James J. Cole

Dialysate made from dry chemicals using citric acid increases dialysis dose

A new dry dialysate concentrate acidified with citric acid (citrate dialysate) has been used in two separate clinical studies of hemodialysis patients. The first compared a single treatment using this dialysate, with one dialysis using regular standard dialysate acidified with acetic acid (regular dialysate) in a prospective, randomized, crossover study of 74 dialyses. Changes in blood levels of electrolytes and other blood constituents during dialysis were calculated by subtracting postdialysis from predialysis blood concentrations. Compared with acetic acid dialysate, citrate dialysate was associated with significantly greater decreases in total and ionized calcium, magnesium, and chloride levels. Citrate dialysate was also associated with greater increases in serum sodium and citrate concentrations, although their postdialysis concentrations remained within or just outside normal ranges. Changes in other blood constituents were similar with both dialysates. The second study used citrate dialysate exclusively for all dialyses over a 12-week period in 25 patients. Predialysis blood samples were drawn at the start of the study and at 4-week intervals thereafter, and postdialysis blood samples were obtained after the first and last dialysis. Repeated-measure analysis showed that although predialysis blood concentrations of magnesium, potassium, and citrate remained within the normal range, there was a significant declining trend over the course of the study. At the same time, predialysis serum bicarbonate levels increased, and significantly more patients had a predialysis bicarbonate concentration within the normal range at the end of the study than at the start (15 versus 8 patients; P = 0.001, chi-square). In 19 patients (excluding 3 patients for whom the type of dialyzer was changed during the study), the dose of dialysis for the first and last dialysis was calculated by urea reduction ratio and Kt/V. There was a significant increase in both measurements without changes in dialysis time, blood and dialysate flows, or dialyzer used. The urea reduction ratio increased from 68% +/- 5.9% to 73% +/- 5.3% (P < 0. 03), and the Kt/V from 1.23 +/- 0.19 to 1.34 +/- 0.20 (P = 0.01) from the first to last dialysis, respectively. In conclusion, this citric acid dialysate was well tolerated, and intradialytic changes in blood chemistries were similar to those seen with regular dialysate. Using dialysate containing citric instead of acetic acid increases the delivered dialysis dose.

Evolution of the Technique of Home Parenteral Nutrition

Experience with use of the artificial kidney in the home led to the concept of self-infusion of parenteral nutrients at home. Originally called an artificial gut, the term has been changed to home parenteral nutrition. The original method proposed for circulatory access, a side-arm on an A-V shunt, failed and forced the development of a right atrial catheter which proved to be both safe and longlasting. A safe and rapid self-mix system of nutrient preparation was developed which made the patient independent of the hospital pharmacy. A wearable infusion device proved workable but was abandoned because it was unnecessary and greatly interfered with patient rehabilitation. A portable infusion system has been developed which facilitates patient mobility during infusions as well as patient travel.

Clinical use of a totally heparin grafted hemodialysis system in uremic patients.

1. A totally heparin grafted dialysis system shows great promise in the treatment of chronic uremia associated with bleeding risk. 2. Long-term treatment of chronic uremia with this system has to await: a) Further studies of the chronic toxicity of CPC. b) Evaluation of performance which may be achieved by using a more homogeneous heparin with higher bioactivity. 3. Detailed studies of platelet factor 4 release with subsequent heparin neutralization to determine the importance of this variable in its effect on system performance.

An Animal Model for Fungal Peritonitis: Evaluation of Therapeutic Options

An animal model for fungal peritonitis was developed and is described. This model was used to compare various therapeutic options for Candida albicans peritonitis. Twenty-four rabbits were treated on three different protocols. Results from these protocols confirm the clinical observation that removal of the catheter is necessary for successful treatment of fungal peritonitis. Further, the combination of catheter replacement and imidazole anti-fungal therapy appears to be curative in this animal model, and suggests that by using this protocol, discontinuation of peritoneal dialysis may not be necessary.