BIO7: PAL-LR: a Reduced Resistance, Concentric-Gated Artificial Membrane Lung for Pediatric End-Stage Lung Failure

Purpose: This work focuses on the development of the Low Resistance Pediatric MLung (PAL-LR) with the goal of serving as a pumpless (pulmonary artery to left atrium) bridge-to-transplant device for small children with end-stage lung failure. Methods: The PAL-LR doubles the exposed fiber length of the Pediatric Artificial MLung. 9 PAL-LR MLungs were fabricated using polymethylpentene fibers (surface area: 0.44 m2). In vitro benchtop studies tested gas exchange and pressure drop performance (n=6). In an acute in vivo study, 3 PAL-LRs were anastomosed from the femoral vein to the jugular vein in an ovine model to assess hemocompatibility, device blood flow, pressure drop, and gas exchange. A centrifugal pump (Model 550 Bio-Console; Medtronic, Minneapolis, MN) was used pre-device to maintain flows of 1 L/min while sweep gas was supplied for each blood flow rate at a 1:1 sweep:blood flow ratio. Results: For in vitro tests, average rated blood flow (outlet SO2 of 95%) was 2.46±0.22 L/min with a pressure drop of 25.7±3.1 mmHg. At the targeted pediatric flow rate of 1 L/min, the PAL-LR pressure drop was 8.6 mmHg compared to 25 mmHg of the PAL. At rated flow, the average O2 and CO2 transfer rates were 101.75±10.81 and 77.93±8.40 mL/min, respectively. The average maximum O2 and CO2 exchange efficiencies are 215.75±22.93 and 176.99±8.40 mL/(min*m2), respectively. In vivo tests revealed an average outlet SO2 of 100%, and average pressure drop of 2±0 mmHg for a blood flow of 1.07±0.02 L/min. After 5 hours of extracorporeal use per lung, the platelets increased 3.54% for the first lung, and decreased 0.21% and 0.17% for the second and third lungs, respectively. Analysis revealed some clotting at the outlet and around gates, likely due to recirculation which will be mitigated in future revisions. Summary: Having a lower resistance, the PAL-LR is a promising step closer to a pumpless artificial membrane lung that alleviates right ventricular strain associated with idiopathic pulmonary hypertension.