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Shin S, Nasim U, O'Connor H, Hong Y. Progress towards permanent respiratory support. Curr Opin Organ Transplant 2024:00075200-990000000-00129. [PMID: 38990111 DOI: 10.1097/mot.0000000000001163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/12/2024]
Abstract
PURPOSE OF REVIEW Although lung transplantation stands as the gold standard curative therapy option for end-stage lung disease, the scarcity of available organs poses a significant challenge in meeting the escalating demand. This review provides an overview of recent advancements in ambulatory respiratory assist systems, selective anticoagulation therapies that target the intrinsic pathway, and innovative surface coatings to enable permanent respiratory support as a viable alternative to lung transplantation. RECENT FINDINGS Several emerging ambulatory respiratory assist systems have shown promise in both preclinical and clinical trials. These systems aim to create more biocompatible, compact, and portable forms of extracorporeal membrane oxygenation that can provide long-term respiratory support. Additionally, innovative selective anticoagulation strategies, currently in various stages of preclinical or clinical development, present a promising alternative to currently utilized nonselective anticoagulants. Moreover, novel surface coatings hold the potential to locally prevent artificial surface-induced thrombosis and minimize bleeding risks. SUMMARY This review of recent advancements toward permanent respiratory support summarizes the development of ambulatory respiratory assist systems, selective anticoagulation therapies, and novel surface coatings. The integration of these evolving device technologies with targeted anticoagulation strategies may allow a safe and effective mode of permanent respiratory support for patients with chronic lung disease.
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Affiliation(s)
- Suji Shin
- Department of Biomedical Engineering, Carnegie Mellon University
| | - Umar Nasim
- Department of Biomedical Engineering, Carnegie Mellon University
| | - Hassana O'Connor
- Department of Biomedical Engineering, Carnegie Mellon University
| | - Yeahwa Hong
- Department of Biomedical Engineering, Carnegie Mellon University
- Department of Surgery, the University of Pittsburgh Medical Center
- Department of Cardiothoracic Surgery, the University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania (PA), USA
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Roberts KG, Umei N, Shin S, Lai A, Comber EM, Ichiba S, Chopra GK, Skoog DJ, Bacchetta MD, Cook KE. Pilot Testing of a Lightweight, Pulmonary Assist System in an Ambulatory Sheep Model of Destination Therapy Respiratory Support. ASAIO J 2024; 70:e23-e26. [PMID: 37578993 DOI: 10.1097/mat.0000000000002030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2023] Open
Abstract
A new, lightweight (2.3 kg), ambulatory pulmonary assist system (PAS) underwent preliminary evaluation in ambulatory sheep. The PAS was purposefully designed for long-term extracorporeal respiratory support for chronic lung disease and utilizes a novel, small (0.9 m 2 surface area) gas exchanger, the pulmonary assist device, with a modified Heart Assist 5 pump fitting in a small wearable pack. Prototype PAS were attached to two sheep in venovenous configuration for 7 and 14 days, evaluating ability to remain thrombus free; maintain gas exchange and blood flow resistance; avoid biocompatibility-related complications while allowing safe ambulation. The PAS achieved 1.56 L/min of flow at 10.8 kRPM with a 24 Fr cannula in sheep one and 2.0 L/min at 10.5 kRPM with a 28 Fr cannula in sheep 2 without significant change. Both sheep walked freely, demonstrating the first application of truly ambulatory ECMO in sheep. While in vitro testing evaluated PAS oxygen transfer rates of 104.6 ml/min at 2 L/min blood flow, oxygen transfer rates averaged 60.6 ml/min and 70.6 ml/min in studies 1 and 2, due to average hemoglobin concentrations lower than humans (8.9 and 10.5 g/dl, respectively). The presented cases support uncomplicated ambulation using the PAS.
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Affiliation(s)
- Kalliope G Roberts
- From the Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Nao Umei
- Department of Surgical Intensive Care Medicine, Nippon Medical School, Tokyo, Japan
| | - Suji Shin
- From the Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Angela Lai
- From the Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Erica M Comber
- From the Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Shingo Ichiba
- Department of Surgical Intensive Care Medicine, Nippon Medical School, Tokyo, Japan
| | | | - David J Skoog
- Advanced Respiratory Technologies, Pittsburgh, Pennsylvania
| | - Matthew D Bacchetta
- Department of Thoracic Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Keith E Cook
- From the Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania
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Ukita R, Patel YJ, Kelly Wu W, Francois SA, Cortelli M, Johnson CA, Cardwell N, Talackine JR, Stokes JW, Grogan W, Mentz M, Tracy KM, Harris TR, Tucker W, Simonds E, Demarest CT, Cook KE, Skoog DJ, Rosenzweig EB, Bacchetta M. Ambulatory 7-day mechanical circulatory support in sheep model of pulmonary hypertension and right heart failure. J Heart Lung Transplant 2024; 43:293-302. [PMID: 37907183 PMCID: PMC10842834 DOI: 10.1016/j.healun.2023.10.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2023] [Revised: 10/11/2023] [Accepted: 10/22/2023] [Indexed: 11/02/2023] Open
Abstract
BACKGROUND Right heart failure is the major cause of death in pulmonary hypertension. Lung transplantation is the only long-term treatment option for patients who fail medical therapy. Due to the scarcity of donor lungs, there is a critical need to develop durable mechanical support for the failing right heart. A major design goal for durable support is to reduce the size and complexity of devices to facilitate ambulation. Toward this end, we sought to deploy wearable mechanical support technology in a sheep disease model of chronic right heart failure. METHODS In 6 sheep with chronic right heart failure, a mechanical support system consisting of an extracorporeal blood pump coupled with a gas exchange unit was attached in a right atrium-to-left atrium configuration for up to 7 days. Circuit performance, hematologic parameters, and animal hemodynamics were analyzed. RESULTS Six subjects underwent the chronic disease model for 56 to 71 days. Three of the subjects survived to the 7-day end-point for circulatory support. The circuit provided 2.8 (0.5) liter/min of flow compared to the native pulmonary blood flow of 3.5 (1.1) liter/min. The animals maintained physiologically balanced blood gas profile with a sweep flow of 1.2 (1.0) liter/min. Two animals freely ambulated while wearing the circuit. CONCLUSIONS Our novel mechanical support system provided physiologic support for a large animal model of pulmonary hypertension with right heart failure. The small footprint of the circuit and the low sweep requirement demonstrate the feasibility of this technology to enable mobile ambulatory applications.
