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The effect of changes in blood gas tension upon the renin‐angiotensin system of the newborn infant
Author(s) -
TETLOW HAZEL J.,
PIPKIN FIONA BROUGHTON
Publication year - 1983
Publication title -
bjog: an international journal of obstetrics and gynaecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.157
H-Index - 164
eISSN - 1471-0528
pISSN - 1470-0328
DOI - 10.1111/j.1471-0528.1983.tb06760.x
Subject(s) - cord blood , renin–angiotensin system , vaginal delivery , caesarean section , anesthesia , umbilical cord , venous blood , vein , medicine , carbon dioxide , physiology , blood pressure , pregnancy , chemistry , biology , anatomy , organic chemistry , genetics
Summary. Renin and renin‐substrate concentrations were measured in the paired umbilical artery and vein blood of 20 babies born by elective caesarean section, and 36 babies born vaginally. Blood pH, carbon dioxide tension and oxygen tension were measured in all samples. Babies born vaginally were significantly more acidaemic than those delivered by caesarean section. The cord artery blood also had a significantly greater carbon dioxide tension at vaginal delivery. A decrease in pH of either cord artery or vein blood, irrespective of mode of delivery, was associated with an increase in renin concentration. Renin‐substrate concentration tended to be lower in the cord vein blood of acidaemic babies born vaginally, such that the ratio renin: renin‐substrate concentration was negatively correlated with pH. At caesarean section the renin concentration of cord vein blood was positively correlated with carbon dioxide tension and increased dramatically at oxygen tensions <3kPa. This was not observed in babies born vaginally, but the cord artery substrate concentration in these infants was positively correlated with carbon dioxide tension. Thus changes in the renin‐angiotensin system at birth may partly be affected by blood gas tension.