Acid-base balance and oxygen tension during dialysis in uremic patients with chronic obstructive pulmonary disease

Recent reports on the effects of dialysis on acid-base balance and metabolic acidosis correction in end-stage renal disease (ESRD) patients with chronic obstructive pulmonary disease (COPD) are lacking. Here, we compared acid-base balance and blood gasses among 14 patients with established COPD (group A) and eight patients with normal respiratory function (group B). The two groups were homogeneous for age, time on dialysis, and male/female ratio. At the beginning of dialysis, acid-base balance and blood gasses were comparable between patients of groups A and B. A significant difference between groups was observed only in pCO(2) at 20 min, together with a delay in pH increase. Effective correction of acidosis was reported at the end of dialysis and is not significantly affected by COPD. Nevertheless, weight loss must be carefully monitored in these patients in order to prevent hyperhydration and worsening of respiratory function

Medial artery calcification of uremic patients: a histological, histochemical and ultrastructural study

Recent findings suggest that vascular calcification (VC) is an active process similar to bone mineralization, the vascular smooth muscle cells (VSMCs) undergoing phenotypic differentiation into osteoblastic cells and synthesizing calcificationregulating proteins found in bone. This study has investigated the VC process of uremic patients, with a morphologic approach. Epigastric artery samples from 49 uremic, non-diabetic patients were taken during kidney transplantation. Sections from paraffin-embedded samples were stained with hematoxylin/eosin and von Kossa. CD68 was immunohistochemically detected, and sections from frozen samples were stained with Oil Red O. Deeply calcified samples were stained with Picrosirius Red, PAS, and Alcian blue. Specimens from one patient with moderate and one with severe VC were examined under the electron microscope. None of the samples had atherosclerosis. Calcifications were found in the media of 38 patients. In 23, dot-like calcifications were irregularly scattered near the adventitia (light VC); in 11, granular calcifications formed concentric rings near the adventitia (moderate-advanced VC); in 4, zones of consolidated calcifications were found (severe VC). These zones were poor in collagen, glycoproteins and proteoglycans. In cases with moderate or severe VC, VSCMs showed necrotic changes. Matrix vesicles could be recognized in the extracellular spaces. In cases with severe VC, uncalcified or partially calcified membranous bodies were found, together with Liesegang rings. Patches of fibrin were also found. These findings point to a mainly degenerative mechanism of VC, which proceeds from the outer portion of the media. An active mechanism, however, cannot be excluded. A unifying hypothesis is suggested