Renal Function, Sodium, Volume, and Arterial Pressure Relationships
Nephrologists have a greater awareness of the important relationships between the kidneys and the cardiovascular system than any other group of clinicians. This association between renal function and the cardiovascular system was recognized by Richard Bright nearly a century ago. It was logical for investigators in the early twentieth century to assume that if the kidneys were unable to excrete sodium and water at a rate equivalent to daily intake, blood volume would expand with a resultant rise of cardiac output and arterial pressure. Curiously, however, as technology progressed through the 1930s to the present time, this basic notion became increasingly difficult to accept. It was found that even with decreased excretory ability of the kidneys and associated hypertension, blood volume and cardiac output could be either normal, low, or elevated.(1,2) The extracellular fluid volume was found to be inversely related to the level of arterial pressure in patients with essential hypertension. Elevation of peripheral vascular resistance appeared to be the only hemodynamic variable that hypertensive patients had in common, even those with clear evidence of decreased renal excretory capacity.
KeywordsCardiac Output Arterial Pressure Fluid Volume Sodium Intake Total Peripheral Resistance
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