Membrane distillation of human plasma ultrafiltrate and its theoretical applications to haemodialysis techniques

Membrane Distillation (MD) is a technique that allows the extraction of waf er from aqueous solutions. The basic principle is that vapour, but not liqu id water, can pass through hydrophobic micro-porous membranes, along a temp erature gradient, with consequent separation of water from solutes. In this study we evaluated the possibility to utilise MD to extract water from Pla sma Ultrafiltrate (PU) of patients with Chronic Renal Failure (CRF). The ex periments were carried out in vitro by a hydro-phobic polypropylene hollow- fibre distillation module; PU was obtained by a CRF patient utilising a hig h permeability polisulphone membrane. The results show that water can be ex tracted by MD from PU of CRF subjects at a constant rate and that none of t he substances analysed in PU was able to pass through the polypropilene mem brane. In the future MD could integrate extra-corporeal blood purification techniques allowing the re-utilisation of plasmatic water thus ameliorating the treatment of uraemia.