The Placental Transfer of Gases and Fixed Acids

Open Access
Publisher Website
Google Scholar
Abstract
The blood from the umbilical vein and artery has been studied in 18 normal deliveries and in 4 cases where the infants were mildly asphyxiated. Figures are given for the oxygen tension, carbon dioxide tension, oxygen content, carbon dioxide content, pH, base excess and lactic acid. In 10 cases intervillous blood was obtained before delivery and analysed. The foetus receives 3.6 mEq/1. of oxygen and eliminates 3.6 mEq/1. of total acids. This balance shows that the foetus, at the time when the samples were taken, i.e. immediately after delivery, was in a steady state. This, together with results drawn from the intervillous measurements, shows that the analyses of cord blood presented by us, here as well as earlier, are representative of the intrauterine conditions during the last period of pregnancy. The data presented give a physiological picture of the gas exchange levels of the foetus and give figures for the calculation of the ratio between the foetal and maternal placental blood flow. The foetal placental minute volume is about 0.3 litre.