Evaluation of 99mTechnetium/51Chromium Post‐Transfusion Recovery of Red Cells Stored in Saline, Adenine, Glucose, Mannitol for 42 Days1

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Abstract
An in vivo and in vitro study of 42‐day saline, adenine, glucose, mannitol (SAGM) red cells (Terumo Corporation, Elkton, Md.) was conducted using 20 volunteers to document in vivo efficacy and analyze the validity of the 99mTc/51Cr technique. In vivo autologous post‐transfusion recovery was measured by a double‐label procedure involving the use of 99mTc‐labeled freshly drawn red cells to quantify recipient blood volume and 51Cr to document both posttransfusion 24‐hour recovery (PTR) and red cell survival. As an internal control, 5 of the 20 donors studied had red cell volumes estimated by the 125I‐albumin (RISA) plasma volume technique on a separate occasion. For comparison, PTR was also calculated according to the single‐label 51Cr protocol in which recipient blood volume was estimated by extrapolation from circulating 51Cr‐labeled red cell activity 5–15 min after infusion. After 42 days of storage, PTR averaged 78±6% with the double‐label 99mTc/51Cr technique and 81±5% with the single‐label (51Cr alone), confirming a small difference between the two techniques. Correlation between the two techniques was high, r = 0.81, though the average 3% difference between them was significant (p99mTc‐red cell method and the 125I‐albumin method exhibited excellent correlation, r = 0.96, and averaged 1,961 ±420 ml and 2,048±381 ml, respectively. Standard in vitro parameters of SAGM red cell concentrates were well preserved with hemolysis of 0.5±0.4% and red cell ATP 69±13% of the initial values after 42 days of storage. The double‐label, 99mTc/51Cr, post‐transfusion recoveries exhibited a slightly better correlation with post‐storage ATP when compared to single‐label, 51Cr, recoveries: r = 0.705 versus r = 0.644, respectively. The results confirmed acceptable 42‐day storage parameters for modified SAGM red cells.