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Affiliation(s)
- Rei Ukita
- Vanderbilt University Medical Center, Department of Cardiac Surgery, Nashville, TN, USA
| | - Yatrik J Patel
- Vanderbilt University Medical Center, Department of Cardiac Surgery, Nashville, TN, USA
| | - W Kelly Wu
- Vanderbilt University Medical Center, Department of Cardiac Surgery, Nashville, TN, USA
| | - Sean A Francois
- Vanderbilt University Medical Center, Department of Cardiac Surgery, Nashville, TN, USA
| | - Michael Cortelli
- Vanderbilt University Medical Center, Department of Cardiac Surgery, Nashville, TN, USA
| | - Carl A Johnson
- Vanderbilt University Medical Center, Department of Cardiac Surgery, Nashville, TN, USA
| | - Nancy Cardwell
- Vanderbilt University Medical Center, Department of Cardiac Surgery, Nashville, TN, USA
| | - Jennifer R Talackine
- Vanderbilt University Medical Center, Department of Cardiac Surgery, Nashville, TN, USA
| | - John W Stokes
- Vanderbilt University Medical Center, Department of Cardiac Surgery, Nashville, TN, USA
| | | | - Meredith Mentz
- Vanderbilt University Medical Center, Department of Cardiac Surgery, Nashville, TN, USA
| | - Kaitlyn M Tracy
- Vanderbilt University Medical Center, Department of Cardiac Surgery, Nashville, TN, USA
| | - Timothy R Harris
- Vanderbilt University Medical Center, Department of Cardiac Surgery, Nashville, TN, USA
| | - William Tucker
- Vanderbilt University Medical Center, Department of Cardiac Surgery, Nashville, TN, USA
| | | | - Caitlin T Demarest
- Vanderbilt University Medical Center, Department of Thoracic Surgery, Nashville, TN, USA
| | - Keith E Cook
- Carnegie Mellon University, Department of Biomedical Engineering, Pittsburgh, PA, USA
| | - David J Skoog
- Advanced Respiratory Technologies Inc, Pittsburgh, PA, USA
| | - Erika B Rosenzweig
- Columbia University Medical Center, Department of Pediatrics, New York NY, USA
| | - Matthew Bacchetta
- Vanderbilt University Medical Center, Department of Cardiac Surgery, Nashville, TN, USA; Vanderbilt University, Department of Biomedical Engineering, Nashville, TN, USA.
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Hima F, Kalverkamp S, Kashefi A, Mottaghy K, Zayat R, Strudthoff L, Spillner J, Mouzakis F. Oxygenation performance assessment of an artificial lung in different central anatomic configurations. Int J Artif Organs 2023; 46:295-302. [PMID: 37051677 PMCID: PMC10160396 DOI: 10.1177/03913988231168163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
Abstract
OBJECTIVES Aim of this work was to characterize possible central anatomical configurations in which a future artificial lung (AL) could be connected, in terms of oxygenation performance. METHODS Pulmonary and systemic circulations were simulated using a numerical and an in vitro approach. The in vitro simulation was carried out in a mock loop in three phases: (1) normal lung, (2) pulmonary shunt (50% and 100%), and (3) oxygenator support in three anatomical configurations: right atrium-pulmonary artery (RA-PA), pulmonary artery-left atrium (PA-LA), and aorta-left atrium (Ao-LA). The numerical simulation was performed for the oxygenator support phase. The oxygen saturation (SO2) of the arterial blood was plotted over time for two percentages of pulmonary shunt and three blood flow rates through the oxygenator. RESULTS During the pulmonary shunt phase, SO2 reached a steady state value (of 68% for a 50% shunt and of nearly 0% for a 100% shunt) 20 min after the shunt was set. During the oxygenator support phase, physiological values of SO2 were reached for RA-PA and PA-LA, in case of a 50% pulmonary shunt. For the same conditions, Ao-LA could reach a maximum SO2 of nearly 60%. Numerical results were congruous to the in vitro simulation ones. CONCLUSIONS Both in vitro and numerical simulations were able to properly characterize oxygenation properties of a future AL depending on its placement. Different anatomical configurations perform differently in terms of oxygenation. Right to right and right to left connections perform better than left to left ones.
