Hemodialysis therapy

Engineering Aspects of Hemodialysis. Engineering interest in hemodialysis is concentrated on the optimization of the hemodialysis membrane (4,41), the dependency of solute removal on membrane and device characteristics (14,15), and quantitation of hemodialysis therapy through urea pharmacokinetics (42—44). 

He was hospitalized for revision of his arteriovenous shunt and postoperatively complained of symptoms of gastroesophageal reflux. This complaint prompted institution of cimetidine therapy. In view of the patient s impaired renal function, the usually prescribed dose was reduced by half. Three days later, the patient was noted to be confused. An initial diagnosis of dialysis dementia was made and the family was informed that dialysis would be discontinued. On teaching rounds, the suggestion was made that cimetidine be discontinued. Two days later the patient was alert and was discharged from the hospital to resume outpatient hemodialysis therapy. 

Hemolysis was reported after hemodialysis therapy with a dialysis fluid inadvertently contaminated with hydrogen peroxide (3). 

Gotch F. Urea kinetics modelling to guide hemodialysis therapy in adults. In Nissenson AR, Fine RN, eds. Dialysis therapy. Philadelphia Hanley and Belfus, 2002 117-21. 

A deficiency in delivered hemodialysis therapy may be related to patient compliance with the dialysis prescription (ending dialysis early). Other causes for a low Kt/V include low blood flow rates due to access stenosis or thrombosis, or due to the use of catheters. Adequate dialysis may not be achieved in some patients despite compliance and sufficient blood flow. Eor these patients there are really only two options to increase urea clearance use a larger membrane or increase the treatment time. 

Tsukamoto Y, Saka S, Kumano K, Iwanami S, IsHiDA O and Marumo F (1990) Abnormal accumulation of vanadium in patients on chronic hemodialysis therapy. Nephron 56 368—373. 

For an attempt to actually evaluate patient utilities in a clinical setting, the reader might be interested in Bass et al. (2004). The authors surveyed, 109 patients on hemodialysis therapy, 5 7 patients on continuous ambulatory peritoneal dialysis (CAPD), and 22 patients on continuous cycling peritoneal dialysis (CCPD) (p. 695). They found that whereas many patients would be prepared to increase their dose to increase survival chances, few would be prepared to change the modality of treatment. 

Immunologic A leukocytoclastic vasculitis has been attributed to cinacalcet in an 80-year-old woman on maintenance hemodialysis therapy [44" ]. After taking cinacalcet for 3 days she developed palpable purpura on all four limbs, which resolved after withdrawal of cinacalcet and administration of glucocorticoids. 

It is important to identify patients who may eventually require renal replacement therapy since adequate preparation can decrease morbidity and perhaps mortality. Early identification enables dialysis to be initiated at the optimal time with a functioning chronic access. The placement and adequate maturation of arteriovenous fistula (AVF) before the initiation of hemodialysis therapy requires timely patient education and counselling, selection of the preferred renal replacement modality, selection of an access type and location, and creation of the access at least several weeks to months in advance of its expected need. An early constructed AV fistula could also have a beneficial effect on the rapidity of worsening kidney failure. Reasons for this could be increased heart preload and consequently increased afterload or decreased peripheral resistance with increased renal perfusion. A simpler reason could be that patients after AV fistula construction become aware that situation is serious and they start to follow the therapy more accurately [11]. 

A well-functioning VA is mandatory for the adequate hemodialysis therapy. As compared to catheter-based approach, AVF creation is associated the lowest rate of complications [32], and a vast majority of the patients tolerate it very well. 

The selection of the polymer material for the production of dialysis membranes has significant implications on the quality of hemodialysis therapy. Only a limited number of polymers are suitable for the spinning and extrusion process involved in the manufacture of capillary membranes. The selection was originally based on experiences from textile fiber production. Further, biochemical and physical properties that may result from the membrane formation process, determine the selection of a polymer. The ideal polymer family should allow the production of biocompatible dialysis membranes and possess a stable physical stability. The latter guarantees an easy production process and sterilization without problems. 

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