MORPHOLOGICAL-CHANGES IN THE PERITONEAL VASCULATURE OF PATIENTS ON CAPD WITH ULTRAFILTRATION FAILURE

Vascular changes in the peritoneum were histochemically assessed in pa tients on continuous ambulatory peritoneal dialysis (CAPD) with ultraf iltration failure. Light microscopy showed extensive interstitial fibr osis, mesothelial denudation and vascular changes. Morphological chang es in the vasculature were observed at different levels. The specific changes in the vasculature in these patients were characterized by sev ere fibrosis and hyalinization of the media of venules. Immunofluoresc ence microscopy revealed extensive deposition of such extracellular ma trices as type IV collagen and laminin in the vascular wall. Electron microscopy revealed a significant increase in collagenous fibers and d egeneration of smooth muscle cells in the media. However, the endothel ial cells at the levels of vasculature affected were relatively well p reserved. These pathological alterations in the vasculature in CAPD pa tients with ultrafiltration failure suggest that certain toxic factors , such as a high osmolar dialysate or low pH of dialysate, had affecte d the peritoneal vasculature from the adventitial side rather than the endothelial side. These vascular changes in the peritoneum are though t to be irreversible, associated with deterioration of peritoneal func tion, and to cause ultrafiltration failure in the patients on longterm CAPD therapy.