[Experimental studies on reimplantation response after lung transplantation]

The reimplantation response after lung transplantation may critically impair the function of transplanted lungs in the early postoperative period. The purpose of this study is to evaluate the factors which cause this reimplantation response. Using canine left lungs, four groups were studied. Group I underwent complete hilar stripping (n = 6). Group II underwent complete hilar stripping and kept in warm ischemia for 60 min. by clamping left pulmonary artery and veins (n = 6). Group III underwent the same surgery as Group II and administered superoxide dismutase (SOD) (12000 U/kg/h) during reperfusion (n = 7). Group IV underwent autotransplantation of left lung (n = 6). To evaluate the function of left lung, arterial blood gas, pulmonary arterial pressure, aortic pressure, cardiac output and left extravascular lung water (liter EVLW) were measured in a transient contralateral pulmonary arterial occlusion before operation and 60 min. after reventilation and reperfusion. The measurement of EVLW was performed by thermal-green dye double indicator dilution method. The results obtained were as follows. 1) The values of liter EVLW measured in rt. pulmonary arterial occlusion were extremely well correlated with those of both lung EVLW. (r = 0.943 p less than 0.001). 2) The ratios of postoperative-liter EVLW: preoperative-liter EVLW and postoperative-total pulmonary resistance (TPR): preoperative-TPR were as follows: Group I; 1.29 +/- 0.19 and 1.23 +/- 0.36, Group II; 1.85 +/- 0.49 and 1.69 +/- 0.36, Group III; 1.28 +/- 0.17 and 1.50 +/- 0.36 Group IV; 2.28 +/- 0.40 and 1.70 +/- 0.34. These data indicate that the most important factor of reimplantation response at the time of this acute phase is the oxygen free radical-induced reperfusion injury. Hilar stripping, ischemic injury and surgical trauma are also important factors of reimplantation response. Vascular anastomosis is not so important when it is done well technically. 3) Administration of SOD provides protection against lung edema after lung transplantation.