immunology allergic disorders
Lung and Heart Lung Transplantation
Procedure
The donor is anticoagulated, and a cold crystalloid preservation solution containing prostaglandins is flushed through the pulmonary arteries into the lungs. Donor organs are cooled with iced saline slush in situ or via cardiopulmonary bypass, then removed. Prophylactic antibiotics are often given. Single lung transplantation requires posterolateral thoracotomy. The native lung is removed, and the bronchus, pulmonary artery, and pulmonary veins of the donor lung are anastomosed to their respective cuffs. The bronchial anastomosis requires intussusception or wrapping with omentum or pericardium to facilitate adequate healing. Advantagesof single lung transplantation include a simpler operation, avoidance of cardiopulmonary bypass and systemic anticoagulation (usually), more flexibility concerning size matching, and availability of the contralateral lung from the same donor for another recipient. Disadvantagesinclude the possibility of ventilation/perfusion mismatch between the native and transplant lungs and the possibility of poor healing of the single bronchial anastomosis. Double lung transplantation requires sternotomy or anterior transverse thoracotomy; the procedure is similar to 2 sequential single transplants. Theprimary advantageis definitive removal of all diseased lung tissue in the recipient. Thedisadvantageis poor healing of the tracheal anastomosis. Heart-lung transplantation requires median sternotomy with cardiopulmonary bypass. Aortic, right atrial, and tracheal anastomoses are required; the trachea is anastomosed immediately above the bifurcation. Theprimary advantagesare improved graft function and more dependable healing of the tracheal anastomosis because of coronary-bronchial collaterals within the heart-lung block. Disadvantagesinclude long operative time with the need for cardiopulmonary bypass, the need for close size matching, and use of 3 donor organs by one recipient. A common 3-drug Posttransplantation Immunosuppression regimen combines A calcineurin inhibitor (cyclosporineortacrolimus) A purine metabolism inhibitor (azathioprineormycophenolate) Methylprednisoloneor another corticosteroid IV is often given intraoperatively before reperfusion of the transplanted lung. Lower doses are given for maintenance thereafter (see table Immunosuppressants Used to Treat Transplant Rejection ). Antithymocyte globulin(ATG) oralemtuzumabis often given as induction therapy. These drugs can also minimize immunosuppressive therapy posttransplantation. Often,tacrolimusmonotherapy is sufficient for maintenance therapy if induction therapy is given. Corticosteroids may be omitted to facilitate healing of the bronchial anastomosis; higher doses of other drugs (eg,cyclosporine,azathioprine) are then used instead. Immunosuppressants are continued indefinitely. 