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Affiliation(s)
- Flutura Hima
- Clinic for Thoracic Surgery, University Hospital RWTH Aachen, Aachen, Germany
| | | | - Ali Kashefi
- Institute of Physiology, RWTH Aachen University, Aachen, Germany
| | - Khosrow Mottaghy
- Institute of Physiology, RWTH Aachen University, Aachen, Germany
| | - Rachad Zayat
- Clinic for Thoracic Surgery, University Hospital RWTH Aachen, Aachen, Germany
| | - Lasse Strudthoff
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, RWTH Aachen University, Aachen, Germany
| | - Jan Spillner
- Clinic for Thoracic Surgery, University Hospital RWTH Aachen, Aachen, Germany
| | - Foivos Mouzakis
- Institute of Physiology, RWTH Aachen University, Aachen, Germany
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Chen Y, Li D, Liu Z, Liu Y, Fan H, Hou S. Research progress of portable extracorporeal membrane oxygenation. Expert Rev Med Devices 2023; 20:221-232. [PMID: 36846940 DOI: 10.1080/17434440.2023.2185136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
INTRODUCTION Extracorporeal membrane oxygenation (ECMO) is primarily used for the supportive treatment of patients suffering from severe cardiopulmonary failure. With the continued development of ECMO technology, the relevant scenarios also extend pre-hospital and inter-hospital. In order to meet the needs of emergency treatment in communities, disaster sites and battlefields, inter-hospital transfer and evacuation; miniaturized and portable ECMO has become a current research hotspot. AREA COVERED The paper first introduces the principle, composition and common modes of ECMO and summarizes the research status of portable ECMO, Novalung and wearable ECMO, analyzes the characteristics and shortcomings of existing equipment. finally, we discussed the focus and development trend of portable ECMO technology. EXPERT OPINION Currently, portable ECMO has many applications in interhospital transport and there are various studies on portable and wearable ECMO devices, but the development of portable ECMO still faces many challenges. In the future, research related to integrated components, rich sensor arrays, Intelligent ECMO system and lightweight technology can make future portable ECMO more suitable for pre-hospital emergency and interhospital transport.
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Affiliation(s)
- Yuansen Chen
- Institute of Disaster and Emergency Medicine, Tianjin University, Tianjin, China.,Wenzhou Safety (Emergency) Institute, Tianjin University, Wenzhou, China
| | - Duo Li
- Institute of Disaster and Emergency Medicine, Tianjin University, Tianjin, China.,Wenzhou Safety (Emergency) Institute, Tianjin University, Wenzhou, China
| | - Ziquan Liu
- Institute of Disaster and Emergency Medicine, Tianjin University, Tianjin, China.,Wenzhou Safety (Emergency) Institute, Tianjin University, Wenzhou, China
| | - Yanqing Liu
- Institute of Disaster and Emergency Medicine, Tianjin University, Tianjin, China.,Wenzhou Safety (Emergency) Institute, Tianjin University, Wenzhou, China
| | - Haojun Fan
- Institute of Disaster and Emergency Medicine, Tianjin University, Tianjin, China.,Wenzhou Safety (Emergency) Institute, Tianjin University, Wenzhou, China
| | - Shike Hou
- Institute of Disaster and Emergency Medicine, Tianjin University, Tianjin, China.,Wenzhou Safety (Emergency) Institute, Tianjin University, Wenzhou, China
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Fallon BP, Thompson AJ, Prater AR, Buchan S, Alberts T, Hoenerhoff M, Rojas-Pena A, Bartlett RH, Hirschl RB. Seven-day in vivo testing of a novel, low-resistance, pumpless pediatric artificial lung for long-term support. J Pediatr Surg 2022; 57:614-623. [PMID: 35953340 PMCID: PMC10112847 DOI: 10.1016/j.jpedsurg.2022.07.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 05/31/2022] [Accepted: 07/06/2022] [Indexed: 12/01/2022]
Abstract
INTRODUCTION For children with end-stage lung disease that cannot wean from extracorporeal life support (ECLS), a wearable artificial lung would permit extubation and provide a bridge to recovery or transplantation. We evaluate the function of the novel Pediatric MLung-a low-resistance, pumpless artificial lung developed specifically for children-in healthy animal subjects. METHODS Adolescent "mini sheep" weighing 12-20 kg underwent left thoracotomy, cannulation of the main pulmonary artery (PA; inflow) and left atrium (outflow), and connection to the MLung. RESULTS Thirteen sheep were studied; 6 were supported for 7 days. Mean PA pressure was 23.9 ± 6.9 mmHg. MLung blood flow was 633±258 mL/min or 30.0 ± 16.0% of CO. MLung pressure drop was 4.4 ± 3.4 mmHg. Resistance was 7.2 ± 5.2 mmHg/L/min. Device outlet oxygen saturation was 99.0 ± 3.3% with inlet saturation 53.8 ± 7.3%. Oxygen delivery was 41.1 ± 18.4 mL O2/min (maximum 84.9 mL/min) or 2.8 ± 1.5 mL O2/min/kg. Platelet count significantly decreased; no platelet transfusions were required. Plasma free hemoglobin significantly increased only on day 7, at which point 2 of the animals had plasma free hemoglobin levels above 50 mg/dL. CONCLUSION The MLung provides adequate gas exchange at appropriate blood flows for the pediatric population in a PA-to-LA configuration. Further work remains to improve the biocompatibility of the device. LEVEL OF EVIDENCE N/A.
