Total Convection Affects Serum ß2 Microglobulin and C-Reactive Protein but Not Erythropoietin Requirement following Post-Dilutional Hemodiafiltration.

BACKGROUND: Inflammation and increased erythropoiesis stimulating agents (ESA) requirement are frequently associated in patients on dialysis. On-line hemodiafiltration (ol-HDF), putting together high levels of diffusion, and convection could improve both conditions. However, it is still not known which depurative component plays a major role in determining this result. The aim of the study was to evaluate the role of convection and diffusion on long-term variations of serum ß2 microglobulin (Δß2M), high-sensitive C-reactive protein (ΔhsCRP) concentrations, and ESA requirement (ΔESA) in ol-HDF. METHODS: Seventy-three patients prevalent on high flux HD (hfHD) were studied. Thirty-eight patients were switched from hfHD to post-dilutional ol-HDF (Study group); the other 35 patients were considered the Control group. At 6 and 12 months, the effects of ol-HDF and hfHD on ΔhsCRP, ΔB2M, and ΔESA (U/kg/week) were evaluated. Other variables considered were body weight (BW), serum albumin (sAlb), hemoglobin (Hb), and equilibrated Kt/V (eKt/V). Iron therapy and ESA were administered intravenously according to the K/DOQI guidelines in order to maintain transferrin saturation between 20 and 40%, serum ferritin between 150 and 500 ng/ml and Hb between 11 and 12 g/dl. Qb, treatment time and Qd remained constant. Ol-HDF and hfHD were performed using membranes of size 1.9-2.1 sqm. Ultrapure dialysate and substitution fluid were employed in both HDF and HD treatments. Data are expressed as mean ± SD. Paired t test, Mann-Whitney U test, and simple and multiple regression analyses were employed for statistical evaluation. STUDY GROUP: total convective volume (TCV) was 22.1 ± 1.9 l/session. A significant reduction of hsCRP: from 6.8 ± 7.1 to 2.3 ± 2.4 mg/dl (p < 0.001), ß2M: from 36.5 ± 14.4 to 24.7 ± 8.6 mg/dl (p < 0.0001) and ESAdose: from 107 ± 67 to 65 ± 44 U/kg/week (p < 0.005) was observed. No significant variations of Hb, BW and sAlb were seen. A significant inverse correlation was found between TCV and Δß2M (r = -0.627; p < 0.0001), and TCV and ΔhsCRP (r = -0.514; p < 0.0001); no correlation between TCV and ΔESAdose was observed. No correlation was found between eKt/V and Δß2M, ΔhsCRP, and ΔESAdose. Multiple regression analysis with ΔESAdose as dependent variable showed ΔhsCRP as the only significantly associated independent factor (p < 0.01). CONTROL GROUP: no significant variations of hsCRP, ß2M, and ESAdose were observed over time. CONCLUSIONS: Ol-HDF induces a long-term significant reduction in pre-dialysis ß2M and hsCRP concentrations. The magnitude of reduction is directly correlated to the amount of TCV achieved but not on eKt/V. The observed reduction in ESAdose requirement is independent either on convection or diffusion, but is directly associated to the concomitant reduction of inflammation.

Role of dialysis sodium gradient on intradialytic hypertension: an observational study.

