Comparison of Extracellular-Type-Kyoto Solution and Perfadex as a Preservation Solution in a Pig Ex Vivo Lung Perfusion Model: Impact of Potassium Level

Background. The ex vivo lung perfusion (EVLP) system has been used successfully to assess donor lungs. Perfadex (PX) is usually the flush and preservation solution in EVLP systems. We have used the extracellular-type Kyoto (ET-K) solution containing 44 mEq/L potassium for clinical lung transplantation, investigating whether it rather than PX affects the EVLP system. Methods. We used domestic slaughterhouse pigs to analyze the EVLP system. After 20-minute warm ischemia and 6-hour cold ischemia, EVLP was performed for 2 hours. Pig heart-lung blocks were divided into the PX (n = 5) and ET-K (n = 5) groups depending on the flush/cold preservation solution. At the beginning, we discarded the first 100 mL of effluent in the PX group and the first 200 mL in the ET-K group. We measured pulmonary physiological data and potassium levels. Results. In both groups, perfusion for 2 hours showed no differences between the 2 groups with respect to the final flow, pulmonary arterial pressure, pulmonary vascular resistance, PaO(2)/FiO(2), and shunt fraction. The potassium level in the perfusate was 4.4 mEq/L for the PX and 5.4 mEq/L for the ET-K group. Conclusion. The pig EVLP system was not affected when ET-K was used instead of PX as the flush/preservation solution. The initial 200 mL of effluent should be discarded when using the ET-K to ensure that the potassium level does not increase.