Purpose An artificial placenta would change the paradigm of treating extremely premature infants. We hypothesized that using a veno-venous extracorporeal life support (VV-ECLS) artificial placenta after ventilatory failure would stabilize premature lambs and maintain normal fetal physiologic parameters for 70h. Methods A near-term neonatal lamb model (130 days; term=145) was used. The right jugular vein (drainage) and umbilical vein (reinfusion) were cannulated with 10–12 Fr cannulas. Lambs were then transitioned to an infant ventilator. After respiratory failure, the endotracheal tube was filled with amniotic fluid, and VV-ECLS total artificial placenta support (TAPS) was initiated. Lambs were maintained on TAPS for 70h. Results Six of seven lambs survived for 70h. Mean ventilation time was 57±22min. During ventilation, mean MAP was 51±14mmHg, compared to 44±14mmHg during TAPS (p=0.001). Mean pH and lactate during ventilation were 7.06±0.15 and 5.7±2.3mmol/L, compared to 7.33±0.07 and 2.0±1.8mmol/L during TAPS (p<0.001 for both). pO2 and pCO2 remained within normal fetal parameters during TAPS, and mean carotid blood flow was 25±7.5mL/kg/min. Necropsy showed a patent ductus arteriosus and no intracranial hemorrhage in all animals. Conclusions The artificial placenta stabilized premature lambs after ventilatory failure and maintained fetal circulation, hemodynamic stability, gas exchange, and cerebral perfusion for 70h.

An artificial placenta (AP) using venovenous extracorporeal life support (VV-ECLS) could represent a paradigm shift in the treatment of extremely premature infants. However, AP support could potentially alter cerebral oxygen delivery. We assessed cerebral perfusion in fetal lambs on AP support using near-infrared spectroscopy (NIRS) and carotid arterial flow (CAF). Fourteen premature lambs at estimated gestational age (EGA) 130 days (term = 145) underwent cannulation of the right jugular vein and umbilical vein with initiation of VV-ECLS. An ultrasonic flow probe was placed around the right carotid artery (CA), and a NIRS sensor was placed on the scalp. Lambs were not ventilated. CAF, percentage of regional oxygen saturation (rSO2) as measured by NIRS, hemodynamic data, and blood gases were collected at baseline (native placental support) and regularly during AP support. Fetal lambs were maintained on AP support for a mean of 55 ± 27 hours. Baseline rSO2 on native placental support was 40% ± 3%, compared with a mean rSO2 during AP support of 50% ± 11% (p = 0.027). Baseline CAF was 27.4 ± 5.4 ml/kg/min compared with an average CAF of 23.7 ± 7.7 ml/kg/min during AP support. Cerebral fractional tissue oxygen extraction (FTOE) correlated negatively with CAF (r = -0.382; p < 0.001) and mean arterial pressure (r = -0.425; p < 0.001). FTOE weakly correlated with systemic O2 saturation (r = 0.091; p = 0.017). Cerebral oxygenation and blood flow in premature lambs are maintained during support with an AP. Cerebral O2 extraction is inversely related to carotid flow and is weakly correlated with systemic O2 saturation.