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Affiliation(s)
- Brian P Fallon
- Department of Surgery, Extracorporeal Life Support Laboratory, Michigan Medicine, B560 MSRB II/SPC 5686, 1150 W. Medical Center Drive, Ann Arbor, MI 48109, USA.
| | - Alex J Thompson
- Department of Surgery, Extracorporeal Life Support Laboratory, Michigan Medicine, B560 MSRB II/SPC 5686, 1150 W. Medical Center Drive, Ann Arbor, MI 48109, USA
| | - Aaron R Prater
- Department of Surgery, Extracorporeal Life Support Laboratory, Michigan Medicine, B560 MSRB II/SPC 5686, 1150 W. Medical Center Drive, Ann Arbor, MI 48109, USA
| | - Skylar Buchan
- Department of Surgery, Extracorporeal Life Support Laboratory, Michigan Medicine, B560 MSRB II/SPC 5686, 1150 W. Medical Center Drive, Ann Arbor, MI 48109, USA
| | - Trevor Alberts
- Department of Surgery, Extracorporeal Life Support Laboratory, Michigan Medicine, B560 MSRB II/SPC 5686, 1150 W. Medical Center Drive, Ann Arbor, MI 48109, USA
| | - Mark Hoenerhoff
- In Vivo Animal Core, Unit for Laboratory Animal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Alvaro Rojas-Pena
- Department of Surgery, Extracorporeal Life Support Laboratory, Michigan Medicine, B560 MSRB II/SPC 5686, 1150 W. Medical Center Drive, Ann Arbor, MI 48109, USA; Department of Surgery, Section of Transplant Surgery, Michigan Medicine, Ann Arbor, MI, USA
| | - Robert H Bartlett
- Department of Surgery, Extracorporeal Life Support Laboratory, Michigan Medicine, B560 MSRB II/SPC 5686, 1150 W. Medical Center Drive, Ann Arbor, MI 48109, USA
| | - Ronald B Hirschl
- Department of Surgery, Extracorporeal Life Support Laboratory, Michigan Medicine, B560 MSRB II/SPC 5686, 1150 W. Medical Center Drive, Ann Arbor, MI 48109, USA; Department of Surgery, Section of Pediatric Surgery, Michigan Medicine, Ann Arbor, MI, USA
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Hemocompatibility challenge of membrane oxygenator for artificial lung technology. Acta Biomater 2022; 152:19-46. [PMID: 36089235 DOI: 10.1016/j.actbio.2022.09.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 08/25/2022] [Accepted: 09/04/2022] [Indexed: 11/24/2022]
Abstract
The artificial lung (AL) technology is one of the membrane-based artificial organs that partly augments lung functions, i.e. blood oxygenation and CO2 removal. It is generally employed as an extracorporeal membrane oxygenation (ECMO) device to treat acute and chronic lung-failure patients, and the recent outbreak of the COVID-19 pandemic has re-emphasized the importance of this technology. The principal component in AL is the polymeric membrane oxygenator that facilitates the O2/CO2 exchange with the blood. Despite the considerable improvement in anti-thrombogenic biomaterials in other applications (e.g., stents), AL research has not advanced at the same rate. This is partly because AL research requires interdisciplinary knowledge in biomaterials and membrane technology. Some of the promising biomaterials with reasonable hemocompatibility - such as emerging fluoropolymers of extremely low surface energy - must first be fabricated into membranes to exhibit effective gas exchange performance. As AL membranes must also demonstrate high hemocompatibility in tandem, it is essential to test the membranes using in-vitro hemocompatibility experiments before in-vivo test. Hence, it is vital to have a reliable in-vitro experimental protocol that can be reasonably correlated with the in-vivo results. However, current in-vitro AL studies are unsystematic to allow a consistent comparison with in-vivo results. More specifically, current literature on AL biomaterial in-vitro hemocompatibility data are not quantitatively comparable due to the use of unstandardized and unreliable protocols. Such a wide gap has been the main bottleneck in the improvement of AL research, preventing promising biomaterials from reaching clinical trials. This review summarizes the current state-of-the-art and status of AL technology from membrane researcher perspectives. Particularly, most of the reported in-vitro experiments to assess AL membrane hemocompatibility are compiled and critically compared to suggest the most reliable method suitable for AL biomaterial research. Also, a brief review of current approaches to improve AL hemocompatibility is summarized. STATEMENT OF SIGNIFICANCE: The importance of Artificial Lung (AL) technology has been re-emphasized in the time of the COVID-19 pandemic. The utmost bottleneck in the current AL technology is the poor hemocompatibility of the polymer membrane used for O2/CO2 gas exchange, limiting its use in the long-term. Unfortunately, most of the in-vitro AL experiments are unsystematic, irreproducible, and unreliable. There are no standardized in-vitro hemocompatibility characterization protocols for quantitative comparison between AL biomaterials. In this review, we tackled this bottleneck by compiling the scattered in-vitro data and suggesting the most suitable experimental protocol to obtain reliable and comparable hemocompatibility results. To the best of our knowledge, this is the first review paper focusing on the hemocompatibility challenge of AL technology.
