Residual renal function and arterial stiffness mediated the blood pressure change during interdialytic weight gain in hemodialysis patients

Volume overload is thought to be the main cause of hypertension in dialysis patients. However, the effect of interdialytic weight gain (IDWG) in hemodialysis (HD) patients, which was considered as an increase in extracellular water (ECW), on blood pressure (BP) change, was controversial. Our aim was to examine the changes in hemodynamics and arterial stiffness during IDWG in HD patients and attempt to explore the possible mechanism of diverse BP change. Thirty prevalent patients on HD were enrolled. The height, weight, BP, blood chemistry, volume status assessed by bioelectrical impedance analysis, hemodynamic parameters obtained by echocardiography, and pulse wave velocity (PWV) were collected within 1 hour postdialysis and again just before the next dialysis session. Meanwhile, blood samples were drawn to analyze vasoactive hormones, including renin, angiotensin II, catecholamine, and endothelin. The patients' weights and ECWs during the next predialysis were significantly higher than those during the postdialysis. The BP showed no difference between postdialysis and the next predialysis. There was an obvious increase in cardiac output and decrease in total peripheral resistance as a whole during the next predialysis than that during postdialysis. When patients were divided into the BP increase group (BPI group, 13 patients) and BP decrease group (BPD group, 11 patients) according to the change in systolic BP higher than 10 mmHg, both groups displayed a significant increase in weight, ECW, cardiac output, and a decrease in total peripheral resistance. As compared with the BPI group, patients in the BPD group had significantly lower IDWG, shorter time on dialysis treatment, and higher residual renal function. A decrease in catecholamine and endothelin in the next predialysis was obvious in the BPD group. There was a significant decrease in PWV at the next predialysis in the BPD group while the PWV did not change significantly in the BPI group. Our results showed that the diverse BP change during IDWG was significantly affected by residual renal function, PWV, and vasoactive substances.     

Cardiovascular conditions in hemodialysis patients may be worsened by extensive interdialytic weight gain

The risk of death is increased for hemodialysis (HD) patients compared with age-matched healthy subjects, the main reason for this being cardiovascular conditions. This prospective study investigated whether the burden of interdialytic weight gain (IDWG) was of importance for cardiovascular end points and survival. A total of 97 HD patients were studied. The end points included death (reasons given), acute myocardial infarction, or coronary vascular intervention. The extent of ultrafiltration was measured at predefined follow-up points. The IDWG was calculated as ultrafiltration/body weight given in weight%. The burden of IDWG was analyzed. End points occurred in 77 (79%) of the patients during the 5-year study period. The extent of IDWG was higher in those with end points due to cardiovascular reasons (3.77 weight% vs. 3.19 P<0.001), cardiac reasons (P<0.001), congestive heart failure (P<0.01), aortic aneurysm, and intracerebral bleeding (P<0.024). To reduce the risk for cardiovascular events, it is important to avoid too extensive IDWG in HD patients.     

Dialysate bicarbonate variation in maintenance hemodiafiltration patients: Impact on serum bicarbonate,intradialytic hypotension and interdialytic weight gain

Introduction: The dialysate bicarbonate (DB) influences the acid‐base balance in dialysis patients. Very low and high serum bicarbonate (SB) have been related with a higher mortality. Acid‐base balance also has been associated with hemodynamic effects in these patients. The trial aim was to compare the effect of DB concentration variation on SB levels in maintenance hemodiafiltration (HDF) patients and the effect on intradialytic hypotension and interdialytic weight gain. Methods: A prospective study, with 9 months of follow‐up, involving 93 patients, divided in two groups: group 1 and group 2 with a DB of 34 mmol/L and 30 mmol/L, respectively, with monitoring of pre and post HDF SB, intradialytic hypotension, and interdialytic weight gain. Findings: Pre dialysis SB was higher in group 1: median concentration of 22.7 mmol/L vs. 21.1 mmol/L (P < 0.001). Post dialysis SB levels were higher in group 1: median concentration of 28.0 mmol/L vs. 25.3 mmol/L (P < 0.001). Post dialysis SB in alkalotic range was only detected in group 1 (51.2% of the patients). No significant differences were detected in intradialytic hypotension rate [28.0 vs. 27.4 episodes per 1000 sessions in group 1 and 2, respectively, (P = 0.906)] or in average interdialytic weight gain [2.9% vs. 3.0% in group 1 and 2, respectively, (P = 0.710)]. Discussion: DB of 30 mmol/L appears to be associated with SB levels closer to physiological levels than 34 mmol/L. The bicarbonate dialysate, in the tested concentrations, did not appear to have a significant impact on intradialytic hypotension and interdialytic weight gain in maintenance HDF patients.     

