Retrograde versus antegrade flush in canine left lung preservation for six hours

Retrograde flush through the left atrium is now used by some investigators in clinical lung preservation. However, to date there are no studies which compare its result with that of routine antegrade flush.

Mongrel dogs were divided into two groups: antegrade group (n = 7) and retrograde group (n = 8). After flush and 6 hours of cold storage in Euro-Collins solution, the left lung was transplanted in weight matched recipients, and their right pulmonary artery was then clamped at 10-, 30-, 60-, and 120-minute intervals for 10 minutes to test the lung function. The ultrastructure of lungs in both groups were also studied.

Results showed the following (antegrade group versus retrograde group): the wet/dry ratio of the transplanted lung was 7.14 +/- 0.15 versus 6.33 +/- 0.20 (p < 0.01); the arterial oxygen tension (mm Hg) was 389 +/- 42 versus 534 +/- 23 (p < 0.05) and 370 +/- 51 versus 580 +/- 37 (p < 0.01) at 60 and 120 minutes, respectively. The peak airway pressure (cm H2O) was 23.4 +/- 0.8 versus 20.6 +/- 0.6 (p < 0.05) and 23.7 +/- 0.6 versus 21.3 +/- 0.8 (p < 0.05) at 10 and 60 minutes, respectively. Electron microscopic studies showed that at the end of preservation, type I and type II pneumocytes and capillaries were normal in both groups. Occluded capillaries with red blood cells were found in the antegrade group. After reperfusion, damaged epithelium and thicker air-blood barrier were found in the antegrade group.

Retrograde flush offers a better lung preservation with less edema, decreased airway resistance, and improved oxygenation as compared with the antegrade group in 6 hours lung preservation.