A study of preservation solution for 48- and 96-hour simple hypothermic storage of canine lung transplants

Forty-eight-hr and 96-hr simple hypothermic preservations of the lung were studied on dogs using 4 kinds of solutions resembling extracellular electrolyte compositions (Ep1-Ep4). The pH of each solution was changed from 6.377 to 7.463 by HPO4(2-)/H2PO4- ratio. Twenty dogs were prepared as donors (12 for 48-hr preservation with Ep1, Ep2 and Ep3, and 8 for 96-hr preservation with Ep3 and Ep4, respectively). The heart-lung block was removed from the donor, and flushed with 500 ml of preservation solution via the pulmonary artery, then immersed in the same cold (4 degrees C) solution, after which it was stored in a cold (4 degrees C) room. After preservation, the left lung was separated from the heart-lung block and was transplanted into the recipient orthotopically. The function of the transplanted lung was evaluated with serial x-ray findings, contralateral pulmonary artery ligation test, and histologic findings. In the case of 48-hr preservation, all of the four recipients with Ep3 (pH: 7.225) showed good aeration of the grafted lungs on the chest x-ray in the early postoperative period. As for the 96-hr preservation cases, one with Ep3 and three with Ep4 (pH: 7.463) presented good x-ray findings. Of these successful cases, seven dogs (5 of 48-hr preservation cases, six dogs tolerated this procedure. On histopathological examination of the successful cases, the 48-hr preservation cases showed almost normal pulmonary structure, while the 96-hr preservation cases showed slight degenerative changes in the alveolar walls. From the present study, it becomes apparent that clinical application of 48-hr preservation may be possible by using a phosphate buffered extracellular solution.