Mm Hg O2 Research Articles

The purpose of this study was to determine whether there is a relationship between spontaneous fetal respiratory movements (FRM) and fetal blood gases. A hysterotomy was performed at 105-120 days gestation in 3 pregnant ewes and 6 pregnant goats; catheters were introduced into the fetal carotid artery, fetal trachea and amniotic cavity. Thereafter observations were made on unanesthetized animals for periods of 3 to 27 days. Periods of apnea and FRM were identified from simultaneous recording of intratracheal and intraamniotic pressure; samples of fetal blood were obtained during both apnea and FRM. In both fetal lambs and fetal goats, mild hypoxemia was present during episodes of FRM and there were significant differences in blood oxygen values for the group of fetal goats; mean PO2 was 29.9 mmHg vs. 27.6 mmHg (P<0.01) and mean O2 saturation was 75.6% vs. 69.7% (P<0.01). There were no significant differences for pH, PCO2 and base excess. However, when blood samples were analyzed in relation to the amplitude of FRM, there was a significant increase of PCO2 with increasing amplitude of FRM. These observations suggest that, in the ovine fetus, mild fluctuation of blood gases are present even under relatively undisturbed intrauterine conditions and that these are associated with FRM; it is speculated that a cause and effect relationship may be present.