Comparative study of solutions for pulmonary preservation using an isolated rabbit lung model

At the University of Minnesota, University of Wisconsin (UW), modified Euro-Collins (MEC), and Marshall (M) solutions were compared as agents for pulmonary preservation in an isolated rabbit lung model. Normal saline (NS) was used as a control. The heart-lung blocks of donor rabbits were flushed with, and then preserved in, one of the solutions at 4°C. Five rabbits were studied in each group. After 8 h of cold ischemia, the left lung was ventilated and reperfused with fresh venous blood from donor rabbits for 30 min. Pulmonary function was assessed by serial measurements of oxygen (O₂) and carbon dioxide (CO₂) tensions in blood obtained from the left atrial appendage. The ratios of wet/dry (W/D) weight of the lungs were calculated to assess the extent of pulmonary edema. After 8 h of preservation followed by 30 min of reperfusion, O₂ tension was significantly higher with UW (178.36 + 1.72 mmHg). The calculated P values were UW vs NS, <0.0001; UW vs MEC, 0.154; and UW vs M, 0.0001. CO₂ tension with UW was also lower than the other solutions: UW, 35.8 ± 0.698 mmHg; NS, 48.5 ± 0.745 mmHg; MEC, 40.69 ± 0.749 mmHg; and M, 44.68 ± 0.697 mmHg. The calculated P value was UW vs NS, 0.0001; UW vs MEC, 0.0003; and UW vs M, 0.0001 using repeated-measures analysis of covariance. The W/D ratio was lower with UW as well: UW, 6.82 ± 0.19; NS, 8.01 ± 0.23; MEC, 7.28 ± 0.10; and M, 7.34 ± 0.17. The P value was <0.001 using post-hoc tests. In this model, UW solution preserved the lungs better than the other three solutions tested and therefore warrants further clinical application.