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/mm2) 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/mm2) 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/mm2).