Impact of red blood cell transfusion on regional cerebral oxygen saturation during pediatric ECMO

Background: Low cerebral regional tissue oxygenation (crSO2) is associated with unfavorable neurological outcomes in children requiring extracorporeal membrane oxygenation (ECMO) support. Red blood cell (RBC) transfusion can improve brain oxygenation and crSO2 has been proposed as a noninvasive monitoring tool that could aid in RBC transfusion decision-making. However, how crSO2 responds to RBC transfusion is largely unknown.

Study design and methods: This was a retrospective, observational cohort study of all patients <21 years supported on ECMO at a single institution from 2011 to 2018. Transfusion events were grouped by pre-transfusion hemoglobin concentration (<10, 10- < 12, and ≥ 12 g/dL). Post- versus pre-transfusion crSO2 changes were analyzed using linear mixed-effects models.

Results: The final cohort included 830 transfusion events in 111 patients. Hemoglobin increased significantly post- versus pre-RBC transfusion (estimated mean increase of 0.47 g/dL [95% CI, 0.35-0.58], p < .001), as did crSO2 (estimated mean increase of 1.82 percentage points [95% CI, 1.23-2.40], p < .001). Larger improvements in crSO2 were associated with lower pre-transfusion crSO2 values (p < .001). There was no difference in mean change in crSO2 across the three hemoglobin groups in unadjusted analysis (p = .5) or after adjusting for age, diagnostic category, and pre-transfusion rSO2 (p = .15). Pre-transfusion crSO2 was <50% for 112 of 830 (13.5%) transfusion events, with only 30 (26.8%) crSO2 measurements noted to increase ≥50% post-transfusion.

Discussion: Among neonatal and pediatric patients on ECMO support, there was a statistically significant increase in crSO2 following RBC transfusion, although clinical significance needs to be investigated further. The effect was strongest among patients with lower crSO2 pre-transfusion.