Hepatitis B vaccination in dialysis patients and nutritional status.

35 dialysis patients underwent anti-HBV vaccination. We classified patients in responders or non-responders using an anti-HBs titer of 50 UI/l as the discriminating serum level and tried to assess whether the antibody response bears any relationship with the nutritional status. 26 patients (74%) reached the target atb titer, which was maintained during follow-up (average 360 UI/l). The weak response in the other 9, with values never exceeding 20 UI/l, was short-lived. Anthropometric and impedenziometric parameters were higher in responders than in nonresponders, but the difference did not reach statistical significance. We conclude that the atb titer which discriminates uremics in responders or not must be greater than 50 UI/l and that the nutritional status may interfere with the seroconversion rate, but this conclusion needs to be validated in a wider population.

Influence of blood temperature on vascular stability during hemodialysis and isolated ultrafiltration.

We tested the hypothesis that differing temperature (T) changes in extracorporeal blood circuit might partly account for the difference in vascular stability (VS) between isolated ultrafiltration (UF) and simultaneous UF-hemodialysis (HD). The study was carried out in 6 patients who presented frequent episodes of symptomatic hypotension during the routine dialytic sessions. During simultaneous UF-HD with dialysate T set at 37.5 degrees C (standard HD), blood reentered the patients with a T of about 2 degrees C higher, whereas during isolated UF (standard UF) 2 degrees C lower, than at its exit. These extracorporeal blood T changes were reciprocated by warming the venous line in isolated UF (warm UF) and by setting the dialysate at 34.5 degrees C in simultaneous UF-HD (cold HD). During warm UF mean arterial pressure (MAP) fell and heart rate (HR) increased nearly as much as during standard HD. Vice versa, during cold HD MAP and HR remained nearly as stable as during standard UF. It is concluded that the T changes in blood flowing through the extracorporeal circuit largely account for the differing VS between isolated UF and simultaneous UF-HD.

Blood temperature and cardiovascular stability in hemofiltration.

Temperature (T) changes in the blood flowing through the extracorporeal circuit markedly affect cardiovascular tolerance to fluid removal during either hemodialysis (HD) and isolated ultrafiltration. In this study we investigated the effect of blood T changes during postdilutional hemofiltration (HF). To this purpose we compared the changes in mean arterial pressure (MAP) and heart rate (HR) during HF and HD carried out at equivalent T of blood in the venous segment of the extracorporeal circuit. Results show that HF entails some heat loss from blood flowing in the extracorporeal circuit; if heat loss is made similar, HD affords nearly as much blood pressure protection as HF does. On the other hand at equivalent heat gain, HF causes nearly as much hypotension as HD does. We conclude that blood T changes in the extracorporeal circuit affect vascular stability (VS) even in HF. The marginal benefit of HF over HD, still observed at equalized T changes, remains to be elucidated.

Bone oxalosis and renal osteodystrophy.

Bone biopsy specimens from four patients with hyperoxaluria who underwent hemodialysis were studied. Calcium oxalate crystals are laid down in marrow spaces and sometimes inside the bone matrix and uncalcified osteoid tissue. They are clearly visible by polarizing microscope and are stained grayish-brown by Pizzolato's method. Most are surrounded by basophilic, amorphous material. By electron microscope they appear as elongated, empty spaces and after hydrogen peroxide treatment appear as fragmented, slightly electron-dense, needle-like structures. In marrow spaces, oxalate crystals aggregate in round clusters surrounded by a granulomatous reaction. This, however, cannot remove the oxalate crystals. Bone histology shows advanced renal osteodystrophy, ie, severe osteomalacia and hyperparathyroidism. The granulomatous reaction induced by the oxalate crystals probably contributes to and worsens the changes from hyperparathyroidism.