PREHARVEST NITROPRUSSIDE FLUSH IMPROVES POSTTRANSPLANTATION LUNG-FUNCTION

Background: Morbidity as a result of early allograft dysfunction remai ns a significant problem in clinical lung transplantation We previousl y demonstrated that nitroprusside (NP), a potent nitric oxide donor, a dministered before storage and again during reperfusion, reduced lung reperfusion injury. The purpose of the present study was to determine whether these observations were storage effects, reperfusion effects, or both. Materials and Methods: Fifteen dogs underwent left lung allot ransplant. Donor lungs were flushed with modified Euro-Collins solutio n and stored for 21 hours at 1 degrees C. Immediately after transplant ation, the contralateral right main pulmonary artery and bronchus were ligated to assess isolated allograft function. Hemodynamics and arter ial blood gas analysis (FIO2 1.0) were assessed for 6 hours before sac rifice. Allograft myeloperoxidase (MPO) activity and wet to dry weight (W/D) ratio were assessed. Animals were divided into three groups for timing of NP administration. Group I (n = 5) animals received no NP. In group II (n = 5), donor lungs received NP (10 mg/L) in the flush so lution only. In group III (n = 5), recipient animals received NP (0.2 mg/kg) just before reperfusion, as well as a continuous infusion (0.1 mg/kg/hr) during the assessment period. Results: Significant improveme nt in gas exchange was apparent in groups II and III compared with gro up I, but there was no significant difference between groups II and II I. After 6-hour reperfusion, mean Pao(2) values were 85.46 +/- 13.32 m m Hg in group I; 298.74 +/- 61.25 mm Hg in group II (p < 0.05), and 31 1.12 +/- 43.39 mm Hg in group III (p < 0.05). Systemic vascular resist ance was significantly lower in group III than in group I(p < 0.05). M PO activities decreased in groups II (p < 0.05) and III (p < 0.05), in dicating reduced neutrophil sequestration. W/D ratio was significantly lower in groups II and III. Conclusion: Both methods of NP administra tion are effective, but NP administration in the recipient is accompan ied by a decrease in systemic vascular resistance. From a clinical poi nt of view, NP administration in the flush solution is a sufficiently effective and practical method to reduce lung allograft reperfusion in jury.