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Patterson CM, Shah A, Rabin J, DiChiacchio L, Cypel M, Hoetzenecker K, Catarino P, Lau CL. EXTRACORPOREAL LIFE SUPPORT AS A BRIDGE TO LUNG TRANSPLANTATION: WHERE ARE WE NOW? J Heart Lung Transplant 2022; 41:1547-1555. [DOI: 10.1016/j.healun.2022.06.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 04/21/2022] [Accepted: 06/05/2022] [Indexed: 11/16/2022] Open
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In Vitro and In Vivo Feasibility Study for a Portable VV-ECMO and ECCO2R System. MEMBRANES 2022; 12:membranes12020133. [PMID: 35207055 PMCID: PMC8875538 DOI: 10.3390/membranes12020133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 01/11/2022] [Accepted: 01/18/2022] [Indexed: 11/17/2022]
Abstract
Extracorporeal membrane oxygenation (ECMO) is an established rescue therapy for patients with chronic respiratory failure waiting for lung transplantation (LTx). The therapy inherent immobilization may result in fatigue, consecutive deteriorated prognosis, and even lost eligibility for transplantation. We conducted a feasibility study on a novel system designed for the deployment of a portable ECMO device, enabling the physical exercise of awake patients prior to LTx. The system comprises a novel oxygenator with a directly connected blood pump, a double-lumen cannula, gas blender and supply, as well as control and energy management. In vitro experiments included tests regarding performance, efficiency, and blood damage. A reduced system was tested in vivo for feasibility using a novel large animal model. Six anesthetized pigs were first positioned in supine position, followed by a 45° angle, simulating an upright position of the patients. We monitored performance and vital parameters. All in vitro experiments showed good performance for the respective subsystems and the integrated system. The acute in vivo trials of 8 h duration confirmed the results. The novel portable ECMO-system enables adequate oxygenation and decarboxylation sufficient for, e.g., the physical exercise of designated LTx-recipients. These results are promising and suggest further preclinical studies on safety and efficacy to facilitate translation into clinical application.
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Polastri M, Loforte A, Dell'Amore A, Swol J. Physiotherapy and artificial lungs: looking to the future. INTERNATIONAL JOURNAL OF THERAPY AND REHABILITATION 2021. [DOI: 10.12968/ijtr.2021.0103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Massimiliano Polastri
- Department of Continuity of Care and Disability, Physical Medicine and Rehabilitation, St Orsola University Hospital, Bologna, Italy
- Critical and Respiratory Care Unit, University Hospital of Bologna, Scientific Institute for Research, Hospitalization and Healthcare, Bologna, Italy
| | - Antonio Loforte
- Division of Cardiac Surgery, University Hospital of Bologna, Scientific Institute for Research, Hospitalization and Healthcare, Bologna, Italy
| | | | - Justyna Swol
- Department of Respiratory Medicine, Allergology and Sleep Medicine, Paracelsus Medical University General Hospital, Nuremberg, Germany
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Orizondo RA, Omecinski KS, May AG, Dhamotharan V, Frankowski BJ, Burgreen GW, Ye SH, Kocyildirim E, Sanchez PG, D’Cunha J, Wagner WR, Federspiel WJ. Month-long Respiratory Support by a Wearable Pumping Artificial Lung in an Ovine Model. Transplantation 2021; 105:999-1007. [PMID: 33031226 PMCID: PMC8024407 DOI: 10.1097/tp.0000000000003481] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND A wearable artificial lung could improve lung transplantation outcomes by easing implementation of physical rehabilitation during long-term pretransplant respiratory support. The Modular Extracorporeal Lung Assist System (ModELAS) is a compact pumping artificial lung currently under development. This study evaluated the long-term in vivo performance of the ModELAS during venovenous support in awake sheep. Feedback from early trials and computational fluid dynamic analysis guided device design optimization along the way. METHODS The ModELAS was connected to healthy sheep via a dual-lumen cannula in the jugular vein. Sheep were housed in a fixed-tether pen while wearing the device in a holster during support. Targeted blood flow rate and support duration were 2-2.5 L/min and 28-30 days, respectively. Anticoagulation was maintained via systemic heparin. Device pumping and gas exchange performance and hematologic indicators of sheep physiology were measured throughout support. RESULTS Computational fluid dynamic-guided design modifications successfully decreased pump thrombogenicity from initial designs. For the optimized design, 4 of 5 trials advancing past early perioperative and cannula-related complications lasted the full month of support. Blood flow rate and CO2 removal in these trials were 2.1 ± 0.3 L/min and 139 ± 15 mL/min, respectively, and were stable during support. One trial ended after 22 days of support due to intradevice thrombosis. Support was well tolerated by the sheep with no signs of hemolysis or device-related organ impairment. CONCLUSIONS These results demonstrate the ability of the ModELAS to provide safe month-long support without consistent deterioration of pumping or gas exchange capabilities.
