AJP - Heart and Circulatory Physiology, Vol 247, Issue 2 229-H236, Copyright © 1984 by American Physiological Society
Hemodynamic response to volume depletion in acutely uremic dogs
J. T. Daugirdas, T. S. Ing, W. T. Chen, R. E. Vestal, J. L. Izzo Jr, J. E. Hano and M. J. Norusis
Hemodynamic response to volume depletion by isolated ultrafiltration was
compared in uremic (U) and nonuremic (N) conscious dogs. Fluid was removed
at a constant rate until mean arterial pressure (MAP) decreased to less
than 80 mmHg. Initial MAP was higher in the uremic dogs [132 +/- 8.6 (SD)
mmHg] than in nonuremic controls (106 +/- 12, P less than 0.001). Initial
cardiac index [U 4.97 +/- 0.831 X min-1 X m-2, N 4.44 +/- 0.62] and total
peripheral vascular resistance index [(TPRI) U 2,160 +/- 353 dyn X s X cm-5
X m-2, N 1,976 +/- 420] were slightly, but not significantly, higher in
uremic animals. Initial central venous pressure, wedge pressure, and plasma
norepinephrine level were greater in the uremic dogs. At the end point of
volume depletion, both uremic and nonuremic animals had achieved similar
levels of TPRI, despite greatly attenuated or absent increases in plasma
renin activity in the uremic group. At end point, blood volumes and plasma
norepinephrine levels were comparable. The increase in pulse rate was
higher in the uremic animals (59 +/- 37 pulses/min) compared with controls
(25 +/- 52, P less than 0.05). In an additional group of uremic dogs,
cardiovascular responses to hemorrhage and isolated ultrafiltration were
compared and found to be similar, after allowance for blood viscosity
changes had been made. The data suggest that in acutely uremic conscious
dogs, despite reduced renin-angiotensin responses, hemodynamic adaptation
to rapid volume depletion is not impaired.
