座位分娩にて出生した新生児の循環血液量の検討

Abstract

Measurement of total blood volume (TBV) and red cell volume (RCV) is indispensable to understand the physiological background of hemodynamic change in newborn infants. A technique for measuring the blood volume of newborn infants was established by using non-radioactive 50Cr. Red blood cells (RBC) labeled with enriched stable isotope 50Cr were injected into the newborn infants. Blood samples were subsequently taken every few days. After the RBC portion was separated and dried, the dilution rate of the RBC was quantitated by neutron activation analysis.The purpose of this investigation was to observe the change of TBV and RCV in full term neonates delivered in a sitting position. The effect of early and delayed cord clamping of the neonates upon TBV was also studied within the first 120 hours after birth. Studies were performed on 23 neonates. 10 were delivered in a sitting position, 7 in a supine position and 6 by cesarean section.Serial measurements of TBV (RCV) in the neonates delivered in a sitting position whose cords were clamped early have shown an average volume of 63.4±4.8 (35.5±4.9)ml/kg at 1.5 hour, 94.4±11.8 (42.2±2.3)ml/kg at 24 hours and 86.0±10.0 (41.5±5.8)ml/kg at 72 hours after birth. The neonates whose cords were clamped late had about 20-30% higher TBV and RCV than the early-clamped neonates within 120 hours after birth. Under early cord clamping conditions, there was no significant difference in TBV and RCV just after birth between neonates delivered in a sitting position and those in a supine position.