A STUDY OF FETAL ACID-BASE BALANCE DURING CAESAREAN SECTION UNDER THE ANESTHESIA

Abstract

In the neonates delivered by normal vaginal deliveries or caesarean section under anesthesia, the acid-base balance was studied with Astrup-micro-apparatus. Furthermore, the uterine regional blood flow was measured in nonpregnant and pregnant rabbits, using thermal flowmeters:
1) Metabolic acidosis of the mother was reflected on the neonate in both groups of the normal vaginal delivery and the caesarean section.
2) PO₂ of the neonate delivered by the normal vaginal delivery showed higher value compared against those of the caesarean section and this difference was significant statistically (P<0.001) .
3) For anesthesia for the caesarean section:
i) Those which would induce depression of blood pressure and/or peripheral vasoconstriction in the mother, such as spinal anesthesia and cyclopropane anesthesia, reduced PO₂ of the neonate.
ii) In case of other inhalation anesthetics, there were not any particular relationships between the kind of anesthetics and PO₂ of the neonate, insofar as the blood pressure of the mother was maintained at the normal level; it was concluded that exchange from nitrous-oxide-oxygen mixture to pure oxygen inhalation was needless after laparotomy.
4) No correlation was discernible between PO₂ of the neonate and Apgar score.
5) No particular aggravation of acid-base balance was recognized in cases of the emergency caesarean section compared with the elective one.
6) Bathing of the neonate after delivery improved respiration, metabolic acidosis, general condition, and peripheral circulation.
7) In the rabbit, hyperventilation caused a moderate decrease of uterine blood flow.