RETROGRADE VERSUS ANTEGRADE FLUSH IN CANINE LEFT LUNG PRESERVATION FOR 6 HOURS

Background: Retrograde flush through the left atrium is now used by so me investigators in clinical lung preservation. However, to date there are no studies which compare its result with that of routine antegrad e flush. Methods: Mongrel dogs were divided into two groups: antegrade group (n = 7) and retrograde group (n = 8). After flush and 6 hours o f cold storage in Euro-Collins solution, the left lung was transplante d in weight matched recipients, and their right pulmonary artery was t hen 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: Results showed the following (antegrade gr oup versus retrograde group): the wet/dry ratio of the transplanted lu ng was 7.14 +/- 0.15 versus 6.33 +/- 0.20 (p < 0.01); the arterial oxy gen tension (mm Hg) was 389 +/- 42 versus 534 +/- 23 (p < 0.05) and 37 0 +/- 51 versus 580 +/- 37 (p < 0.01) at 60 and 120 minutes, respectiv ely. 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 tha t at the end of preservation, type I and type II pneumocytes and capil laries were normal in both groups. Occluded capillaries with red blood cells were found in the antegrade group. After reperfusion, damaged e pithelium and thicker air-blood barrier were found in the antegrade gr oup. Conclusions: Retrograde flush offers a better lung preservation w ith less edema, decreased airway resistance, and improved oxygenation as compared with the antegrade group in 6 hours lung preservation.