Blood pressure response to hemodialysis

Blood pressure response to hemodialysis was investigated in 15 patients with end-stage kidney disease; mean arterial pressure was unchanged in five (Group 1) and reduced 10 mm Hg in 10 (Group 2). The two groups did not differ significantly with regard to either biochemical values or hemodynamic indices before dialysis, and both sustained comparable reduction in body weight, total blood volume, and cardiac output following dialysis. Heart rate remained unchanged in both. The only significant difference between the two was the response of total peripheral resistance (TPR) to fluid depletion. TPR rose adequately in Group 1 but was unchanged in Group 2 (7.5 +/- 2.2 (SE) vs 0.7 +/- 1.1 units, p less than 0.025) despite equal fall in cardiac output in both (881 +/- 212 vs 890 +/- 173 ml/m, p less than 0.10). Thus, differences in arterial pressure response to fluid loss by hemodialysis could be due to impaired autonomic control of resistance vessels; this abnormality might not be revealed by tests of baroreceptor activity that depend only on heart rate responses to blood pressure variations.