PREDILUTION HEMOFILTRATION - CLINICAL-EXPERIENCE AND REMOVAL OF SMALLMOLECULAR-WEIGHT SOLUTES

Over 1500 treatments of hemofiltration with on-line preparation of sub stitution fluid were performed in 16 patients. Two patients were treat ed for over 40 months. On-line preparation of the solution allowed use of bicarbonate as a buffer. 73-74 L/session were infused in pre-dilut ion modality, at a rate of about 370 ml/min, and the treatment length was above 4 hrs. The good quality of on-line prepared solution was con firmed by the negativity of microbiological tests and by the absence o f clinical or sub-clinical reactions in patients. Urea clearance was c alculated by equations considering either plasma flow or whole blood f low. Results were 196-197 ml/min and 186-183 ml/min, respectively. The latter was nearer to the value of directly measured clearance (182-17 3 ml/min). Kt/V urea was about 1 per session and PCR ranged between 1. 3 and 1.4 g/kg/day. A high Vascular stability was also observed. Since sodium balance may, at least in part, account for better vascular sta bility, sodium sieving coefficient was measured during the treatment. The sodium-retaining effect of the increase of protein concentration w ithin the filter, due to the ultrafiltration, was less relevant in pre -dilution hemofiltration if compared to post-dilution hemofiltration. It has been calculated that to obtain a sodium balance similar to that of the hemodialysis (HD), the sodium concentration of infusion soluti on should be about 2 mEq/L higher than HD dialysis solution. However, difficulty in performing accurate balance studies prevents a general a greement on these conclusions.