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Affiliation(s)
- Ryan A. Orizondo
- McGowan Institute for Regenerative Medicine, University of Pittsburgh
- Department of Medicine, University of Pittsburgh
- Department of Bioengineering, University of Pittsburgh
| | - Katelin S. Omecinski
- McGowan Institute for Regenerative Medicine, University of Pittsburgh
- Department of Bioengineering, University of Pittsburgh
| | - Alexandra G. May
- McGowan Institute for Regenerative Medicine, University of Pittsburgh
- Department of Chemical and Petroleum Engineering, University of Pittsburgh
| | - Vishaal Dhamotharan
- McGowan Institute for Regenerative Medicine, University of Pittsburgh
- Department of Bioengineering, University of Pittsburgh
| | | | - Greg W. Burgreen
- Computational Fluid Dynamics Group, Center for Advanced Vehicular Systems, Mississippi State University
| | - Sang-Ho Ye
- McGowan Institute for Regenerative Medicine, University of Pittsburgh
- Department of Surgery, University of Pittsburgh
| | - Ergin Kocyildirim
- McGowan Institute for Regenerative Medicine, University of Pittsburgh
- Department of Cardiothoracic Surgery, Children’s Hospital of Pittsburgh
| | - Pablo G. Sanchez
- Department of Cardiothoracic Surgery, University of Pittsburgh Medical Center
| | - Jonathan D’Cunha
- Department of Cardiothoracic Surgery, University of Pittsburgh Medical Center
| | - William R. Wagner
- McGowan Institute for Regenerative Medicine, University of Pittsburgh
- Department of Bioengineering, University of Pittsburgh
- Department of Chemical and Petroleum Engineering, University of Pittsburgh
- Department of Surgery, University of Pittsburgh
| | - William J. Federspiel
- McGowan Institute for Regenerative Medicine, University of Pittsburgh
- Department of Bioengineering, University of Pittsburgh
- Department of Chemical and Petroleum Engineering, University of Pittsburgh
- Department of Critical Care Medicine, University of Pittsburgh Medical Center
- Clinical and Translational Science Institute, University of Pittsburgh
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12
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Duy Nguyen BT, Nguyen Thi HY, Nguyen Thi BP, Kang DK, Kim JF. The Roles of Membrane Technology in Artificial Organs: Current Challenges and Perspectives. MEMBRANES 2021; 11:239. [PMID: 33800659 PMCID: PMC8065507 DOI: 10.3390/membranes11040239] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 03/20/2021] [Accepted: 03/20/2021] [Indexed: 02/07/2023]
Abstract
The recent outbreak of the COVID-19 pandemic in 2020 reasserted the necessity of artificial lung membrane technology to treat patients with acute lung failure. In addition, the aging world population inevitably leads to higher demand for better artificial organ (AO) devices. Membrane technology is the central component in many of the AO devices including lung, kidney, liver and pancreas. Although AO technology has improved significantly in the past few decades, the quality of life of organ failure patients is still poor and the technology must be improved further. Most of the current AO literature focuses on the treatment and the clinical use of AO, while the research on the membrane development aspect of AO is relatively scarce. One of the speculated reasons is the wide interdisciplinary spectrum of AO technology, ranging from biotechnology to polymer chemistry and process engineering. In this review, in order to facilitate the membrane aspects of the AO research, the roles of membrane technology in the AO devices, along with the current challenges, are summarized. This review shows that there is a clear need for better membranes in terms of biocompatibility, permselectivity, module design, and process configuration.
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Affiliation(s)
- Bao Tran Duy Nguyen
- Department of Energy and Chemical Engineering, Incheon National University, Incheon 22012, Korea; (B.T.D.N.); (H.Y.N.T.); (B.P.N.T.)
| | - Hai Yen Nguyen Thi
- Department of Energy and Chemical Engineering, Incheon National University, Incheon 22012, Korea; (B.T.D.N.); (H.Y.N.T.); (B.P.N.T.)
| | - Bich Phuong Nguyen Thi
- Department of Energy and Chemical Engineering, Incheon National University, Incheon 22012, Korea; (B.T.D.N.); (H.Y.N.T.); (B.P.N.T.)
| | - Dong-Ku Kang
- Department of Chemistry, Incheon National University, Incheon 22012, Korea
| | - Jeong F. Kim
- Department of Energy and Chemical Engineering, Incheon National University, Incheon 22012, Korea; (B.T.D.N.); (H.Y.N.T.); (B.P.N.T.)
- Innovation Center for Chemical Engineering, Incheon National University, Incheon 22012, Korea
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13
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Blauvelt DG, Abada EN, Oishi P, Roy S. Advances in extracorporeal membrane oxygenator design for artificial placenta technology. Artif Organs 2021; 45:205-221. [PMID: 32979857 PMCID: PMC8513573 DOI: 10.1111/aor.13827] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 07/28/2020] [Accepted: 09/10/2020] [Indexed: 12/15/2022]
Abstract
Extreme prematurity, defined as a gestational age of fewer than 28 weeks, is a significant health problem worldwide. It carries a high burden of mortality and morbidity, in large part due to the immaturity of the lungs at this stage of development. The standard of care for these patients includes support with mechanical ventilation, which exacerbates lung pathology. Extracorporeal life support (ECLS), also called artificial placenta technology when applied to extremely preterm (EPT) infants, offers an intriguing solution. ECLS involves providing gas exchange via an extracorporeal device, thereby doing the work of the lungs and allowing them to develop without being subjected to injurious mechanical ventilation. While ECLS has been successfully used in respiratory failure in full-term neonates, children, and adults, it has not been applied effectively to the EPT patient population. In this review, we discuss the unique aspects of EPT infants and the challenges of applying ECLS to these patients. In addition, we review recent progress in artificial placenta technology development. We then offer analysis on design considerations for successful engineering of a membrane oxygenator for an artificial placenta circuit. Finally, we examine next-generation oxygenators that might advance the development of artificial placenta devices.
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Affiliation(s)
- David G. Blauvelt
- Department of Pediatrics, University of California, San Francisco, California
| | - Emily N. Abada
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, California
| | - Peter Oishi
- Department of Pediatrics, University of California, San Francisco, California
| | - Shuvo Roy
- Department of Pediatrics, University of California, San Francisco, California
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Abstract
The use of extracorporeal life support (ECLS) for the pediatric and neonatal population continues to grow. At the same time, there have been dramatic improvements in the technology and safety of ECLS that have broadened the scope of its application. This article will review the evolving landscape of ECLS, including its expanding indications and shrinking contraindications. It will also describe traditional and hybrid cannulation strategies as well as changes in circuit components such as servo regulation, non-thrombogenic surfaces, and paracorporeal lung-assist devices. Finally, it will outline the modern approach to managing a patient on ECLS, including anticoagulation, sedation, rehabilitation, nutrition, and staffing.
