Does increasing haemoglobin concentration and haematocrit have a pressor effect in dialysis patients?

The haemodynamic consequences of differing rates of rise of haemoglobin and haematocrit in haemodialysis and CAPD patients were examined. Pre-dialysis mean arterial pressure, weight and haematological indices were recorded in 100 established haemodialysis patients prior to a 2-unit blood transfusion and repeated, pre-dialysis, within 1 week. Haemoglobin rose from 6.7 +/- 0.2 to 9.3 +/- 0.1 g/dl, weight was unchanged, and there was a small fall in mean arterial pressure. Similar indices were recorded, including the mid-arm circumference (MAC) in 100 CAPD patients 1 month after starting CAPD and at the time of maximum haemoglobin within the first year. Haemoglobin rose from 8.5 +/- 0.1 to 10.7 +/- 0.1 g/dl, weight increased slightly, but there was no change in MAC: weight ratio and there was a small fall in mean arterial pressure. In neither group was there a change in antihypertensive medication. In conclusion, increasing the haemoglobin concentration and haematocrit of dialysis patients within the range described in this study did not promote elevated blood pressure.