[Fundamental and experimental studies on fetal biochemical monitoring accomplished by ion-sensitive field-effect transistor pH and PCO2 sensors].
Materno-fetal pH and PCO2 were measured continuously, using newly-developed transistor pH and PCO2 sensors placed in both arteries and peripheral tissues of 12 pregnant goats near term. Maternal BP, FHR and fetal tcPO2 were also recorded simultaneously. As results: (1) Maternal oxygen inhalations caused consistent increases of fetal tcPO2 from 21 to 29 mmHg, in average. (2) When various concentrations of CO2 were inhaled by the mother, maternal PaCO2 rapidly increased to peak levels near to FiCO2, followed by swift decreases to control values on cessation of inhalation. Fetal PaCO2 increased rather slowly. High levels of hypercarbia persisted even after falls in maternal PaCO2. (3) Repeated maternal CO2 inhalations caused remarkable CO2 accumulations within fetal bodies. Maternal 10% CO2-90%O2 and 20%CO2-80%O2 inhalations resulted in remarkable increases of fetal tcPO2. (4) FHR changes appeared to be more dependent on fetal oxygenation, rather than fetal respiratory, or metabolic acidosis. (5) Maternal lactate administrations caused fetal metabolic acidosis. (6) Maternal NaHCO3 infusions resulted in increases of maternal pH and materno-fetal PaCO2, as well as falls in fetal pH. (7) Maternal nor-epinephrine produced remarkable decreases of FHR, fetal tcPO2 and pH, as well as increases of fetal PaCO2. (8) Maternal phenylephrine caused mild decreases of FHR and fetal tcPO2. Therefore, it was concluded that continuous materno-fetal bloodgas monitorings would provide better knowledge regarding placental respirations, being probably applicable to fetal evaluations in clinical obstetrics.
D000818:Animals; D002245:Carbon Dioxide / Q000097:blood*; D002404:Catheterization; D005260:Female; D005323:Fetal Monitoring / Q000379:methods*; D006041:Goats; D006863:Hydrogen-Ion Concentration; D008431:Maternal-Fetal Exchange; D011247:Pregnancy; D014173:Transistors, Electronic
D002245:Carbon Dioxide