Estimation of Blood Volume From Change in Blood Specific Gravity Following a Plasma Infusion 12

In the treatment of wounded men in shock, the rapid intravenous infusion of plasma is almost a routine preliminary to prevent further deterioration of the clinical condition of the pa-tient, while the extent of injuries and the clinical condition are evaluated. If one can add to this evaluation a quick approximation of the blood volume obtained by estimating the dilution caused by the infused plasma, one will have information of value in deciding further therapy. This paper presents data which indicate that the blood volume can be estimated, within:1 15 per cent, from the decrease in blood specific gravity caused by infusion of a known volume of isosmotic plasma or albumin solution. The specific gravity determinations on the 3 samples, blood drawn before the infusion, blood drawn 5 to 10 minutes after the infusion, and infused plasma or albumin, can be quickly and accurately determined by the copper sulfate method (1). About 2 minutes suffice for the specific gravity determinations and the calculation of blood vol-ume from the appended line chart. This method of estimating blood volume will be called Procedure A. An alternative procedure, B, is to estimate blood volume from the decrease in hemoglobin concentration caused by infusion of a known volume of isosmotic plasma or albumin solution. lThese studies were supported in part by a contract, recommended by the Committee on Medical Research,