BLOOD-PRESSURE CONTROL AND HEMODYNAMIC-CHANGES IN PATIENTS ON LONG-TIME DIALYSIS TREATMENT

In dialysis patients blood pressure can be well controlled with long d ialysis (3 times a week for sh) in contrast to a more common short dia lysis regime (3 times a week for 4 h). We studied whether the good blo od pressure control in patients on long dialysis as compared to patien ts on short dialysis was associated with a decrease in extracellular f luid volume. Two-day interdialytic ambulatory blood pressure monitorin g was performed in 26 non-diabetic patients on long dialysis, in 22 pa tients on short dialysis, matched for:he years they were on dialysis t reatment, and during 24 h in 19 healthy volunteers. After full equilib ration, 24 h after dialysis, echography of the inferior caval vein was performed to determine fluid state. Cardiac dimensions and stroke ind ex were measured by echocardiography. A blood sample was drawn for the determination of electrolytes and vasoactive hormones. 73% of the pat ients on short dialysis were using antihypertensive medication in cont rast to none of the patients on long dialysis. However, blood pressure was significantly lower in patients on long dialysis (115 +/- 21/67 /- 11 mm Hg) when compared to patients on short dialysis (143 +/- 26/8 1 +/- 16 mm Hg). Indexed caval vein diameter, left ventricular diamete r index: and atrial natriuretic peptide were not significantly differe nt in patients on long dialysis compared to patients on short dialysis . Also the cardiac index was comparable in patients on long and short dialysis. However, the total peripheral resistance index was significa ntly lower in patients on long dialysis compared to the patients on sh ort dialysis and normal controls. The left ventricular mass index was increased in both patients on long and short dialysis compared to cont rols. We conclude that patients on long dialysis have adequate blood p ressure control that seems mainly to be caused by a low total peripher al resistance. These data also suggest that factors other than a lower fluid state contribute to the good blood pressure control in patients on long dialysis.