Portable/wearable artificial kidney (WAK) - initial evaluation.

This report discusses the modus operandi and results achieved using this new mode of haemodialysis. An insulated 20 L dialysate bath acts as a carrying case for the system. When empty the case is large enough to hold the wearable module and complete supplies for one week's operation. The total weight is 17 kg. The wearable unit consists of a combined blood and dialysate pump (1.2 kg), rechargeable batteries, tubing, Dow dialyser and charcoal regeneration module with a total weight of 3.5kg. Ideally the patient dialyses using a single needle some 3 hours/day, 6 days/week. It is necessary for the wearable module to be connected to the 20 L dialysate bath for an average of 90 minutes to achieve adequate urea and 5+ removal. One patient was dialysed on 35 consecutive days and 4 others were dialysed intermittently. Routine laboratory tests and mass balance studies were performed on all patients. Ultrafiltration rates reached 700 ml/hour, routine serum chemistries remained stable and mass balance studies demonstrated a daily removal of urea 14-20 G, creatinine 1500-2000 mg, uric acid 500-900 mg and K+ 30-55 mEq. It is concluded that dialy dialysis with WAK is biochemically adequate and also permits the patient a much less restricted esistence.