Microcirculatory assessment of red blood cell transfusion in children with severe anemia

Background: Pediatric hematology patients frequently receive red
blood all transfusions for severe anemia. Our goal was to assess
the effect of blood transfusion on the microcirculation and thus
provide information on the quality of tissue perfusion. Methods and
patients: The sublingual microcirculation was visualized with
Sidestream-Darkfield Imaging in 20 anemic (Hb: 7.2 g/dL, 95% CI
6.6-7.9) children receiving red blood cell transfusions and in age
matched healthy non-anemic controls. Functional vessel density
(FVD) was determined with a semiautomatic program. Results:
Immediately after transfusion FVD increased (13.4 versus 15 mm/mm2)
and RBC velocity (696 (598-792) versus 628 (549-707) μm/s)
decreased but FVD was always significantly lower and RBC velocity
was always higher than in the age matched control group (FVD 17
mm/mm2; RBC velocity: 486 (441-530) μm/s). FVD at baseline was
lower in patients with infections but with a larger increase after
transfusion compared to anemic children without infections (∆FVD
3.4 versus ∆FVD 1.3 mm/mm2). Hemoglobin levels and capillary
density correlated well. We did see a larger rise in FVD with
transfusion of RBCs aged < 12 days. Conclusion: Whereas
conventional monitoring methods may not be able to assess the
effect of therapies aimed to improve tissue perfusion, SDF imaging
can demonstrate improvements after transfusion but also continuous
differences to non-anemic controls. In particular, the
microcirculation of anemic oncology patients with infection
improves after transfusion. Transfusion thresholds might need to be
set higher in in such patients and fresh RBCs < 12 day of
storage should be used.