Method of storing red blood cells which minimizes both red blood cell hemolysis and exposure to blood extractable plasticizers

Claim 1

A method of storing a quantity of red blood cells at 4° C., said method comprising the steps of fabricating a polyvinyl chloride material having a desired degree of flexibility by using a combination of first and second plasticizers, the first plasticizer being present in an amount of from 5 to 30 percent by weight of the material and consisting of a fatty ester containing at least three ester linkages comprising fatty hydrocarbon groups of at least four carbon atoms on a hydrocarbon chain, the second plasticizer being present in an amount of from 10 to 25 percent by weight of the material and being selected from the group consisting of fatty esters containing at least two ester linkages comprising fatty hydrocarbon groups of 4 to 12 carbon atoms each on a hydrocarbon chain and phosphate esters containing at least two ester linkages comprising fatty hydrocarbon groups of 4 to 12 carbon atoms, forming a bag from the flexible material, conveying the quantity of red blood cells into the bag, and storing the quantity of red blood cells within the bag at 4° C. for the desired storage interval, and permitting the plasticizers to leach from the bag material into the quantity of red blood cells during the storage interval, the second plasticizer, upon leaching, being capable of suppressing the formation of plasma hemoglobin within the red blood cells, the plasticizers being present, in combination, within the quantity of red blood cells in amounts which, at the end of the storage interval, are significantly less than had the second plasticizer been used alone in greater weight percentages to achieve the desired degree of flexibility for the bag material but which, dut to the leaching of the second plasticizer, albeit in lesser amounts, are still sufficient to suppress the amount of plasma hemoglobin in the red blood cells.

Claim 2

A method of storing a quantity of red blood cells at 4° C., said method comprising the steps of fabricating a polyvinyl chloride material having a desired degree of flexibility by using a combination of first and second plasticizers, the first plasticizer being present in an amount of from 5 to 30 percent by weight of the material and consisting of a fatty ester containing at least three ester linkages comprising fatty hydrocarbon groups of at least four carbon atoms on a hydrocarbon chain, the second plasticizer being present in an amount of from 10 to 25 percent by weight of the material and being selected from the group consisting of fatty esters containing at least two ester linkages comprising fatty hydrocarbon groups of 4 to 12 carbon atoms each on a hydrocarbon chain and phosphate esters containing at least two ester linkages comprising fatty hydrocarbon groups of 4 to 12 carbon atoms, forming a bag from the flexible material, conveying the quantity of red blood cells into the bag, and storing the quantity of red blood cells within the bag at 4° C. for the desired storage interval, and permitting the plasticizers to leach from the bag material into the quantity of red blood cells during the storage interval, the second plasticizer, upon leaching, being capable of suppressing the formation of plasma hemoglobin within the red blood cells, the plasticizers being present, in combination, within the quantity of red blood cells in amounts which, at the end of the storage interval, are significantly less than had the second plasticizer been used alone in greater weight percentages to achieve the desired degree of flexibility for the bag material but which, dut to the leaching of the second plasticizer, albeit in lesser amounts, are still sufficient to suppress the amount of plasma hemoglobin in the red blood cells.