Toxemia of pregnancy and altered renal circulation

1. A theory is advanced that “toxemia of pregnancy” is a “postural disease”. It is unknown in quadrupeds and appears infrequently among primitive people who normally spend much of their time in a semiquadruped position. The mechanism would appear to be that in the erect position, the forces of gravity on the abdominal and pelvic organs being reversed, the gravid uterus may give increased intra-abdominal pressure, direct pressure on the kidneys, compression of renal vessels, and pressure on the lower urinary tract. The result of these forces individually or in combination would tend to cause altered renal circulation.2. Experimental evidence has demonstrated that altered renal circulation if present can cause:A. Hypertension, by a humoral mechanism.B. Proteinuria, which is known to appear with renal circulatory change.C. Edema, which is the clinical result of salt and water retention.This triad appearing in a pregnant woman is toxemia.In the primary phase these symptoms represent only the functional response of the body to mechanical interference with renal circulation. They may be present without impairment of renal function or demonstrable change in renal blood flow.3. With more severe interference with renal circulation these primary symptoms may progress to include:A. Severe hypertension, coma, and convulsions.B. Oliguria with azotemia which may go on to anuria and uremia.C. Generalized edema with its added effect on kidneys and brain.D. Hypertensive vascular changes with hemorrhages and necrosis, including histologic changes in the kidneys and liver which are sometimes found at autopsy in fatal cases.4. Treatment should be directed toward the improvement of the renal circulation, that is, the removal of the external and internal renal tamponade. Postural exercises may be of some value. Limited salt intake will tend to reduce the compression caused by interstitial renal edema. Peripheral vasodilating drugs or procedures may be temporarily beneficial, but real improvement can be anticipated only when the uterus is emptied and unimpaired circulation is re-established to the renal parenchyma.5. Quadruped locomotion, the logical prophylaxis, appears impractical.