Stimulated sweating as a therapy to reduce interdialytic weight gain and improve potassium balance in chronic hemodialysis patients: A pilot study

Controlling the extracellular volume in hemodialysis patients is a difficult task. The aim of this study was to evaluate the capacity of different methods of stimulated sweating to reduce mean interdialytic weight gain (IWG), to improve blood pressure regulation, and potassium/urea balance. Two center, crossover pilot study. In Lausanne, hemodialysis patients took four hot‐water baths a week, 30 minutes each, on nondialysis days during 1 month. In Sfax, patients visited the local Hammam Center four times a week. Hemodynamic parameters were recorded, and weekly laboratory analysis was performed. Results were compared with a preceding 1‐month control period. In Lausanne, five patients (all men, median age 55 years) participated. Bathing temperature was (mean ± standard deviation) 41.2 ± 3°C and sweating‐induced weight loss 600 ± 500 g. Mean IWG (control vs. intervention period) decreased from 2.3 ± 0.9 to 1.8 ± 1 kg (P = 0.004), Systolic blood pressure from 139 ± 21 to 136 ± 22 mmHg (P = 0.4), and diastolic blood pressure form 79 ± 12 to 75 ± 13 mmHg (P = 0.08); antihypertensive therapy could be reduced from 2.8 ± 0.4 to 1.9 ± 0.5 antihypertensive drugs per patient (P = 0.01). In Sfax (n = 9, median age 46 years), weight loss per Hammam session was 420 ± 100 g. No differences were found in IWG or BP, but predialysis serum potassium level decreased from 5.9 ± 0.8 to 5.5 ± 0.9 mmol/L (P = 0.04) and urea from 26.9 ± 6 to 23.1 ± 6 mmol/L (P = 0.02). Hot‐water baths appear to be a safe way to reduce IWG in selected hemodialysis patients. Hammam visits reduce serum potassium and urea levels, but not IWG. More data in larger patient groups are necessary before definite conclusion can be drawn.     

A meta‐analysis of sodium profiling techniques and the impact on intradialytic hypotension

Introduction Hemodialysis has improved in recent years, however, despite such improvements, intra‐dialytic hypotensive episodes still persist which can lead to a reduction in the overall effectiveness of the treatment. Profiling sodium levels during dialysis can improve vascular refilling and therefore may prevent hypotensive events. A number of profiling methods exist and this meta‐analysis set out to examine the effectiveness of these methods. Methods To assess the effectiveness of hemodialysis sodium profiling techniques. A review and meta‐analysis analytical framework was used. A search was conducted using Medline, Embase and CINAHL, Scopus and Web of Knowledge between 1946 and 2014 of published English‐language peer reviewed randomized control studies. In total 10 articles were retrieved and included in the review. All data was abstracted with a standardized data collection form. Stata 11.2 (Stata Corp) was used to analyse the data. Actual numbers of hypotensive events were pooled between studies. Analysis of subgroups was performed on sodium profile type. The data were further investigated using meta‐regression. Publication bias was also tested. Findings Stepwise profiling was shown to be statistically significantly effective in reducing intradialytic episodes. Results demonstrated that linear sodium profiling was not effective in reducing hypotensive events during dialysis. Discussion This review has shown that using stepwise profiling is more effective at reducing intra‐dialytic symptoms than other profiling methods. There was no evidence that linear profiling method was any more effective than conventional dialysis and in fact the results showed the reverse.     

Hypoalbuminemia is an important risk factor of hypotension during hemodialysis

Hypotension during hemodialysis (HD) is an important problem in patients on HD. To investigate the risk factors that contribute to the hypotension during HD, we compared background factors of hypotensive (HP) patients during HD. Among 58 patients undergoing HD in Tamura Memorial Hospital, 12 patients could not continue full HD because of hypotension. We compared the data of ultrafiltration volume, cardiothoracic ratio (CTR), total protein (TP), serum albumin, blood urea nitrogen (BUN), serum creatinine, total cholesterol (TC), hemoglobin (Hb), blood glucose (BS), brain natriuretic peptide (BNP), and cardiac function between HP patients (HP group; n=12) and sex- and age-matched control patients (NP group; n=12). There were no significant differences of age, sex, and duration of HD between the 2 groups. Cardiothoracic ratio is bigger and BNP is higher in the HP group compared with the NP group (CTR: HP 55.8+/-2.9% vs. NP 47.7+/-1.1%, p=0.0165; BNP: HP 602+/-171 vs. NP 147+/-38, p=0.0167). Serum albumin in the HP group is significantly lower compared with the NP group (HP 3.2+/-0.1 g/dL vs. NP 3.5+/-0.1 g/dL, p=0.0130). However, there were no significant differences of ultrafiltration rate (UFR), BS, TC, Hb, and cardiac function between the 2 groups. There is a significant negative correlation between changes of systolic blood pressure (delta systolic blood pressure) and serum albumin in these patients (r=-0.598, p=0.0016). From these data, we conclude that hypoalbuminemia is a major risk factor of hypotension during HD.     

