RELATIONSHIP BETWEEN BLOOD-GAS VALUES AND HORMONAL RESPONSE TO ACUTE HYPOXEMIA IN FETAL SHEEP

We examined the relationship of fetal plasma immunoreactive adrenocorticotropic hormone (IR- ACTH), arginine vasopressin (AVP) and cortisol to fetal arterial pO2 (PaO2), oxygen saturation (SaO2), change (Δ) in PaO2 (ΔPaO2) or SaO2 (ΔSaO2) in fetal sheep at 125-139 days of gestational age. Fetal sheep were exposed to two levels of hypoxemia induced by altering the inspired percent oxygen to the mother for 1 h without fetal acidemia. Fetal carotid arterial IR-ACTH, AVP and cortisol concentrations during hypoxemia were correlated with fetal PaO2, SaO2, ΔPaO2 and ΔSaO2 by applying simple regression analysis. For IR-ACTH, a strong correlation was obtained with SaO2. ΔSaO2 and ΔPaO2 after log transformation to IR-ACTH. For AVP, strong correlation coefficients were obtained with ΔSaO2, SaO2. ΔPaO2 and Pa2 after reciprocal transformation to AVP, but for cortisol a strong correlation was obtained only with ΔPaO2 after log transformation to cortisol. We conclude that during fetal hypoxemia without acidemia, there is a strong correlation between IR-ACTH and SaO2, ΔSaO2, ΔPaO2 but not PaO2. between AVP and ΔSaO2, SaO2, ΔPaO2, or PaO2, and between cortisol and ΔPa2. © 1990 S. Karger AG, Basel.