Effects of inhaled nitric oxide in a canine living-donor lobar lung transplant model

In living-donor lobar lung transplantation, early severe graft dysfunction can occur if the size or amount of transplanted lung tissue is insufficient. The purpose of this study was to evaluate the effects of inhaled nitric oxide on early pulmonary function in a canine bilateral living-donor lobar lung transplant model.

Sixteen pairs of mongrel dogs with a donor/recipient weight ratio less than 1.2 were used. The donor lung bloc was extirpated after heparinization. Right middle, lower and cardiac lobes were implanted as a right lung of the recipient and left lower lobe was implanted as a left lung without cardiopulmonary bypass. In Group 1 (n = 9), nitric oxide gas was administered continuously at a concentration of 40 parts per million prior to reperfusion of the right lung throughout the 6-hour assessment period after transplantation. In Group 2 (n = 7), nitrogen gas was administered in the same manner as nitric oxide, for control.

At the end of assessment, the survival rate was 89% (8/9) in Group 1 and 57% (4/7) in Group 2. The arterial oxygen tension in Group 1 was significantly higher than that in Group 2. The pulmonary arterial pressure and pulmonary vascular resistance index were significantly lower in Group 1 than in Group 2. The aortic pressure and cardiac index did not differ significantly between the two groups. The wet-to-dry weight ratio and myeloperoxidase activity were significantly lower in Group 1 than in Group 2.

These data suggested that inhaled nitric oxide improved early pulmonary function in living-donor lobar lung transplantation by vasodilatating the pulmonary vasculature and inhibiting neutrophil activation.