Quantitative studies of the human neonatal circulation. II. Hemodynamic findings in early and late clamping of the umbilical cord.

Abstract

SummaryDye dilution studies by the double catheter technic were performed on 47 normal, term, newborn infants 2 1/2 to 54 hours of age. According to the time of cord clamping, the subjects were divided into two groups:Cardiac output and left‐to‐right shunt were calculated from the LA → pAo curves and, in eight instances, from the PA → LA curves by the forward triangle method. A left‐to‐right shunt across the ductus arteriosus was generally observed during the first day although at age 12 to 24 hours, this shunt was already very small. It was noted in only 1 of 10 infants over 24 hours of age. A tiny right‐to‐left shunt was observed only in 7 of 30 infants up to 12 hours of age. Systemic blood flow which was low during the first day increased by the second or third day, accompanied by a decline in systemic vascular resistance. The pulmonary and systemic vascular resistance indices were higher than those of normal older children.No significant differences in the hemodynamic findings of the two groups of infants were observed. Functional patency of the ductus venosus was observed in all 20 subjects tested.(1) early clamp group – 11 infants;(2) late clamp group – 36 infants.