Principles Of Lung Preservation

Optimal lung preservation requires limiting lung injury. It is dependent not only upon the procurement, perfusion, and ventilation techniques, but also upon the initial management of reperfusion and ventilation following implant.

Lung injury that occurs following restoration of blood flow during transplantation is called the ischemia-reperfusion injury, or reimplantation response. Organ dysfunction from reperfusion injury is characterized by impaired gas exchange, decreased compliance, interstitial and alveolar edema (due in part to increased vascular permeability), and death. Ischemia-reperfusion injury may also predispose grafts to early rejection via upregulation of class II major histocompatibility complex antigens or through local production of cytokines.3 Lung preservation is unique from other organ preservation techniques due to the following factors: 1) the lung has a large alveolar-capillary surface area created from approximately 300 million delicate alveolar units; 2) the lung has a blood gas interface; 3) the lung has a dual blood supply (pulmonary arterial and bronchial arterial); and 4) the inflated lung has a ready oxygen source during the ischemic transport phase (alveolar gas).

Preservation techniques have focused on modifications of antegrade and retrograde vascular perfusion as well as ventilation. Given the high incidence of acute rejection observed following lung transplantation (compared to cardiac transplantation) and the role ischemia-reperfusion injury plays in acute organ rejection, adequate preservation is paramount to successful immediate and long term graft function.

Single flush perfusion followed by static hypothermic storage has emerged as the standard procurement technique. Cardiopulmonary bypass with profound hypothermia (donor-core cooling) is a labor-intensive technique, which found great success by Yacoub et al at Harefield and Reitz and Baumgartner at the Johns Hopkins Baltimore Transplant Center.4,5 Topical cooling after absorption atelectasis, which was the method used for the first long-term successful lung transplant in 1981, is no longer used today. Hardesty and Griffith at Pittsburgh utilized normo-thermic autoperfusion of the heart-lung block and achieved early successful results; this is rarely used and of historical interest only.

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