Adrenal insufficiency presenting as unexplained hypotension in nocturnal home hemodialysis

Adrenal insufficiency is a complication of chronic corticosteroid therapy. Unexplained hypotension may be a manifestation of an adrenal insufficient state in patients with a history of corticosteroid therapy on hemodialysis. We present a series of five cases of patients on nocturnal home hemodialysis with hypotension as the main manifestation of adrenal insufficiency. Unexplained hypotension in patients with a history of corticosteroid therapy should prompt the managing clinician to consider adrenal insufficiency as a possible cause.     

Intradialytic complications during hemodialysis

With the advent of developments and advances in hemodialysis machine technology, dialysate water purification, and dialyzers, the clinical spectrum of intradialytic complications has changed over the decades. In the pioneering days of hemodialysis, patients could develop allergic reactions to dialyzer membranes, sterilizing and reprocessing agents, coupled with machines that could not accurately control ultrafiltration rates, and chemically and bacterially contaminated dialysate. Whereas today, although cardiovascular problems remain the most common intradialytic complication, these are mainly due to the time restraints of trying to cope with excessive dialytic weight gains and achieve target dry weight on a thrice weekly schedule, coupled with an aging elderly dialysis population with increasing co-morbidity.     

Predictors of anemia in patients on hemodialysis

Even though the use of erythropoietin and intravenous iron has improved the treatment of anemia in hemodialysis patients, a considerable proportion of these patients still have anemia. The aim of this study was to identify predictors of anemia in a hemodialysis population. In a single-center hemodialysis unit, all patients were studied with blood tests and their medication recorded during a period of 22 months. Correlations with hemoglobin (Hb) were performed with a simple regression or a t test. Variables that reached 5% significance were entered in a multiple regression analysis. Selected variables were presented in quartiles with levels of Hb. Mean Hb was 11.3 g/dL, and 53 patients (40%) had Hb<11.0 g/dL. In the simple regression analysis Hb correlated positively with s-iron, CHr, s-albumin, and doses of sevelamer, and negatively with sedimentation rate (SR), ferritin, base excess, and doses of erythropoietin. In the multiple regression analysis erythrocytes SR was the only variable that remained significant. Elevated SR is the strongest predictor of anemia in hemodialysis patients receiving adequate treatment with erythropoietin and intravenous iron. Patients using high doses of sevelamer had higher Hb levels than patients using low doses.     

Effects of secondary amyloidosis on arteriovenous hemodialysis fistula outcomes and intradialytic hypotension: a case-control study

Amyloid fibrils can affect vascular structure through deposition and by causing nitric oxide depletion and increase of asymmetric dimethyl arginine. Patients with amyloidosis are prone to development of hypotension. Hypotension may also affect the maturation of arteriovenous fistula (AVF) and may set the stage for formation of thrombosis and fistula failure. Thus, we aimed to evaluate effects of secondary amyloidosis on AVF outcomes and intradialytic hypotension. This is a case‐control study which included 20 hemodialysis patients with amyloidosis and 20 hemodialysis patients without amyloidosis as control group. All patients underwent Doppler ultrasound of AVF. A thorough fistula history and baseline laboratory values along with episodes of intradialytic hypotension and blood pressure measurements were recorded. There was no difference between the groups regarding age, gender, body mass index, presence of comorbidities, hypertension, and drug use. Systolic and diastolic blood pressures were similar (119 ± 28/75 ± 17 and 120 ± 14/75 ± 10 mmHg for patients with and without amyloidosis, respectively). Intradialytic hypotension episodes were also similar. Patients with amyloidosis had significantly lower serum albumin and higher C‐reactive protein values compared to control hemodialysis patients. AVF sites and total number of created fistulas were similar in both groups. Flow rates of current functional AVFs were not different between the groups (1084 ± 875 and 845 ± 466 mL/minute for patients with and without amyloidosis, respectively, p:0.67). Patency duration of first AVF was not different between the groups. Clinical fistula outcomes and rate of intradialytic hypotension episodes were not significantly different between patients with and without secondary systemic amyloidosis.     

