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Original Articles: General Thoracic

Invited Commentary

Experimental ECMO Laboratory and Department of Surgery, University of Kentucky, Chandler Medical Center, 800 Rose St, Lexington, KY 40536

(Email: jzwis2{at}email.uky.edu).

In this issue of The Annals of Thoracic Surgery, Akay and colleagues [1] describe their growing experience with the paracorporeal transthoracic in parallel (pulmonary artery [PA] to left atrium [LA]) artificial lung in sheep. The team at the University of Michigan utilized infusions of dobutamine at 0, 2, and 5 mcg/kg/min as a surrogate for exercise in sheep with and without pulmonary hypertension. This was coupled with progressive banding of the pulmonary artery to divert progressively more bloodflow through the artificial lung circuit until 90% of the cardiac output was diverted. The effects on right ventricular strain and other hemodynamic measurements were measured. Mild hemodynamic compromise with increased right ventricular strain was observed at the highest blood flows and at the highest dobutamine concentration. At levels consistent with mild exercise, however, the artificial lung was well tolerated.

The paracorporeal transthoracic artificial lung in parallel with the native lung is a configuration pioneered by the group in Michigan. This offers the benefits of a single heart driven PA-LA shunt without the need for a separate blood pump, and this creates less right heart strain than previous pumpless configurations. However, drawbacks include two major sites of access and a delicate anastamosis, risk of thrombus or air embolism, and a variable amount of flow through the device depending on resistance in the pulmonary circuit. Other configurations of the artificial lung currently in various stages of development include right atrium to LA [2], right atrium to PA [3], and limited ambulatory venovenous extracorporeal membrane oxygenation [4]. Although these three configurations all require a pump as well as a gas exchanger, they do not strain the right heart, they have predictable flow, and they can still allow for ambulation and rehabilitation. Notably, limited venovenous extracorporeal membrane oxygenation through a new double-lumen cannula served as the first practical ambulatory bridge to transplant [5].

Addressing such practical issues as exercise in artificial lung experiments signals that we are entering a new era of artificial lung development and testing. Although much remains unsettled regarding the final design, configuration, and mode of attachment, this study demonstrates that it is no longer acceptable to just attach an artificial lung to a normal animal and have that animal survive a few hours. Practical questions regarding ambulation, rehabilitation, and quality of life are as important a metric as blood flow, resistance, or cardiac output, and all will directly impact the application of the artificial lung as a bridge to recovery, transplantation, or destination therapy.

	References

Top References

 

1. Akay B, Reoma JL, Camboni D, et al. In-parallel artificial lung attachment at high flows in normal and pulmonary hypertension models Ann Thorac Surg 2010;90:259-265.[Abstract/Free Full Text]
2. Zhang T, Cheng G, Koert A, et al. Artif Organs. Functional and biocompatibility performances of an integrated Maglev pump-oxygenator. Artificial Organs 2009;33:36-45.[Medline]
3. Wang D, Lick SD, Zhou X, Liu X, Benkowski RJ, Zwischenberger JB. Ambulatory oxygenator right ventricular assist device for total right heart and respiratory support Ann Thorac Surg 2007;84:1699-1703.[Abstract/Free Full Text]
4. Wang D, Zhou X, Liu X, Sidor B, Lynch J, Zwischenberger JB. Wang-Zwische double lumen cannula-toward a percutaneous and ambulatory paracorporeal artificial lung ASAIO J 2008;54:606-611.[Medline]
5. Garcia JP, Iacono A, Kon ZN, Griffith BP. Ambulatory extracorporeal membrane oxygenation: A new approach for bridge-to-lung transplantation Thorac Cardiovasc Surg 2010(e-pub ahead of print).

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Joseph B. Zwischenberger Permission Requests Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Lynch, J. E. Articles by Zwischenberger, J. B. Search for Related Content PubMed PubMed Citation Articles by Lynch, J. E. Articles by Zwischenberger, J. B. Related Collections Lung - other Extracorporeal circulation Related Article