Relatively thick polycarbonate membranes for use in hemodialysis

Claim 1

A membrane of a hydrophilic polycarbonate copolymer consisting of 5 to 35% by weight of repeating alkylene ether carbonate units and from 95 to about 65% by weight of repeating bisphenol A-carbonate units, said copolymer having a molecular weight within the range of from 200,000 to about 750,000 as determined by intrinsic viscosity measurement, said membrane having a thickness of 0.00098 to about 0.00145 inches and having the properties when used in a hemodialysis apparatus of preferentially removing middle molecule weight molecules from blood, said membrane having a diffusive permeability measured at 37° C. to sodium chloride of about 630 to 750 cm/min×10 -4 , a permeability to urea of about 665 to 815 cm/min×10 -4 , a permeability to vitamin B 12 of about 90 to 110 cm/min×10 -4 and an ultrafiltration rate of about 2.9 to 5.5 ml/hr/M 2 /mm Hg.

Claim 13

A method of dialysing a patient comprising in a closed loop (a) removing blood from a patient (b) passing said blood through a hemodialyzer wherein the blood is brought into contact with one face of a membrane mounted within said hemodialyzer while a dialysis liquid is simultaneously circulated through the hemodialyzer in contact with the opposite face of the membrane mounted in the hemodialyzer, the flow rates of the blood and dialysis liquid corresponding to the normal conditions of a hemodialysis operation, and (c) returning the dialyzed blood to the patient the improvement being the use in the hemodialyzer of a membrane prepared by a wet phase inversion technique using an aqueous gelation system, said membrane being composed of a polyetherpolycarbonate block copolymer having a molecular weight within the range of from about 200,000 to 750,000 as determined by intrinsic viscosity measurement, said polyether-polycarbonate block copolymer containing 5 to 35% by weight of repeating alkylene ether carbonate units and from 95 to about 65% by weight of repeating bisphenol A-carbonate units, said membrane having a diffusive permeability, measured at 37° C., to sodium chloride of about 630 to 750 cm/min×10 -4 , a permeability to urea of about 665 to 815 cm/min×10 -4 , a diffusive permeability to vitamin B 12 , measured at 37° C., of about 90 to 110 cm/min×10 -4 an ultrafiltration rate, measured at 37° C., of about 2.9 to 5.5 ml/hr/M 2 /mmHg and a thickness greater than 0.00098 inches.

Claim 14

A method of dialysing a patient comprising in a closed loop (a) removing blood from a patient (b) passing said blood through a hemodialyzer wherein the blood is brought into contact with one face of a membrane mounted within said hemodialyzer while a dialysis liquid is simultaneously circulated through the hemodialyzer in contact with the opposite face of the membrane mounted in the hemodialyzer, the flow rates of the blood and dialysis liquid corresponding to the normal conditions of a hemodialysis operation, and (c) returning the dialyzed blood to the patient the improvement being the use in the hemodialyzer of a membrane prepared by a wet phase inversion technique using an aqueous gelation system, said membrane being composed of a polyetherpolycarbonate block copolymer having a molecular weight within the range of from about 200,000 to 750,000 as determined by intrinsic viscosity measurement, said polyether-polycarbonate block copolymer containing 5 to 35% by weight of repeating alkylene ether carbonate units and from 95 to about 65% by weight of repeating bisphenol A-carbonate units, said membrane having a diffusive permeability, measured at 37° C., to sodium chloride of about 630 to 750 cm/min×10 -4 , a permeability to urea of about 665 to 815 cm/min×10 -4 , a diffusive permeability to vitamin B 12 , measured at 37° C., of about 90 to 110 cm/min×10 -4 an ultrafiltration rate, measured at 37° C., of about 2.9 to 5.5 ml/hr/M 2 /mmHg and a thickness greater than 0.00098 inches.