Long-term animal model of venovenous extracorporeal membrane oxygenation with atrial septal defect as a bridge to lung transplantation.

<p>This study evaluated the effectiveness of an atrial septal defect (ASD) with venovenous extracorporeal membrane oxygenation (vv-ECMO) as a bridge to transplantation. Sheep (56 ± 3 kg; n = 7) underwent a right-sided thoracotomy to create the ASD (diameter = 1 cm) and place instrumentation and a pulmonary artery (PA) occluder. After recovery, animals were placed on ECMO, and the PA was constricted to generate a twofold rise in right ventricular (RV) systolic pressure. Sheep were then maintained for 60 hours on ECMO, and data were collected hourly. Five sheep survived 60 hours. One sheep died because of a circuit clot extending into the RV, and another died presumably because of an arrhythmia. Mean right ventricular pressure (mRVP) was 19 ± 3 mm Hg at baseline, averaged 27 ± 7 mm Hg over the experiment, but was not statistically significant (p = 0.27) due to one sheep without an increase. Cardiac output was 6.8 ± 1.2 L/min at baseline, averaged 6.0 ± 1.0 L/min during the experiment, and was statistically unchanged (p = 0.34). Average arterial oxygen saturation and PCO2 over the experiment were 96.8 ± 1.4% and 31.8 ± 3.4 mm Hg, respectively. In conclusion, an ASD combined with vv-ECMO maintains normal systemic hemodynamics and arterial blood gases during a long-term increase in RV afterload.</p

Development of an artificial placenta I: pumpless arterio-venous extracorporeal life support in a neonatal sheep model.

PURPOSE: Effective treatment of respiratory failure in premature infants remains an unsolved problem. The development of an artificial placenta, in the form of a pumpless arteriovenous extracorporeal life support (AV-ECLS) circuit that maintains fetal circulation, is an appealing alternative. METHODS: A near-term (140 d/term = 145 days) neonatal lamb model was used (n = 7). Fetuses were exposed by hysterotomy, and flow probes were placed on the ductus arteriosus, aorta, and carotid artery. Catheters were placed into the umbilical vessels, and pumpless AV-ECLS was initiated. Fetuses were submerged in a warm saline bath, and support was maintained for up to 4 hours. RESULTS: Mean initial device flow was 383 mL/min but steadily declined to 177 mL/min at 4 hours. Mean initial pO(2) was 24 mm Hg and 18 mm Hg at 4 hours. Initial mean pCO(2) was 60 mm Hg and declined to 42 mm Hg at 4 hours. Mean arterial pressure was initially 43 mm Hg and decreased to 34 mm Hg at 4 hours. Flow in the ductus arteriosus was maintained for 4 hours. Of 7 fetuses, 5 survived 4 hours of support. CONCLUSIONS: Pumpless AV-ECLS can support gas exchange and maintain fetal circulation in a neonatal lamb model for a 4-hour period. Prolonged support (>4 hours) is hampered by high cannula resistance and declining device flow.</p