Oxygenation in fetal lambs supported by extrauterine right atrium to artery extracorporeal membrane oxygenation

Abstract

OBJECTIVE: Our purpose was to determine the adequacy of oxygenation, particularly cranial and cardiac oxygenation, in exteriorized fetal lambs on right atrium to artery extracorporeal membrane oxygenation. STUDY DESIGN: Thirteen fetal lambs were placed on right atrium to artery extracorporeal membrane oxygenation between the gestational ages of 113 and 133 days. Various P O 2 and oxygen saturation (S O 2) values were obtained by varying the oxygen concentrations at the oxygenator membrane. Blood gases, pH, and S O 2 were observed on samples taken before and after membrane oxygenation from the left ventricle and through the cranial carotid arterial catheter. These were compared with control values obtained before the cessation of umbilical circulation. Fetal coronary oxygenation was represented by left ventricle P O 2 and S O 2 and cranial oxygenation by carotid artery P O 2 and S O 2. RESULTS: We classified oxygen saturation as low, medium, and high on the basis of the level of postmembrane S O 2. Carotid artery cranial oxygenation in the low S O 2 group was equivalent to control values, but that in the medium and high S O 2 groups was significantly higher than in the control group. Left ventricle oxygenation was consistently lower than cranial oxygenation in any S O 2 group. In the low group left ventricle oxygenation was significantly lower than the control values. CONCLUSIONS: Right atrium to artery extracorporeal membrane oxygenation appears sufficient to oxygenate the fetal cranial circulation but may be inadequate for the efficient distribution of oxygenated blood into the left ventricle and thus the coronary circulation. (A M J O BSTET G YNECOL 1996;174:535-9.)