A MODEL OF UNILATERAL PULMONARY LOBAR TRANSPLANTATION

Unilateral lung transplantation has become an accepted treatment for p atients with end-stage pulmonary disease. Donor shortage, however, is a major limitation, with up to 87% of patients dying of their pulmonar y disease while awaiting transplantation. This is especially true in n eonatal and pediatric patient populations. The use of organ segments f rom cadaveric or living donors may provide a solution. The purpose of this study, therefore, was to evaluate the function and hemodynamic re sponse to pulmonary lobar transplantation using a swine model. Five tr ansplants were performed for acute study, while 10 were performed for 6-week survival. The left lower lobe was harvested from a 70- to 75-kg donor animal. The lobe was then transplanted into a 20 to 25-kg recip ient following left pneumonectomy. Graft function was determined by pu lmonary arterial and venous blood gas analysis. Cardiac output, pulmon ary pressure, and pulmonary vascular resistance were measured under tw o experimental conditions: (1) baseline and (2) with the right pulmona ry artery occluded, forcing the entire cardiac output through the loba r graft. All grafts showed excellent acute and long-term function with regard to gas exchange. The lobar grafts, however, were characterized by high pulmonary vascular resistance both acutely and 6 weeks post-t ransplant. Contralateral pulmonary artery occlusion resulted in hemody namic instability and right heart failure. No animal was able to be so lely supported by the lobar transplant for more than one hour. These r esults have prompted a bilateral lobar transplant model and current st udies are in progress.