(HealthDay News) – Red blood cells stored longer than three weeks begin to lose their flexibility, according to a small study published online Feb. 28 in Anesthesia & Analgesia.

Steven M. Frank, MD, from Johns Hopkins University in Baltimore, and colleagues examined erythrocyte deformability in 16 posterior spinal fusion surgery patients, comparing those who required moderate transfusion (≥5 units erythrocytes) and those who received minimal transfusion (0–4 units erythrocytes). Samples were drawn directly from the blood storage bags before transfusion and from patients before and after transfusion (over three postoperative days). The elongation index measured using ektacytometry quantitatively assessed deformity.

The researchers found that erythrocyte deformability was significantly decreased compared to preoperative baseline in patients receiving moderate transfusion, but not after minimal transfusion. Over three postoperative days, these changes remained consistent. In erythrocytes stored for ≤21 days, deformability was significantly less than in those stored for >21 days or those drawn from patients preoperatively. Intermediate deformability was seen in cell-salvaged erythrocytes, which was greater than that of erythrocytes stored ≥21 days but less than that of erythrocytes stored <21 days.

“The findings demonstrate that increased duration of erythrocyte storage is associated with decreased cell membrane deformability and that these changes are not readily reversible after transfusion,” the authors write.

One author disclosed financial ties to Terumo BCT and Fenwal Labs, both involved with blood storage.

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