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May AG, Orizondo RA, Frankowski BJ, Ye SH, Kocyildirim E, Wagner WR, D'Cunha J, Federspiel WJ. In vivo testing of the low-flow CO 2 removal application of a compact, platform respiratory device. Intensive Care Med Exp 2020; 8:45. [PMID: 32804310 PMCID: PMC7429452 DOI: 10.1186/s40635-020-00329-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 07/16/2020] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Non-invasive and lung-protective ventilation techniques may improve outcomes for patients with an acute exacerbation of chronic obstructive pulmonary disease or moderate acute respiratory distress syndrome by reducing airway pressures. These less invasive techniques can fail due to hypercapnia and require transitioning patients to invasive mechanical ventilation. Extracorporeal CO2 removal devices remove CO2 independent of the lungs thereby controlling the hypercapnia and permitting non-invasive or lung-protective ventilation techniques. We are developing the Modular Extracorporeal Lung Assist System as a platform technology capable of providing three levels of respiratory assist: adult and pediatric full respiratory support and adult low-flow CO2 removal. The objective of this study was to evaluate the in vivo performance of our device to achieve low-flow CO2 removal. METHODS The Modular Extracorporeal Lung Assist System was connected to 6 healthy sheep via a 15.5 Fr dual-lumen catheter placed in the external jugular vein. The animals were recovered and tethered within a pen while supported by the device for 7 days. The pump speed was set to achieve a targeted blood flow of 500 mL/min. The extracorporeal CO2 removal rate was measured daily at a sweep gas independent regime. Hematological parameters were measured pre-operatively and regularly throughout the study. Histopathological samples of the end organs were taken at the end of each study. RESULTS All animals survived the surgery and generally tolerated the device well. One animal required early termination due to a pulmonary embolism. Intra-device thrombus formation occurred in a single animal due to improper anticoagulation. The average CO2 removal rate (normalized to an inlet pCO2 of 45 mmHg) was 75.6 ± 4.7 mL/min and did not significantly change over the course of the study (p > 0.05). No signs of consistent hemolysis or end organ damage were observed. CONCLUSION These in vivo results indicate positive performance of the Modular Extracorporeal Lung Assist System as a low-flow CO2 removal device.
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Affiliation(s)
- Alexandra G May
- Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, 3025 East Carson Street, Pittsburgh, PA, 15203, USA
| | - Ryan A Orizondo
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, 3025 East Carson Street, Pittsburgh, PA, 15203, USA
- Department of Medicine, University of Pittsburgh, Pittsburgh, USA
| | - Brian J Frankowski
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, 3025 East Carson Street, Pittsburgh, PA, 15203, USA
| | - Sang-Ho Ye
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, 3025 East Carson Street, Pittsburgh, PA, 15203, USA
- Department of Surgery, University of Pittsburgh, Pittsburgh, USA
| | - Ergin Kocyildirim
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, 3025 East Carson Street, Pittsburgh, PA, 15203, USA
- Department of Cardiothoracic Surgery, Children's Hospital of Pittsburgh, Pittsburgh, USA
| | - William R Wagner
- Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, 3025 East Carson Street, Pittsburgh, PA, 15203, USA
- Department of Surgery, University of Pittsburgh, Pittsburgh, USA
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, USA
| | - Jonathan D'Cunha
- Division of Lung Transplantation/Lung Failure, Department of Cardiothoracic Surgery, University of Pittsburgh Medical Center, Pittsburgh, USA
| | - William J Federspiel
- Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, USA.
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, 3025 East Carson Street, Pittsburgh, PA, 15203, USA.
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, USA.
- Department of Critical Care Medicine, University of Pittsburgh Medical Center, Pittsburgh, USA.
- Clinical and Translational Science Institute, University of Pittsburgh, Pittsburgh, USA.
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Rinaudo A, Pasta S. Development of a self-pumping extracorporeal blood oxygenation device characterized by a rotating shaft with embedded fiber packages. Int J Artif Organs 2020; 43:393-400. [DOI: 10.1177/0391398819893380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Introduction: To offer respiratory support for patients with lung disease, a novel technological solution for blood pumping and oxygenation is being developed. The pump–lung system was designed to integrate fiber membranes into six packages radially embedded in a rotating hollow shaft placed along the longitudinal axis of the device. Fiber packages are inclined with respect to the rotation axis so that the rotational motion of the rotating shaft allows a self-pumping system to be obtained. Method: Both hemodynamic and gas transfer performances were investigated using both in vitro experiments and in silico flow analyses. Results: The predicted flow velocity in the pump chamber was smooth and characterized by high peripheral velocities near the housing wall. As the blood flow enters the inlet, the static pressure increased with the angular momentum imparted to the fiber packages. Experiments confirmed that the proposed pump–lung system can provide adequate blood flow and oxygen transfer over the range of intended operating conditions (0.5–5 L/min and 500–1500 r/min). Conclusion: Although the study did not include animal testing, the novel pump-oxygenator solution is feasible for respiratory support in patients with lung diseases.
