Development of a Novel, Low-Resistance Pediatric Artificial Lung for Long-Term Support

Background: For children with severe lung disease that cannot wean from ECMO, an implantable artificial lung would permit extubation and support gradual lung recovery from acute disease or provide a bridge to transplantation. We evaluate the function of the novel Pediatric MLung—an efficient, implantable, pumpless artificial lung developed specifically for children—in healthy animal subjects.

Methods: Adolescent “mini sheep” weighing 12-20 kg underwent left anterior thoracotomy. Vascular access was obtained in the main pulmonary artery (device inflow) and the left atrium (device outflow) with 28 Fr cannulae. Heparin was infused for therapeutic anticoagulation. The MLung was exchanged when device flows were below 200 mL/min or device outlet oxygen saturation was less than 95%. Animals were euthanized after 7 days. Wilcoxon Signed-Rank Test was used to compare differences from the start to the end of the experiment.

Results: Six sheep survived 7 days and used a total of 10 lungs—3 sheep used 1 lung, 2 used 2 lungs, and 1 used 3 lungs. Mean arterial pressure (MAP), PaCO2, and PaO2 remained within normal across the 7 days. Cardiac output was 2.3 +/- 0.6 L/min. Flow through the device averaged 633 +/- 258 mL/min, or 30 +/- 16% of cardiac output. Average outlet oxygen saturation was 99.2 +/- 3.4%. Pressure drop across the device was 4.4 +/- 3.4 mmHg. Resistance through the device was 7.2 +/- 5.2 mmHg/L/min. Median platelet count was 441,000 after 7 days, which did not differ significantly from the median count at baseline of 308,000 (p>0.05). There was one bleeding complication involving a hemothorax from incisional bleeding.

Conclusion: The Pediatric MLung provides low-resistance gas-exchange support without significant effects on hemodynamics in normal animals.