[Influence of blood pressure control on maintenance of residual function in patients treated by haemodialysis].

Introduction: Residual renal function (RRF) in the patients treated by haemodialysis (HD) is associated not only with better volume and blood pressure control but also with better metabolic control.The condition of the cardiovascular system significantly affects RRF.

Objective: The aim of the study was to find if there was any association between blood pressure regulation and the achieved HD ultrafiltration in the first year of haemodialysis treatment and the maintenance of RRF.

Methods: In this retrospective study, 53 patients were analyzed in the period 1994-2002. Residual clearance of urea (RCU) was measured for the first time at the beginning of HD treatment, and for the second time one year later. Laboratory data and values of blood pressure as well as the achieved HD ultrafiltration were taken from the electronic database of the Nephrology Hospital.

Results: The value of RCU less than 1 ml/min was considered as the loss of RRF and, at the beginning of HD treatment, 14 patients (26.4%) had that result. The rise of mean arterial pressure (MAP) was associated in linear regression analysis with a drop of residual diuresis volume (beta = -0.28; p = 0.04), but there was no association with RCU. The patients with MAP > 105 mm Hg had RKU less than the patients with MAP < 105 mm Hg (t = 2.23; p = 0.03). The rise of the HD ultrafiiltration significantly affected the loss of RRF obtained by the linear regression analysis (beta = -0.44; p = 0.0001).

Conclusion: The greater HD ultrafiltration is related to a drop of RCU values. Only prospective randomised trials with the use of multiple regression analysis could define a more precise association between hypertension and RKU.