A NEW, RAPID METHOD FOR ESTIMATION OF RED CELL MASS IN NEONATES GIVEN BLOOD TRANSFUSION

We have estimated red cell mass (RCM), using a new method based on dilution of HbF by donor HbA, in 31 infants requiring blood transfusion (Tx). In Group 1, a third of the babies, Tx was for acute, early losses within 10 days of birth, whereas in Group 2 (20 infants), Tx was usually for ‘anaemia of prematurity’ compounding earlier, more gradual blood losses & was given between age 16 and 70 days, median 31 days, after birth. In Group 1 the low values for RCM are associated with marked hypovolaemia in those infants undergoing haemodilution after acute blood losses: RCM (x ± SD) = 17.1 ± 3.9 ml/kg (Range 12.6-23.1) Total blood volume (TBV) 54.2 ± 14.5 ml/kg (Range: 29.4-77.0) Hb 10.6 ± 1.3 g/dl (Range 9.0-13.6) Group 2: severe hypovolaemia also marks the later anaemia in such infants, since the (calculated) plasma volumes are contracted, partly masking the anaemia: RCM = 19.3 ± 6.7 ml/kg (Range: 12.5-39.9) TBV = 65.9 ± 22.3 ml/kg (Range: 38.0-137.6) Hb = 9.6 ± 1.2 g/dl (Range: 7.5-11.4) This method extends assessment of the impairment of O2 supply from the blood, after perinatal blood losses and in later anaemias.