be intensified in hypertensive CAPD patients.

Time and exercise improve phosphate removal in hemodialysis patients

Background: Control of serum phosphate remains a difficult clinical issue in most hemodialysis (HD) patients. This study examines 2 nonpharmacological approaches to improving phosphate control in HD patients. Methods: First, 9 stable HD patients underwent dialysis in random fashion for either 4 hours 3 times weekly or 5 hours 3 times weekly. Adjustments were made to blood flow rates such that Kt/V was the same for all sessions, thus allowing independent assessment of the influence of time. The primary end point was weekly dialysate phosphate removal. In the second study, 12 different patients underwent an exercise program in which they pedaled a bicycle ergometer either immediately before or during dialysis. Again, weekly dialysate phosphate removal was measured. Results: In the time study, urea reduction ratio (69% ± 0.02% versus 68% ± 0.07, 4 versus 5 hours) and weekly urea removal were no different between the 2 groups. However, weekly phosphate removal (3,007 ± 641 versus 3,400 ± 647 mg; P < 0.02) significantly improved with longer dialysis duration. Serum phosphate levels improved, but did not reach statistical significance in this short-term study. In the exercise study, weekly phosphate removal improved with exercise, but did not reach significance (2,741 ± 715 [no exercise] versus 2,917 ± 833 [exercise predialysis] versus 2,992 ± 852 mg [exercise during dialysis]; P = 0.055), although comparing only exercise during dialysis with no exercise reached significance (P = 0.02). There was no significant difference in serum phosphate levels. Conclusion: Both increased dialysis time and exercise result in increased dialytic removal of phosphate and could be expected in the long term to improve phosphate control.

Pulse Pressure Determinants in Chronic Hemodialysis Patients

Cardiovascular disease is the leading cause of morbidity and mortality in end-stage renal disease. Hypertension contributes to the high cardiovascular morbidity in patients undergoing chronic hemodialysis therapy (PCHD). Optimal blood pressure (BP) in dialysis patients is not different from recommendations for the general population. The definition of hypertension in patients undergoing chronic hemodialysis therapy is still under debate. Predialysis systolic and diastolic BP is of particular importance. The mean arterial pressure (MAP) also serves as an expression of BP in hemodialysis patients, instead of systolic or diastolic BP. Investigations in the general population have demonstrated the predictive utility of pulse pressure (systolic minus diastolic blood pressure), a measure reflecting the pulsatile nature of the cardiac cycle. Recent recognition of pulse pressure (PP) as an important correlate of mortality in patients receiving dialysis highlights the need to investigate the relationship between PP and clinical outcomes in patients with end-stage renal disease. We conducted this study to demonstrate clinical and biochemical determinants of predialysis and postdialysis PP values during a 15-month period in a group of patients undergoing chronic hemodialysis therapy.

The Influence of Increasing Dialysis Treatment Time and Reducing Dry Weight on Blood Pressure Control in Hemodialysis Patients: A Prospective Study

A good blood pressure control can be achieved with long hemodialysis sessions (dialysis center of Tassin, France). However, it is not well known whether a higher dialysis dose or a lower dry weight is responsible for this phenomenon. In a preliminary study, 21 hypertensive dialysis patients, dialyzed three times a week for 3–5 h, were randomized into three groups during a 3-month study period. In 6 patients, the dialysis treatment time was increased by 2 h, and the dry weight was gradually decreased (group 1). In 7 patients the dialysis treatment time was increased by 2 h without a change in dry weight (group 2). In 8 patients the dry weight was gradually lowered without changing the dialysis treatment time (group 3). Before and after the study, cardiac index and left ventricular mass index (echocardiography) and forearm vascular resistance (strain gauge plethysmography) were determined on a middialytic day. The blood pressure was assessed by 48-hour ambulatory monitoring. The antihypertensive medication was reduced when the postdialytic blood pressure became <130/80 mm Hg. The dry weight was reduced by 2.6 ± 1.4 kg in group 1 and by 2.3 ± 0.8 kg in group 3 (p < 0.05). The number of classes of antihypertensive medication was reduced from 3.3 to 1.8 in group 1 (NS), from 2.4 to 1.7 in group 2 (NS), and from 3.1 to 1.3 in group 3 (p < 0.05). The dose of the remaining antihypertensive drugs was reduced by 50% in group 1 (p < 0.05), by 32% in group 2 (NS), and by 72.2% in group 3 (p < 0.05). The interdialytic systolic blood pressure decreased significantly after increasing the dialysis time without changing the dry weight (group 2: 7 ± 5 mm Hg; p < 0.05). The systolic blood pressure was also lower in the other patients groups: group 1: 13 ± 26 mm Hg, group 3 : 7 ± 16 mm Hg (NS). The pulse pressure decreased significantly in group 2 (7 ± 5 mm Hg; p < 0.05) and in group 3 (6 ± 7 mm Hg; p < 0.05) and tended to decrease in group 1 (11 ± 12 mm Hg; p = 0.08). The diastolic blood pressure and the day-night blood pressure difference did not change significantly, nor did cardiac index and left ventricular mass index. The forearm vascular resistance tended to decrease in the patients on long dialysis sessions. This preliminary study suggests that the dialysis treatment time might have an independent beneficial effect on blood pressure control.

New Approaches to the Physiological Blood Pressure Control in Hemodialysis Patients

Blood pressure instability is the most frequent complication of haemodia-lysis treatments. Individualised control of fluid removal, taking into account impaired physiological responses, is the key to improved stability. Heart rate and the function of the arterial vessels can be identified using a two model approach. An inverted heart model has been used to estimate venous pressure from cardiac output. A model of the closed circulatory system has facilitated the analysis of arterial and venous resistance in 12 patients. Both resistances were found to increase, reaching physiological levels only after heavy fluid reduction.

Volume Control in Hemodialysis Patients

Cardiovascular disease is the main cause of the high mortality of dialysis patients and is largely due to poor control of blood pressure. Establishing and maintaining normal extracellular volume (ECV) is required to achieve normotension. The dry weight concept links ECV and blood pressure by a simple clinical relationship. Dry weight is the ideal postdialysis weight that allows a constantly normal blood pressure to be maintained without using antihypertensive medications. Maintenance of normal ECV requires control of salt intake to reduce interdialytic weight gain ( i.e., saline overload) combined with the diffusive and convective removal of salt and water from the body during dialysis sessions. Several problems are to be faced when using the dry weight method. Clinical evaluation must take into account the following confounding factors: weight varies with nutrition, clinical symptoms are unspecific and sometimes discordant, and there is a lag time between ECV and blood pressure changes. On the other hand, achievement of dry weight is hampered by dialysis times that are too short (and weight gains that are too high), by antihypertensive medications, and by poor heart conditions. A longer session time allows for a slower, easier, and more comfortable ultrafiltration.