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Affiliation(s)
- Antonino Rinaudo
- Department of Engineering, Università degli Studi di Palermo, Palermo, Italy
| | - Salvatore Pasta
- Department of Engineering, Università degli Studi di Palermo, Palermo, Italy
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Steuer NB, Hugenroth K, Beck T, Spillner J, Kopp R, Reinartz S, Schmitz-Rode T, Steinseifer U, Wagner G, Arens J. Long-Term Venovenous Connection for Extracorporeal Carbon Dioxide Removal (ECCO 2R)-Numerical Investigation of the Connection to the Common Iliac Veins. Cardiovasc Eng Technol 2020; 11:362-380. [PMID: 32405926 PMCID: PMC7385029 DOI: 10.1007/s13239-020-00466-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 05/02/2020] [Indexed: 02/06/2023]
Abstract
Purpose Currently used cannulae for extracorporeal carbon dioxide removal (ECCO2R) are associated with complications such as thrombosis and distal limb ischemia, especially for long-term use. We hypothesize that the risk of these complications is reducible by attaching hemodynamically optimized grafts to the patient’s vessels. In this study, as a first step towards a long-term stable ECCO2R connection, we investigated the feasibility of a venovenous connection to the common iliac veins. To ensure its applicability, the drainage of reinfused blood (recirculation) and high wall shear stress (WSS) must be avoided. Methods A reference model was selected for computational fluid dynamics, on the basis of the analysis of imaging data. Initially, a sensitivity analysis regarding recirculation was conducted using as variables: blood flow, the distance of drainage and return to the iliocaval junction, as well as the diameter and position of the grafts. Subsequently, the connection was optimized regarding recirculation and the WSS was evaluated. We validated the simulations in a silicone model traversed by dyed fluid. Results The simulations were in good agreement with the validation measurements (mean deviation 1.64%). The recirculation ranged from 32.1 to 0%. The maximum WSS did not exceed 5.57 Pa. The position and diameter of the return graft show the highest influence on recirculation. A correlation was ascertained between recirculation and WSS. Overall, an inflow jet directed at a vessel wall entails not only high WSS, but also a flow separation and thereby an increased recirculation. Therefore, return grafts aligned to the vena cava are crucial. Conclusion In conclusion, a connection without recirculation could be feasible and therefore provides a promising option for a long-term ECCO2R connection.
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Affiliation(s)
- N B Steuer
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Medical Faculty, RWTH Aachen University, Aachen, Germany.
| | - K Hugenroth
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - T Beck
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - J Spillner
- Clinic for Cardiothoracic Surgery, University Hospital RWTH Aachen, Aachen, Germany
| | - R Kopp
- Department of Anesthesiology, University Hospital RWTH Aachen, Aachen, Germany
| | - S Reinartz
- Department of Radiology, University Hospital RWTH Aachen, Aachen, Germany
| | - T Schmitz-Rode
- Institute of Applied Medical Engineering, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - U Steinseifer
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - G Wagner
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - J Arens
- Department of Cardiovascular Engineering, Institute of Applied Medical Engineering, Medical Faculty, RWTH Aachen University, Aachen, Germany.,Chair in Engineering Organ Support Technologies, Department of Biomechanical Engineering, Faculty of Engineering Technologies, University of Twente, Enschede, The Netherlands
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19
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Conway RG, Berk ZB, Zhang J, Li T, Tran D, Wu ZJ, Griffith BP. Evaluation of an autoregulatory ECMO system for total respiratory support in an acute ovine model. Artif Organs 2020; 44:478-487. [PMID: 31854002 PMCID: PMC7165054 DOI: 10.1111/aor.13618] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 11/19/2019] [Accepted: 12/12/2019] [Indexed: 11/29/2022]
Abstract
Extracorporeal membrane oxygenation (ECMO) has become a mainstay of therapy for patients suffering from severe respiratory failure. Ambulatory ECMO systems aim to provide long-term out-of-hospital respiratory support. As a patient's activity level changes, the required level of ECMO support varies with oxygen consumption and metabolic fluctuations. To compensate for such changes, an autoregulatory ECMO system (AR-ECMO) has been developed and its performance was evaluated as a proof of concept in an acute ovine model. The AR-ECMO system consists of a regular ECMO circuit and an electromechanical control system. A custom fuzzy logic control algorithm was implemented to adjust the blood flow and sweep gas flow of the ECMO circuit to meet the varying respiratory demand by utilizing two noninvasive sensors for venous oxyhemoglobin saturation and the oxygenator exhaust gas CO2 concentration. Disturbance responses of the AR-ECMO to induced acute respiratory distress were assessed for six hours in four juvenile sheep cannulated with a veno-pulmonary artery ECMO configuration, including acute ventilator shutoff, ventilator step change (off-on-off), and forced desaturation. All sheep survived for the study duration. The AR-ECMO system was able to respond and maintain stable hemodynamics and physiological blood gas contents (SpO2 = 96.3 % ± 4.29, pH 7.44 ± 0.09, pCO2 = 38.9 ± 9.9 mm Hg, and pO2 =237.9 ± 123.6 mm Hg) during simulated respiratory distress. Acceptable correlation between oxygenator exhaust gas CO2 and oxygenator outlet pCO2 were observed (R2 = 0.84). In summary, the AR-ECMO system successfully maintained physiologic control of peripheral oxygenation and carbon dioxide over the study period, utilizing only measurements taken directly from the ECMO circuit. The range of system response necessitates an adaptable system in the setting of variable metabolic demands. The ability of this system to respond to significant disturbances in ventilator support is encouraging. Future work to evaluate our AR-ECMO system in long-term, awake animal studies is necessary for further refinement.
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Affiliation(s)
- Robert G. Conway
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Zachary B Berk
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Jiafeng Zhang
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Tieluo Li
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Douglas Tran
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Zhongjun J. Wu
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
- Fischell Department of Bioengineering, A. James Clark School of Engineering, University of Maryland, College Park, MD 20742, USA
| | - Bartley P. Griffith
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
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