A STUDY OF THE ACID-BASE BALANCE OF FETAL SHEEP AND GOATS

¹ Department of Physiology, Yale University School of Medicine, New Haven, Connecticut

By means of indwelling plastic catheters the pCO₂, pH and bicarbonate levels of the maternal and fetal plasmas have been compared in sheep and goats by repeated sampling during periods up to 24 hr. Comparisons have been made in "steady state" conditions, as well as during and following NH₄Cl infusion of the mother. The results demonstrate: (1) that the pCO₂ of the blood of the umbilical artery is about 20 mm. Hg higher than the maternal arterial pCO₂ in "steady state" conditions; (2) that this difference remains relatively stable despite wide variations in the pCO₂ of the maternal arterial blood; (3) that the bicarbonate level of the fetal plasma is virtually independent of the maternal over a 24-hr. period; and (4) in some circumstances the pH's of the maternal and fetal bloods may change in opposite directions.