Hemodynamic and Body Composition Changes Following Bilateral Nephrectomy in Chronic Renal Failure

Six patients with severe chronic renal failure and hypertension were evaluated before and again 1 and 4 months following bilateral nephrectomy while being maintained with regular hemodialysis. Hemodynamic function and body composition were measured by isotope dilution with each study. The mean femoral artery blood pressure (B.P.) of 142 mm Hg fell to 136 mm Hg (P, NS) at 1 month and to 120 mm Hg at 4 months (P < 0.005). This was mainly reflected in a drop in mean diastolic pressure of 13 mm Hg at 4 months (P<0.025). Total peripheral resistance tended to decrease, whereas, cardiac index was unchanged. Four months after nephrectomy, however, ability to raise both cardiac output and mean B.P. with standardized exercise had increased (P<0.005).Changes in exchangeable Na+, K+, extracellular fluid, and total body water did not correlate with the change in B.P. Plasma volume showed a slight tendency to fall with the decrease in mean B.P. after nephrectomy despite constant body weight (P<0.1). It is concluded that bilateral nephrectomy has a salutary effect on the hypertension of chronic renal failure (CRF), that this effect may not be immediately apparent, and that the fall in B.P. is independent of marked changes in extracellular fluid and exchangeable Na+ and plasma volume.