Improved lung function by means of retrograde flush in canine lung transplantation with non-heart-beating donors

Objective: Use of lungs from non-heart-beating donors would increase the pulmonary donor pool. The aim of this study was to evaluate the effects of retrograde flush in canine lung transplantation from non-heart-beating donors. Methods: Left lung transplantation was performed in 12 weight-matched pairs of dogs. Donors were killed without heparinization, left at room temperature for 2 hours, and then randomized into 2 groups. In group AF (n = 6) lung retrieval was performed after flushing the lung block with low potassium dextran glucose (50 mL/kg) solution through the pulmonary artery. In group AF+RF (n = 6) additional retrograde flushing (low potassium dextran glucose, 25 mL/kg) was performed through the left atrium before retrieval. Flushed solution was sampled at intervals to measure hemoglobin concentrations. The lungs were preserved at 4°C for 2 hours, and the left lung was implanted to the recipient being subjected to a total ischemic time of 5 hours. After left lung transplantation, the right pulmonary artery and main bronchus were ligated. Lung function, including arterial blood gas and pulmonary hemodynamics, was measured for 3 hours. For lung function study, statistical analyses were performed by using 1-way analysis of variance with repeated measures. Results: Group AF+RF had significantly better gas exchange and lower wet/dry weight ratio of the transplanted lung than group AF. Changes of hemoglobin concentration in the flushed solution indicated that additional retrograde flush could remove residual microthrombi after antegrade flush. Conclusions: This study supports the theory that additional retrograde flush improves lung function after lung transplantation by removing residual pulmonary microthrombi in the lungs of non-heart-beating donors.