Low-Resistance, Concentric-Gated Pediatric Artificial Lung for End-Stage Lung Failure

Abstract

Children with end-stage lung failure awaiting lung transplant would benefit from improvements in artificial lung technology allowing for wearable pulmonary support as a bridge-to-transplant therapy. In this work, we designed, fabricated, and tested the Pediatric MLung-a dual-inlet hollow fiber artificial lung based on concentric gating, which has a rated flow of 1 L/min, and a pressure drop of 25 mm Hg at rated flow. This device and future iterations of the current design are designed to relieve pulmonary arterial hypertension, provide pulmonary support, reduce ventilator-associated injury, and allow for more effective therapy of patients with end-stage lung disease, including bridge-to-transplant treatment.

Figure 1.

Basic device topology of the Pediatric MLung. A, B: The components the comprise the device include (a) outer housing, (b) gate insert, (c) blood outlet, (d, e) end caps, (f) fiber bundles, and (g) the blue silicone potting. C: Side view of a Pediatric MLung; the fibers are oriented vertically within the housing in this image. D: Top view of a Pediatric MLung with illustration of the blood flow paths (red arrows).

Figure 2.

Isometric views of the 3D model (A) and a cross-section through a midplane (B) of the pediatric MLung having 3 cm fiber length. Velocity (C) and pressure (D) profiles through the mid-plane of the Pediatric MLung were generated with Solidworks Flow Simulation. 3D, three-dimensional.

Figure 3.

Oxygenation (A, B) and pressure drop (C) of pediatric MLung during benchtop blood flow testing (n = 6).

Figure 4.

Device flow rate (circles) and corresponding pressure drop (triangles) during 6 hours of arteriovenous blood flow from adult sheep. Three Pediatric MLungs were tested (A–C) for 6 hours or until device flow was reduced to 5% of initial flow.

Figure 5.

Systemic ACT (circles) and device resistance (triangles) during 6 hours of arteriovenous blood flow from adult sheep. Three Pediatric MLungs were tested (A–C) for 6 hours or until device flow was reduced to 5% of initial flow. ACT, activated clotting time.

Figure 6.

Platelet count (circles) and WBC count (triangles) during 6 hours of arteriovenous blood flow from adult sheep. Three Pediatric MLungs were tested (A–C) for 6 hours or until device flow was reduced to 5% of initial flow. WBC, white blood cell.

Figure 7.

CO₂ removal efficiency (circles) at varied sweep flow (triangles) of three Pediatric MLungs that were tested for 6 hours or until device flow was reduced to 5% of initial flow. Datapoints not gathered were due to dilution of the sample by sweep gas making the collected CO₂ concentration below the detection limit of the blood gas machine (average ± SEM, n = 3, *n = 2, no error bar: n = 1). CO₂, carbon dioxide; SEM, standard error mean.

Figure 8.

Device flow rate (diamonds) and corresponding pressure drop (squares) during 6 hours of blood flow from adult sheep. Three Pediatric MLungs were tested (A–C) for 6 hours (with exception of plot C, in which the experiment was ended voluntarily after occlusion of the rPA did not result in blood flow of at least 0.75 L/min). Oxygenation rate was measured throughout each experiment (D). rPA, right pulmonary artery.