LOW BLOOD VOLUME WITH NORMAL SYSTEMIC BLOOD PRESSURE IN INFANTS WITH HYALINE MEMBRANE DISEASE (HMD)

Abstract

The central circulating blood volume (CCBV) was evaluated in 17 neonates with respiratory distress, 6 of whom had HMD. The infants were evaluated clinically and by strict radiographic criteria before entering the study at 1-2 hours of age. No small-for-dates infants were included. Measurements using I125 albumin were made on each infant at 4 & 24 hours. Mean pressures were measured in the aorta continuously for 12 hours and at 24 hours. Hematocrit determinations were done at birth, 4 & 24 hours. The mean blood volume of infants with HMD and other forms of respiratory distress was 86.6 and 100 ml/kg respectively (P < 0.01). The difference was due to low red cell volume, mean 38.2 and 47.5 ml/kg (P < 0.02). The hematocrit values at birth and 4 hours were not statistically different indicating that low CCBV in the HMD group is not the result of an inadequate placental transfusion. It is curious that the CCBV at 4 & 24 hours was not statistically different despite whole blood or other fluid infusion. Mean pressures of each group during the first 12 hours and at 24 hours were not statistically different and correlated well with norms previously established for prematures. Our data show that 1) blood pressure and hematocrit measurements are poor parameters for estimating CCBV; 2) the low red cell volume in HMD appears to exist prior to delivery; 3) and implies that vasomotor activity adequately maintains mean aortic pressures in the HMD group.