Hemodiafiltration in two chambers without replacement fluid: a clinical study

Paired filtration dialysis (PFD) is the only hemodiafiltration (HDF) technique in which ultrafiltrate (Uf) is obtained continuously with a similar composition to plasma. It has been proved that Uf is regenerated when it passes through an uncoated adsorbent charcoal cartridge: this one removes medium-to-large solutes and small toxines (except for urea and phosphates), but not the electrolytes and bicarbonate. This regenerated Uf can be used like replacement fluid, using the same Uf pump as the infusion pump; this makes the HDF technique easier and more reliable. During 12 months (3 h/3 sessions/week), we treated 13 patients with this PFD-Charcoal technique. These patients were previously on conventional PFD for at least 6 months. The biochemical results were excellent with a stabilization of all parameters (urea, creatinine, uric acid, Na, K, Cl, Ca, phosphates, beta 2-microglobulin, beta 2M, etc.) and a better control of acidosis (statistically significative after 6 months). The clinical tolerance was also excellent, and the technique was greatly simplified. We conclude that PFD-Charcoal is a good HDF technique that avoids the use of exogenous replacement fluid by using the regenerated Uf itself as an endogenous substitution fluid with bicarbonate.