The effect of red blood cell transfusion on the microcirculation of anemic children

Red blood cell transfusion can improve but also might temporarily reduce the microcirculation. The buccal microcirculation was visualized and total vessel density (TVD) determined with sidestream dark field imaging in 19 pediatric anemic (Hb 7.2 g/dL, 95 % CI 6.5-7.9) oncology or hematology patients receiving red blood cell transfusions (Tx) and in 18 age-matched healthy non-anemic controls. After transfusion, Hb (8.0 g/dL, 95 % CI 7.3-8.6) and TVD increased (14.7 ± 1.7 versus 16.6 ± 2.0 mm/mm(2)) significantly with a concomitant decrease in RBC velocity in medium-sized vessels (pre-Tx 711 ± 199 versus post-Tx 627 ± 163 μm/s). Compared to the controls, pre-Tx TVD (17.5 ± 1.3 mm/mm(2)) was lower and RBC velocity (476 ± 77 μm/s) was significantly higher. After transfusion, TVD and RBC velocity remained significantly lower and higher, respectively. In a subgroup, analysis of the transfused children with infection of TVD at baseline was lower with a larger increase after transfusion compared to anemic children without infection (ΔTVD 3.4 ± 2.6 versus ΔTVD 1.3 ± 1.5 mm/mm(2)).

Conclusion: With the rise of hemoglobin after transfusion, significant improvements of tissue perfusion were demonstrated but differences to non-anemic controls persisted. In particular, the microcirculation of anemic oncology patients with infection improved after transfusion.

What is known: • Transfusions can improve but also temporarily reduce the microcirculation. • In neonates, transfusion significantly increases total vessel density. What is New: • Pretransfusion, the microcirculation of the anemic children differed significantly from the controls. • After transfusion, the microcirculation improved but still differed from the controls. • These changes were most profound in anemic patients with concurrent infection, therefore transfusion threshholds might need to be higher.