The effects of extracorporeal membrane oxygenation on hypoxic fetal lambs

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Objective: The purpose of this study was to determine the applicability of using venoarterial or venovenous extracorporeal membrane oxygenation (ECMO) techniques to support fetal oxygenation in utero.Study Design: An ECMO system with centrifugal pump was applied to fifteen chronically instrumented fetal lambs, ranging from 125 to 133 days of gestation, with the placental circulation intact. Blood was obtained through a 12 Fr. double lumen catheter inserted into the right atrium. After oxygenation the blood was returned through a 9 Fr. single lumen catheter in carotid artery (VA ECMO) or the other lumen in the right atrium (VV ECMO). After fetal hypoxia was experimentally produced by reducing FiO2 of the mother, the VA ECMO started to maintain the fetal oxygenation for 30 minutes, and switched to the VV ECMO. We compared fetal blood gases of cranial carotid and axillar arteries with the both routes of ECMO. We also measured fetal plasma ANP, Catecholamine, AVP and Cortisol. Moreover, we … More determined the distribution of oxygenated blood flow in each period during placental circulation intact by non-radioactive colored microspheres.Results: The ECMO blood flow rate through the double lumen catheter during VA or VV ECMO ranged at approximately 50-60 ml/min. Fetal cranial carotid arterial pO2 was decreased by reducing FiO2 of the mother. After maintaining of VA ECMO or VV ECMO, the pO2 was recovered to the control level under advantaging fetal acidosis. The fetal heart rate and blood pressure were not significantly altered during the experiments. Fetal plasma Catecholamine, AVP and Cortisol increased through the experiments, however fetal plasma ANP decreased during the VV ECMO. The VV ECMO more closely approximated normal intact placental-fetal blood flow distribution than the VA ECMO in fetal lambs.Conclusion: The VA or VV ECMO maintained normal fetal oxygenation during maternal hypoxia The oxygenated blood should be returned to fetal right atrium for maintenance of fetal cardiac oxygenation and fetal physiological circulation. This study indicated that the VV ECMO could maintain fetal oxygenation effectively and less traumatically on hypoxic fetal lambs. Less