Effect of phosphate binders on oxidative stress and inflammation markers in hemodialysis patients

It has been suggested that phosphate binders may reduce the inflammatory state of hemodialysis (HD) patients. However, it is not clear whether it has any effect on oxidative stress. The objective of this study was to evaluate the effect of sevelamer hydrochloride (SH) and calcium acetate (CA) on oxidative stress and inflammation markers in HD patients. Hemodialysis patients were randomly assigned to therapy with SH (n=17) or CA (n=14) for 1 year. Before the initiation of therapy (baseline) and at 12 months, we measured in vitro reactive oxygen species (ROS) production by stimulated and unstimulated polymorphonuclear neutrophils and serum levels of tumor necrosis factor α, interleukin-10, C-reactive protein, and albumin. There was a significant reduction of spontaneous ROS production in both groups after 12 months of therapy. There was a significant decrease of Staphylococcus aureus stimulated ROS production in the SH group. There was a significant increase in albumin serum levels only in the SH group. In the SH group, there was also a decrease in the serum levels of tumor necrosis factor α and C-reactive protein. Our results suggest that compared with CA treatment, SH may lead to a reduction in oxidative stress and inflammation. Therefore, it is possible that phosphate binders exert pleiotropic effects on oxidative stress and inflammation, which could contribute toward decreasing endothelial injury in patients in HD.     

A study of the extracorporeal rate of blood flow and blood pressure during hemodialysis

Hemodynamic instability is a common problem during hemodialysis (HD). The effect of blood flow rate (BFR) on blood pressure (BP) during HD has not been previously evaluated. Subjects receiving HD for the treatment of renal failure were enrolled (n=34). For each patient, during the last hour of 2 consecutive HD sessions the BFR was set at 200 mL/min for 30 min and at 400 mL/min for 30 min, during which period the fluid removal rate was kept constant. The order of the BFR alterations was randomized. The study procedure was repeated during the next HD session but with reversal of the order of the altered BFR. During each 30-min period, BP was recorded at baseline and subsequently every 10 min. During the BFR of 400 mL/min, subjects had a higher systolic BP by an average of 4.1 mmHg compared with the BFR of 200 mL/min (95% confidence interval [CI] 0.22-7.98; p=0.038). Similarly, during the BFR of 400 mL/min, subjects had a higher diastolic BP by an average of 3.04 mmHg compared with the BFR of 200 mL/min (95% CI 0.55-5.53; p=0.017). Likewise, during the BFR of 400 mL/min, subjects had a higher mean arterial pressure by an average of 3.44 mmHg (95% CI 0.77-6.11; p=0.012). The findings suggest that during HD, BPs are maintained higher at higher BFRs as compared with lower BFRs.     

Death during hospitalization in patients on chronic hemodialysis

Mortality from various causes is higher in patients on chronic hemodialysis (HD) than in the general population. There is evidence suggesting that some of the deaths in HD patients are preventable. To identify potentially preventable causes of death, we analyzed deaths that occurred in HD patients during hospitalization over a period of 15 years. We performed a retrospective cohort analysis of 410 patients on HD for at least 6 months between 1995 and 2009 (included), who had all their hospitalizations in the same hospital. The patients were classified into 3 groups: Those who died during hospitalization (group A, n=120), those who died away from the hospital (group B, n=135), and those who were alive at the end of the observation period (group C, n=155). Continuous variables were compared between groups by the Kruskall-Wallis statistic. Logistic regression was used to identify predictors of dying during the observation period and predictors of death in the hospital. For the whole HD group of 410 patients, only 9 (2.2%) were women. 59% of the patients had diabetes mellitus. Age at the onset of HD was 65.8 ± 11.5 years and the duration of HD was 34.4 ± 27.9 months. Group A patients had a higher annual rate and duration of hospitalization and a higher Charlson comorbidity index than either of the other 2 groups, and, in comparison with patients in group C, were older at the end of observation and had a shorter duration of HD. Cardiac disease (19.2%), vascular access complications (18.3%), peripheral vascular disease (16.7%), infections (15.8%), trauma (11.7%), central nervous system disease (7.5%), respiratory failure (4.2%), malignancy (3.3%), and gastrointestinal disease (3.3%) were the causes of the last hospitalization in group A. Compared with the patients who died during hospitalization without discontinuing HD, group A patients who discontinued HD had a longer duration of their last hospitalization (52.7 ± 77.7 vs. 14.3 ± 23.8 days, P<0.001). Discontinuation of HD occurred in 80% of the hospitalizations for respiratory failure, 75% of the hospitalizations for malignancy, 57% of the hospitalizations for trauma, and 56% of the hospitalizations for central nervous system disease. Logistic regression identified a high Charlson index, advanced age, and short duration of HD as predictors of death, and an absence of diabetes, high Charlson index, prolonged annual duration of hospitalization, and short distance of the patient's domicile from the dialysis unit as predictors of death in the hospital. A substantial number of hospitalizations leading to the death of HD patients are caused by potentially preventable conditions, including vascular access complications, peripheral vascular disease, and trauma. Implementation of measures preventing these hospitalizations is a worthwhile undertaking.