Measuring reduced cytochrome aa(3) in cadaveric lungs using near-infrared spectroscopy

Background: Researchers are investigating the use of cadaveric lungs to mak e up for the shortage of donors. However, no method to enable accurate eval uation of cadaveric lung viability has been established. We designed the pr esent study to evaluate the viability of cadaveric lung tissue using near-i nfrared spectroscopy (NIRS). Methods: Male Lewis rats were anesthetized, mechanically ventilated, and su bjected to a left thoracotomy. After cardiac arrest induced by an injection of sodium pentobarbital, we continued mechanical ventilation using oxygen (Group 1, n = 16) or nitrogen (Group 2, n = 20). Using NIRS, we monitored t he redox state of cytochrome aa, at intervals of 20 minutes for a period of 5 hours. We harvested the lung tissues of each group at 2 and 5 hours post -mortem and performed pathologic examination. Results: The reduced cytochrome aa, in Group 2 increased from 2 hours post- mortem. We observed no significant changes in Group 1. We found and scored the formation of hyaline membranes, intra-alveolar edema, edema around bron chioles and small vessels, and congestion in the cadaveric lungs. In Group 1, histologic findings were mild to moderate. In Group 2, findings were mod erate at 2 hours post-mortem but became much more severe at 5 hours post-mo rtem Conclusions: The measurement of reduced cytochrome aa, using NIRS may refle ct the histologic condition of cadaveric lung tissue. We expect that this e valuation method will be advantageous for lung transplantation in the futur e.