A Comparison of the Rheologic Properties of Neonatal and Adult Blood

Abstract

ABSTRACT. A number of studies have indicated that the emphasis on low shear rate viscosity and rouleaux-related pherheologic properties of neonatal blood are different from nomena. those of the adult. The frequent administration of blood components to the neonate during intensive care make it important that these differences be established and their MATERIALS AND METHODS causes understood. The purpose of this study was to make a detailed comparison of the rheologic properties of nee-Blood was obtained from healthy adults by venesection, natal and adult blood, with particular emphasis on low and from the umbilical vein of neonates immediately after shear rate viscosity and rouleaux-related phenomena. The clamping of the cord at delivery. In each case, it was anticoaguviscometric data was obtained from seven preterm (PT) lated with 12.5 U/mL of heparin. The babies were all born and l8 term (NT) babies and with those vaginally and did not require resuscitation. They were of normal l8 (A)-In the present study, "iscometry was wt for gestation age. There were too few preterm babies to group performed Over a wide range Of shear rates, O a 3 them according to gestational age, which ranged from 24 to 35 130 s-', and the low shear rate data were with wk, thus all babies of less than 37 wk were classified as preterm. direct measurement of rouleaux formation using the MY-he adults had an age range of 24 to 50 y with a median age of renne Erythrocyte Aggregometer. A major factor leading 30. to the viscometric differences observed was the high hem-1, a pilot survey, the rheologically important variables-hematOcrit in the newborn (46.8 + 2.1% PT, 52.8 + atocrit, plasma viscosity, and plasma fibrinogen concentration-6-1% NT, 44-1 * 2.5% A 40.5 + A females)-were compared between pre-and normal term babies and adults.ow ever, this tended to be compensated for by the lower This was followed by a more comprehensive hemorheologic plasma (Iso5 * 0.07 mPas PT, * 0-14 mPas study that included the measurement of blood viscosity over a NT,* O e o 8 mPas A-n0 sex difference) and reduced wide range of shear rates. These viscometric studies were made rOuleaux in the and more according to the ICSH Guidelines (7) on blood at native hemamarked in the preterm baby. The lowered levels red tocrit and, after adjustment by adding or subtracting autologous aggregation were found not to be due to cellular differences plasma, at 45%. The hematocrit was measured by microcentribetween the adults and the babies but rather to differing fugation without correction for trapped plasma, plasmaThe presence the fetal variant In some experiments, washed cells were used. The cells were fibrinogen and low levels of immunoglobulins, especially washed, by alternate centrifugation and aspiration of supernaIgM and IgA, are likely be particular imp0rtance. tant, using isotonic PBS. The cells were finally suspended at a (Pediatv Res 25457-460, 1989) hematocrit of 45% in PBS or PBS containing adult human fibrinogen (Kabi Pharmaceuticals, Stockholm, Sweden). Fibrinog...

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