[Determination of brain natriuretic peptide in patients undergoing different haemodiafiltration techniques]

IB-type natriuretic peptide is a cardíac neurohormone secreted by the cardíac ventricules in response to ventricular dilatation so plasma BNP level correlate with left ventricular mass and dysfunction. Dialysis patients have much greater levels of BNP due to the volume overload and because of reduced renal clearance. The aim of this study was to mesure and compare the BNP levels in three groups of patients who received different hemodiafiltration techniques: Daily online hemodiafiltration (HDFOLd), on-line hemodiafiltration (HDFOL) and low convective volume hemodiafiltration (HDF). Fifteen patients were included, five in each group. Pre and postdialysis BNP leves were measured during 8 weeks. The measure was done at the beginning of the week (long period), and at the end (short period), in order to study if there were significative differences between techniques and periods. We found significative differences between predialysis BNP levels in the short period (BNPpreC) and the long period (BNPpre-L). We also found significative differences with the posdialysis BNP in both periods; BNPpre- L vs. BNPpos-L (1069+/-1031 vs. 612 +/- 540). After comparing the three techniques the study showed significative differences between BNPpreC in HDF and HDFOL compared with HDFOld. And also after dialysis between BNPpos-C in HDFOLd compared with the other techniques.

Although previous papers have shown that BNP levels have limited potential for assessment of hydration in hemodialysis patients, in this study our data demonstrate that after dialysis BNP levels decline in a significative way in the long and short period and we have found that patients on daily hemodialysis show lower BNP levels, and maybe this could be explained because daily on-line haemodiafiltration patients had lower weight rise between dialysis sessions and also better haemodynamic tolerance.