INTRODUCTION: The causes of intradialytic hypertension (IDHyper) are not well understood and this condition can complicate the clinical management of hemodialysis (HD) patients. AIM: To evaluate the potential role of intradialytic sodium gradient (NaG) on blood pressure values and IDHyper during HD. PATIENTS AND METHODS: 206 prevalent HD patients on 3 times weekly HD treatment for at least 6 months (dialytic vintage 6-240 months) followed at our institution were studied. Mean age was 68 ± 14 years, 129 were men. For 2 consecutive months (24 HD sessions) after the start of observation, the following variables were evaluated in predialysis after the long interdialysis interval: pre-HD plasma sodium (pNa, mmol/l) and potassium (pK, mmol/l) concentrations (mean value of 8 determinations), pre- and post-HD systolic (SBP, mm Hg) and diastolic (DBP, mm Hg) blood pressure, dry body weight (dBW, kg), interdialytic weight gain (IDWG, kg), ultrafiltration rate (UFR, ml/kg/h), dialysis dose (Kt/V), protein catabolic rate (PCRn, g/kg/day), hemoglobin (Hb, g/dl). SBP, DBP, IDWG, UFR are the mean values of the 24 HD sessions. 76% of patients were on antihypertensive therapy, 171 patients were on bicarbonate HD, and 35 on HDF. Dialysate Na concentration was set at 140 mmol/l in all patients. Duration of HD and the blood and dialysate flow rate were kept constant during observation. STATISTICAL ANALYSIS: Data are expressed as mean ± SD; linear and multiple regression analysis and t test for unpaired data were employed. Significant differences were defined as p < 0.05. RESULTS: Pre-HD pNa was 138.1 ± 2.3 mmol/l, pK 5.0 ± 0.4 mmol/l, dBW 67 ± 14 kg, IDWG 2.9 ± 0.8 kg, UFR 11.2 ± 3.7 ml/kg/h, Kt/V 1.43 ± 0.18, PCRn 1.13 ± 0.17 g/kg/day, and Hb 11.2 ± 0.8 g/dl. Pre- and post-HD SBP values were 139 ± 13 and 134 ± 12 mm Hg (p < 0.0001); pre- and post-HD DBP did not change significantly. A dialysis Na gradient (NaG) (dialysate Na - pre-HD pNa) was calculated, as well as the delta of SBP (ΔSBP) (post-HD SBP - pre-HD SBP). IDHyper was defined as ΔSBP >0. A significant direct correlation was found between NaG and ΔSBP (p < 0.0001) and multiple regression analysis with ΔSBP as dependent variable confirmed the strong correlation with NaG (p < 0.00001). According to ΔSBP behavior, 171 patients (83%) had a decrease or no change in post-HD SBP (group 1; no IDHyper); 35 patients (17%) increased their post-HD SBP (group 2; IDHyper). NaG values were significantly greater in patients in group 2 (group 1: 1.5 ± 2.2 vs. group 2: 3.3 ± 2.5, p < 0.0001). CONCLUSIONS: This study shows that the intradialytic ΔSBP is independently and strongly associated with the dialytic NaG. The more positive the NaG (net intradialytic Na gain), the more positive the ΔSBP and IDHyper.

Magnitude of end-dialysis overweight is associated with all-cause and cardiovascular mortality: a 3-year prospective study.

BACKGROUND: We hypothesized that the difference between the prescribed end-dialysis body weight, defined end-dialysis over-weight (edOW; kg), and the body weight which is actually attained could impact survival in hemodialysis (HD) patients. The aim of this prospective observational study was to evaluate if edOW could influence survival in a cohort of prevalent HD patients, controlled for multiple dialysis and clinical risk factors and followed for 3 years. METHODS: One hundred and eighty-two patients (117 men, age 65 ± 13 years) on regular HD treatment for at least 6 months [median 48 months (range: 6-366)] were followed from January 1, 2008 to December 31, 2010. Eighty-four patients (46%) did not achieve their prescribed dry body weight (dBW); their median edOW was 0.4 kg (range: 0.1-1.4). Ninety-eight died during observation, mainly from cardiovascular reasons (69%). Multivariate Cox regression analysis was utilized to evaluate the effect edOW, ultrafiltration rate (UFR), interdialytic weight gain (IDWG), age, sex, dialytic vintage, cardiovascular disease, antihypertensive therapy, diabetes, duration of HD, dBW, BMI, mean arterial blood pressure, Kt/V, and protein catabolic rate (PCRn) had on mortality. RESULTS: Age (HR: 1.04; CI: 1.03-1.05; p <0.0001), IDWG (HR: 2.62; CI: 2.06-3.34; p < 0.01), UFR (HR: 1.13; CI: 1.09-1.16; p< 0.01), PCRn (HR: 0.02; CI: 0.01-0.04; p <0.001), and edOW (HR: 2.71; CI: 1.95-3.75; p < 0.02) were independently correlated to survival. The relative receiver operating characteristic curve identified a cutoff value of 0.3 kg for edOW in predicting death. CONCLUSIONS: High edOW is independently associated with an increased long-term risk of all-cause and cardiovascular mortality in HD patients. Better survival was observed in patients with edOW <0.3 kg. For patients with higher edOW, longer or more frequent dialysis sessions should be considered in order to prevent the deleterious consequences of excessive body fluid expansion.