How to prevent vascular instability: haemofiltration.

Most investigators agree that the remarkable tolerance of the vascular system to fluid withdrawal by haemofiltration is one of the most important advantages of this method. On the other hand it has been shown that blood pressure can be normalised in patients with dialysis-resistant hypertension by applying haemofiltration. The preservation of extracellular osmotic pressure during haemofiltration, obviously caused by the maintenance of a relatively high extracellular Na+ concentration, may induce a rapid and effective refilling of this compartment thus preventing vascular instability. A concept which may explain the apparently contradictory effect of haemofiltration on hypo- and hypertension, is proposed.