Thin polycarbonate membranes for use in hemodialysis

Claim 1

An improved membrane prepared by a wet phase inversion technique using an aqueous gelation system, said membrane composed of a 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 being adaptable for use in a hemodialysis apparatus to preferentially remove middle molecular weight molecules from blood, wherein said membrane has a diffusive permeability to sodium chloride of about 800 to 860 cm/min × 10 -4 , a diffusive permeability to vitamin B 12 of greater than 105 cm/min × 10 -4 , an ultrafiltration rate of less than 4.0 ml/hr/M 2 /mmHg, both the diffusive permeabilities and ultrafiltration rate measured at 37° C, and a thickness of from about 0.60 mil to about 0.95 mil.

Claim 10

A method of dialysing a patient comprising a. mounting a membrane in a hemodialyzer, b. connecting said hemodialyzer to a patient so that blood can be removed from the patient, passed through the hemodialyzer and returned to the patient in a closed loop, c. removing blood from a patient; d. 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 process; and 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 composed of a polyether-polycarbonate block copolymer having a molecular weight within the range of from about 200,000 to 500,000 as determined by intrinsic viscosity measurement, 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 800 to 860 cm/min × 10 -4 , a diffusive permeability to vitamin B 12 measured at 37° C of greater than 105 cm/min × 10 -4 , an ultrafiltration rate measured at 37° C less than 4.0 ml/hr/M 2 /mmHg and a thickness of from about 0.6 mil to about 0.95 mil.

Claim 11

A method of dialysing a patient comprising a. mounting a membrane in a hemodialyzer, b. connecting said hemodialyzer to a patient so that blood can be removed from the patient, passed through the hemodialyzer and returned to the patient in a closed loop, c. removing blood from a patient; d. 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 process; and 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 composed of a polyether-polycarbonate block copolymer having a molecular weight within the range of from about 200,000 to 500,000 as determined by intrinsic viscosity measurement, 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 800 to 860 cm/min × 10 -4 , a diffusive permeability to vitamin B 12 measured at 37° C of greater than 105 cm/min × 10 -4 , an ultrafiltration rate measured at 37° C less than 4.0 ml/hr/M 2 /mmHg and a thickness of from about 0.6 mil to about 0.95 mil.