Response of the vascular system to different modifications of haemofiltration and haemodialysis.

In order to evaluate the reasons for the better tolerance of the cardiovascular system to body fluid removal in HF, different modifications of single-pass and recirculation HD as well as post-dilution HF were applied in 6 patients with stable chronic renal insufficiency under identical conditions of fluid removal, Curea and use of dialysers. A remarkable tolerance of the vascular system could be observed in HF as in HD when the Na+ concentration in the dialysis or diluting fluid was raised from 130 to 150mEq/L or when plasma osmotic pressure was stabilised by i.v. infusion of mannitol. The different buffers acetate and lactate did not influence the results specifically. Total peripheral resistance and plasma noradrenaline levels increased in HF but showed no changes in HD. Important factors causing the greater tolerance of the cardiovascular system in HF may be a more stable extracellular osmotic pressure, inducing a rapid refilling of the extracellular space, combined with an increasing total peripheral resistance.