Automated peritoneal dialysis with 'on-line'-prepared bicarbonate-buffered dialysate: technique and first clinical experiences

Background. Automated peritoneal dialysis (APD) has the possibility of increasing the dialysis efficacy by using higher fill volumes, frequent dialysate exchanges, and tidal techniques. It is then possible to treat patients adequately without residual renal function. The drawbacks of the required high amounts of dialysis solution of up to 30 litres per session are the high costs of lactate-based dialysate bags and difficulties for the patients in handling these bags. So far, bicarbonate-based peritoneal dialysate, which may be more biocompatible, is only available for CAPD in double-chamber bags. In APD this could be overcome by 'on-line' preparation of bicarbonate-buffered dialysate using advanced technologies originally designed for on-line preparation of substitution fluid for haemofiltration. Methods. Four patients without residual renal function were treated with APD five times weekly in a crossover study design. Patients received standard lactate-based (35 mmol/l) treatment (25 litres per session each) in weeks 1 and 3. In week 2 on-line-produced bicarbonate-buffered (37 mmol/l) dialysate was used. This dialysate was prepared by an AK 100 Ultra haemodialysis machine. The machine was modified for adding glucose from a 50% concentrate to the desired concentration of 1.7%. Electrolytes, pH, pCO2, and dialysis efficacy parameters were measured. Micro-biological testing was carefully performed. Results. Creatinine clearances, Kt/V, and pCO2 did not vary between the different treatment phases, whereas the pH showed a distinct increase during the bicarbonate phase. Repeated determinations of endotoxins and culturing showed no contamination of the dialysate. The composition of the produced dialysate was reproducible with respect to pH, pCO2, sodium, calcium and bicarbonate, whereas the glucose concentration varied by ±20%. Conclusions. On-line preparation of PD fluid with the AK 100 Ultra is easy and safe to handle. APD with dialysate containing 37 mmol/l bicarbonate provides improved acid-base balance and possibly improved biocompatibility, and may lead to a significant cost reduction. Further development in order to provide smaller machines and more precise ways of achieving a desired dialysate glucose concentration is necessary.     

Effects of bile acid and salicylate on isolated surface and glandular cells of rabbit stomach

Little is known about the response of surface cells and glandular cells of the gastric mucosa to various injurious agents. This study examines the effects of bile acid and salicylate on oxygen consumption and membraneolysis of isolated gastric mucosal surface cells and compares these responses to those of cells constituting the gastric glands. The effects of salicylate and bile acid on oxygen consumption by surface cells are similar to previous observations for intact gastric glands and isolated mitochondria, indicating alterations of oxidative phosphorylation. Salicylate does not appreciably alter lipid release from either surface or glandular cells. However, bile acid causes a profound increase in lipid release from both surface and glandular cells. Salicylate does not alter the number of visibly intact surface or glandular cells, but 1 mM of taurocholic acid decreases the number of surface cells by 45% without altering the glandular cells. In contrast, 5 mM of taurocholic acid completely destroys the surface cells and reduces the number of gastric glandular cells by 51%. These data suggest that surface cells are more susceptible to membraneolytic effects of bile acid than are gastric glandular cells. This may account for the superficial nature of bile acid-induced injury to the gastric mucosa. Although both bile acid and salicylate interfere with oxidative metabolism, this effect alone does not appear to account for cellular destruction.     

Failure of ablation of a mediastinal parathyroid adenoma by repeated contrast staining

In a patient with primary hyperparathyroidism an attempt was made to ablate a middle mediastinal parathyroid gland by forceful staining with radiographic contrast material. The gland was stained on two separate occasions, two weeks apart. Both times the serum calcium level temporarily fell to the normal range but reverted to abnormal levels. The patient ultimately required surgery for correction of hypercalcemia. The mechanism of staining and possible reasons for failure as well as potential complications are discussed.     

Dynamic computed tomography of the head and neck: differential diagnostic value

A retrospective review of the dynamic CT studies performed in our institution on head and neck lesions, excluding the brain, was carried out. Five basic types of density vs. time curves were obtained. Dynamic CT scanning is valuable in the differential diagnosis, management, and followup of such cases; its usefulness as an imaging modality in diagnosis and followup of hemangiomas is stressed.