ET-Kyoto solution for 48-hour canine lung preservation

Background. ET-Kyoto (ET-K) solution, proven safe for 20-hour lung preservation, was modified to achieve longer preservation: ET-K2 solution with more buffer capacity and ET-K3 solution with less potassium. Methods. Lungs were preserved with one of the three solutions (with prostaglandin E1) at 4°C for 48 hours (n = 5 for each). Left lung transplantation was performed and evaluated for 6 hours. Results. Each solution became acidic after preservation (p < 0.01), though the change was lowest in the ET-K2 solution. All animals in the ET-K and ET-K3 groups survived for 6 hours after reperfusion, but only 1 survived in the ET-K2 group (p < 0.05). In all groups, partial pressure of oxygen in arterial blood decreased gradually after reperfusion. Pulmonary vascular resistance after reperfusion was significantly lower in the ET-K group than in the ET-K3 group (p < 0.01). Scanning electron microscopic examination showed that endothelial cell swelling and disruption were milder in the ET-K group (with solution containing potassium of 44 mEq/L) than in the ET-K3 group. Conclusion. Lung preservation can be achieved for 48 hours in ET-K and ET-K3 solutions. Enhancement of buffer capacity provides no advantage. Potassium at 44 mEq/L does not cause deterioration of endothelial cells.