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In Vitro Characterization of the Pittsburgh Pediatric Ambulatory Lung

Orizondo, Ryan A.*; May, Alexandra G.*,†; Madhani, Shalv P.*,‡; Frankowski, Brian J.*; Burgreen, Greg W.§; Wearden, Peter D.*,¶,‖; Federspiel, William J.*,†,‡,#

doi: 10.1097/MAT.0000000000000711

Acute and chronic respiratory failure are a significant source of pediatric morbidity and mortality. Current respiratory support options used to bridge children to lung recovery or transplantation typically render them bedridden and can worsen long-term patient outcomes. The Pittsburgh Pediatric Ambulatory Lung (P-PAL) is a wearable pediatric blood pump and oxygenator (0.3 m2 surface area) integrated into a single compact unit that enables patient ambulation. The P-PAL is intended for long-term use and designed to provide up to 90% of respiratory support in children weighing 5–25 kg. Computational fluid dynamics and numerical gas exchange modeling were used to design the P-PAL and predict its performance. A P-PAL prototype was then used to obtain pressure versus flow curves at various impeller rotation rates using a blood analog fluid. In vitro oxygen exchange rates were obtained in blood in accordance with ISO standard 7199. The normalized index of hemolysis (NIH) was measured over a 6 hour period at blood flow rates of 1 and 2.5 L/min. The P-PAL provided blood flows of 1–2.5 L/min against the pressure drop associated with its intended-use pediatric cannulas. The oxygen exchange rate reached a maximum of 108 ml/min at a blood flow rate of 2.5 L/min and met our respiratory support design target. Device-induced hemolysis was low with NIH values of 0.022–0.027 g/100 L in the intended blood flow rate range. In conclusion, the current P-PAL design met our pumping, oxygenation, and hemolysis specifications and has the potential to improve treatment for pediatric respiratory failure.

From the *McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania

Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania

Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania

§Computational Fluid Dynamics Group, Center for Advanced Vehicular Systems, Mississippi State University, Starkville, Mississippi

Department of Cardiothoracic Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania

Cardiac Center, Nemours Children’s Hospital, Orlando, Florida

#Department of Critical Care Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.

Submitted for consideration June 2017; accepted for publication in revised form October 2017.

Supported by the National Institutes of Health (grant numbers R01HL117637 and R01HL135482), the McGowan Institute for Regenerative Medicine, and the Pediatric Device Initiative.

Disclosures: William J. Federspiel is the head of the scientific advisory board for and an equity holder in ALung Technologies. No other authors have any conflicts of interest to disclose.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text, and links to the digital files are provided in the HTML and PDF versions of this article on the journal’s Web site (

Correspondence: Ryan A. Orizondo, PhD, McGowan Institute for Regenerative Medicine, 3025 East Carson Street, Pittsburgh, PA 15203. Email:

Copyright © 2018 by the American Society for Artificial Internal Organs