Cerebral Oximetry in Ugandan Children With Severe Anemia: Clinical Categories and Response to Transfusion.

IMPORTANCE: Severe anemia, defined as a hemoglobin level of less than 5.0 g/dL, affects millions of children worldwide. The brain has a high basal demand for oxygen and is especially vulnerable to hypoxemia. Previous studies have documented neurocognitive impairment in children with severe anemia. Data on cerebral tissue oxygenation in children with severe anemia and their response to blood transfusion are limited.
OBJECTIVE: To measure hemoglobin saturation in cerebral tissue (cerebral tissue oxygen saturation [tSo2]) before, during, and after blood transfusion in a cohort of children presenting to hospital with severe anemia. DESIGN, SETTING, AND PARTICIPANTS: This was a prospective, observational cohort study conducted from February 2013 through May 2015 and analyzed in July 2015 at a university hospital pediatric acute care facility in Kampala, Uganda, of 128 children, ages 6 to 60 months who were enrolled in a larger clinical trial, with a presenting hemoglobin level of less than 5.0 g/dL and a blood lactate level greater than 5mM. Most children had either malaria or sickle cell disease. EXPOSURES: Red blood cell (RBC) transfusion given as 10 mL/kg over 120 minutes. MAIN OUTCOMES AND MEASURES: Clinical and laboratory characteristics of children with pretransfusion cerebral tSo2 levels less than 65%, 65% to 75%, and greater than 75%. Change in cerebral tSo2 as a result of transfusion.
RESULTS: Of 128 children included in the study, oximetry results in 8 cases were excluded owing to motion artifacts; thus, 120 were included in this analysis. Cerebral tSo2 values prior to transfusion ranged from 34% to 87% (median, 72%; interquartile range [IQR], 65%-76%). Eighty-one children (67%) demonstrated an initial cerebral tSo2 level (≤75%) corresponding to an oxygen extraction ratio greater than 0.36. Patients with sickle cell disease (n = 17) and malaria (n = 15) contributed in nearly equal numbers to the subgroup with an initial cerebral tSo2 (<65%). The level of consciousness, hemoglobin concentration, blood lactate level, and thigh muscle tSo2 level were poor predictors of cerebral oxygen saturation. Following RBC transfusion, the median (IQR) cerebral tSo2 level increased to 78% (73%-82%) (P < .001), but 21% of children failed to achieve a tSo2 level greater than 75%. CONCLUSIONS AND RELEVANCE: Severe anemia in children is frequently associated with low cerebral oxygenation levels as measured by near-infrared spectroscopy. Hemoglobin level and lactate concentration did not predict low cerebral tSo2 levels. Cerebral tSo2 levels increase with RBC transfusion with different patterns of response. More studies are needed to evaluate the use of noninvasive cerebral tissue oximetry in the care of children with severe anemia.