Background: More than 90 percent of extremely low-birth-weight infants receive one or more transfusions of red blood cells (RBCs). The objective was to assess if RBC transfusions may induce significant changes of plasma acid-base, electrolyte, and glucose status in extremely preterm infants.
Study design and methods: Records of infants with gestational age of less than 31 weeks who were transfused with RBCs during the first week of life were reviewed (n = 61). Blood samples were collected from infants before and after transfusions to evaluate hemoglobin (Hb) level, hematocrit, acid-base, electrolyte, and glucose status. Then infants were stratified into four groups that received a RBC volume of less than 15, 15 to 20, more than 20 to 25, or more than 25 mL per kg.
Results: Infants received 20.7 (+/-1.5) mL per kg RBCs. After transfusions, a significant increase of pO(2) (p < 0.0001) and decrease of Ca(2+) (p = 0.047) and glycemia (p < 0.0001) were observed. Infants who were transfused with more than 25 mL per kg were significantly less immature, heavier, and more anemic than infants in other groups. A positive relationship was found between changes of patients' potassium plasma level and K(+) intake through RBC transfusion (r = 0.442, p = 0.008). Three (4.9%) infants developed hyperkalemia, one (1.6%) had an exacerbation of his hypocalcemia, and another (1.6%) of his hypoglycemia.
Conclusions: RBC transfusions were effective in correcting anemia in our patients and induced a slight increase of pH and pO(2) and decrease of Ca(2+) and glycemia, which were not clinically relevant. A linear direct correlation was observed between potassium intake by RBC transfusions and changes of kalemia in our infants, but there was not an increase of K(+) plasma level after transfusions.