Varying methods of sterilisation, and their effects on the structure and permeability of dialysis membranes

This study elucidates changes in membrane structure and permeability due to the methods of sterilisation and the conditions under which they are carried out. Tubular dialysis membranes of regenerated cellulose having various values for porosity were sterilised by ethylene oxide gas, autoclave or gamma irradiation under varying conditions. Non-sterilised membranes were included as controls. The solute permeability of the membranes was determined using 14C-urea. The membranes tested showed no difference in clearance of urea or creatinine. Gamma-ray sterilisation under dry conditions greatly reduced the vitamin B12 clearance and hydraulic permeability of membranes with a water content of below 60%. Hydraulic permeability increased with gamma irradiation for membranes sterilised under wet conditions. A reduction in vitamin B12 clearance for membranes with a water content of above 60% resulted after autoclave sterilisation. Pore model calculation reveals that membrane shrinkage resulted from sterilisation both by gamma-rays under dry conditions, and by autoclave. Thus, the structure of dialysis membranes varies with the method of sterilisation and the conditions under which the sterilisation is carried out.