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The overproduction of reactive oxygen species plays an important role in the cascade of events during lung ischemia-reperfusion leading to graft failure. An evaluation of the peripheral markers of oxidative stress and antioxidant enzyme activities was carried out after reperfusion in a rat lung transplant model. The decrease in lipid peroxidation immediately after transplantation ( P < 0.05) may suggest an adaptative response and/or a protective effect of low potassium dextran against lipid peroxidation through natural scavenging mechanisms.

The increasing demand in transplantation research requires efficient and less expensive animal models in order to obtain reliable results that are reproducible in larger animal models and, ultimately, applied clinically. The model of unilateral left lung transplantation in rats has proven to be a useful alternative for those purposes. We demonstrate a technical modification of this model, which consists of the isolation and ligation of the contralateral (right) pulmonary artery, allowing blood circulation exclusively in the transplanted lung. This model is feasible and reproducible. However, the short survival time restricts the assessment of the transplanted lung to a maximum period of three hours.

Objective: To compare the influence of two different ventilation strategies-volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV)-on the functional performance of lung grafts in a canine model of unilateral left lung transplantation using donor lungs harvested after three hours of normothermic cardiocirculatory arrest under mechanical ventilation. Methods: The study comprised 40 mongrel dogs, randomized into two groups: VCV and PCV. Of the 20 recipients, 5 did not survive the transplant, and 5 died before the end of the post-transplant assessment period. The remaining 10 survivors (5 in each group) were evaluated for 360 min after lung transplantation. The functional performance of the grafts was evaluated regarding respiratory mechanics, gas exchange, and lung graft histology. Results: There were no significant differences between the groups regarding respiratory mechanics (peak inspiratory pressure, plateau pressure, mean airway pressure, dynamic compliance, and static compliance) or gas exchange variables (PaO 2 , venous oxygen tension, PaCO 2 , venous carbon dioxide tension, and the arterial-venous oxygen content difference). The histopathological findings were consistent with nonspecific acute lung injury and did not differ between the groups. Conclusions: This model of lung transplantation showed that the functional performance of lung grafts was not influenced by the ventilation strategy employed during the first six hours after reperfusion.Keywords: Pulmonary ventilation; Respiration, artificial; Lung transplantation; Dogs; Organ preservation. ResumoObjetivo: Comparar a influência de duas estratégias ventilatórias -ventilação controlada a volume (VCV) e ventilação controlada a pressão (VCP) -no desempenho funcional de enxertos pulmonares em um modelo canino de transplante pulmonar unilateral esquerdo, utilizando-se doadores cujos pulmões foram captados após três horas de parada cardiocirculatória em temperatura ambiente e sob ventilação mecânica. Métodos: O estudo incluiu 40 cães mestiços randomizados nos grupos VCV e VCP. Dos 20 receptores, 5 não sobreviveram ao transplante, e 5 não sobreviveram ao período de avaliação pós-transplante. Os 10 receptores sobreviventes (5 em cada grupo) foram avaliados durante 360 min após o término do transplante pulmonar. O desempenho funcional dos enxertos foi estudado através da avaliação da mecânica respiratória, trocas gasosas e histologia do enxerto. Resultados: Não houve diferenças significativas entre os grupos quanto às variáveis de mecânica respiratória (pressão de pico inspiratória, pressão de platô, pressão média de vias aéreas, complacência dinâmica e complacência estática) e de trocas gasosas (PaO 2 , pressão venosa mista de oxigênio, PaCO 2 , pressão venosa mista de CO 2 e diferença arteriovenosa de oxigênio). As alterações histopatológicas foram compatíveis com o padrão de lesão pulmonar aguda não específica e não diferiram entre os grupos. Conclusões: Este modelo de transplante pulmonar mostrou que o desempenho funcional do...