The Freezing of Human Serum and Plasma in Medical Research Council Transfusion Bottles, Before Drying by Sublimation from the Frozen State

Abstract

Human serum was dried in this department at the outbreak of war with a view to its possible use as a stable substitute for whole blood for transfusion purposes. In the absence of any definite knowledge of dosage, the arbitrary unit of 200 c. c. was chosen, because this was approximately the amount of serum which could be obtained from a pint of clotted blood, and also because this amount of serum could conveniently be frozen before drying in 12 oz. medical-flat bottles. The technique of freezing was to place the bottles of serum on racks in a cold-room maintained at –20° C, the racks being slightly inclined from the horizontal so that the serum froze in a wedge, thus giving a reasonably large surface from which evaporation could occur during the drying process. Large amounts of human serum have been dried by sublimation from the frozen state on apparatus based on the experimental model described by Greaves & Adair (1939), after prefreezing by this simple technique.