Reduction of Otherwise Intractable Edema by Dialysis or Filtration
THIS article is concerned only with the removal of edema that either has been resistant to the usual forms of treatment, or is of such a nature that the latter are contraindicated for the patient. When salt-free diet, sodium-binding resins, digitalis, or mercury preparations fail, or cannot be used, artificial kidneys or other dialyzing methods may be useful; they have the additional advantage that during dehydration, retention products are also removed. (For details of technics see references 1 and 2.)
Dialysis With Hypertonic Solutions to Remove Edema
Most artificial kidneys use dialysis, which means purification through a semipermeable membrane, with the patient’s blood on one side of a cellophane membrane and rinsing fluid on the other side.1–4 In peritoneal lavage, dialysis occurs through the peritoneum and walls of the numerous capillaries in the subserosa. Electrolytes will equilibrate on both sides of the membrane; urea and other retention products are removed from the blood by the dialysis. Five to eight hours of treatment will suffice to reduce the patient’s blood urea from very high levels to nearly normal values with efficient artificial kidneys.
In the artificial kidneys that use dialysis only, there is no difference in hydrostatic pressure between the patient’s blood in the cellophane tubing and the rinsing fluid. Under these circumstances, while urea is moving across the cellophane from the blood to the rinsing fluid (fig. 1), water is being attracted to the uremic blood, as it will always pass from a place of lower concentration of solutes . . .