Ex vivo lung perfusion in Brazil / A experiência brasileira na perfusão pulmonar ex vivo

Objective: To evaluate the use of ex vivo lung perfusion (EVLP) clinically to prepare donor lungs for transplantation. Methods: A prospective study involving EVLP for the reconditioning of extended-criteria donor lungs, the criteria for which include aspects such as a PaO2/FiO2 ratio < 300 mmHg. Between February of 2013 and February of 2014, the lungs of five donors were submitted to EVLP for up to 4 h each. During EVLP, respiratory mechanics were continuously evaluated. Once every hour during the procedure, samples of the perfusate were collected and the function of the lungs was evaluated. Results: The mean PaO2 of the recovered lungs was 262.9 ± 119.7 mmHg at baseline, compared with 357.0 ± 108.5 mmHg after 3 h of EVLP. The mean oxygenation capacity of the lungs improved slightly over the first 3 h of EVLP-246.1 ± 35.1, 257.9 ± 48.9, and 288.8 ± 120.5 mmHg after 1, 2, and 3 h, respectively-without significant differences among the time points (p = 0.508). The mean static compliance was 63.0 ± 18.7 mmHg, 75.6 ± 25.4 mmHg, and 70.4 ± 28.0 mmHg after 1, 2, and 3 h, respectively, with a significant improvement from hour 1 to hour 2 (p = 0.029) but not from hour 2 to hour 3 (p = 0.059). Pulmonary vascular resistance remained stable during EVLP, with no differences among time points (p = 0.284). Conclusions: Although the lungs evaluated remained under physiological conditions, the EVLP protocol did not effectively improve lung function, thus precluding transplantation.

Objetivo: Avaliar o emprego da técnica de perfusão pulmonar ex vivo (PPEV) clinicamente com a finalidade de transplante. Métodos: Estudo prospectivo envolvendo o recondicionamento de pulmões limítrofes, definidos por critérios específicos, tais como relação PaO2/FiO2 < 300 mmHg, com um sistema de PPEV. Entre fevereiro de 2013 e fevereiro de 2014, os pulmões de cinco doadores foram submetidos à PPEV por até 4 h. Durante a PPEV, a mecânica pulmonar foi avaliada continuamente. Amostras do perfusato foram colhidas a cada hora, assim como foi realizada a avaliação funcional dos órgãos. Resultados: A média de PaO2 dos pulmões captados foi de 262,9 ± 119,7 mmHg, sendo que, ao final da terceira hora de perfusão, essa foi de 357,0 ±108,5 mmHg. A capacidade de oxigenação dos pulmões apresentou discreta melhora durante a PPEV nas primeiras 3 h (246,1 ± 35,1; 257,9 ± 48,9; e 288,8 ± 120,5 mmHg, respectivamente), sem diferenças significativas entre os momentos (p = 0,508). As médias de complacência estática foram de, respectivamente, 63.0 ± 18,7; 75,6 ± 25,4; e 70,4 ± 28,0 mmHg após 1, 2 e 3 h, com melhora significativa entre a hora 1 e 2 (p = 0,029), mas não entre a hora 2 e 3 (p = 0,059). A resistência vascular pulmonar permaneceu estável durante a PPEV, sem diferenças entre os momentos (p = 0,284). Conclusões: Os pulmões avaliados permaneceram em condições fisiológicas de preservação; no entanto, o protocolo não foi efetivo para promover a melhora na função pulmonar, inviabilizando o transplante.

Alternative solution for ex vivo lung perfusion, experimental study on donated human lungs non-accepted for transplantation

PURPOSE: To evaluate a new perfusate solution to be used for ex vivo lung perfusion. METHODS: Randomized experimental study using lungs from rejected brain-dead donors harvested and submitted to 1 hour of ex vivo lung perfusion (EVLP) using mainstream solution or the alternative. RESULTS: From 16 lungs blocs tested, we found no difference on weight after EVLP: Steen group (SG) = 1,097±526g; Alternative Perfusion Solution (APS) = 743±248g, p=0.163. Edema formation, assessed by Wet/dry weigh ratio, was statistically higher on the Alternative Perfusion Solution group (APS = 3.63 ± 1.26; SG = 2.06 ± 0.28; p = 0.009). No difference on PaO2 after EVLP (SG = 498±37.53mmHg; APS = 521±55.43mmHg, p=0.348, nor on histological analyses: pulmonary injury score: SG = 4.38±1.51; APS = 4.50±1.77, p=0.881; apoptotic cells count after perfusion: SG = 2.4 ± 2.0 cells/mm2; APS = 4.8 ± 6.9 cells/mm2; p = 0.361). CONCLUSION: The ex vivo lung perfusion using the alternative perfusion solution showed no functional or histological differences, except for a higher edema formation, from the EVLP using Steen Solution(r) on lungs from rejected brain-dead donors. .

Comparison of Celsior and Perfadex lung preservation solutions in rat lungs subjected to 6 and 12 hours of ischemia using an ex-vivo lung perfusion system

OBJECTIVE: This study evaluated the performance of lungs that were preserved with different solutions (Celsior, Perfadex or saline) in an ex vivo rat lung perfusion system. METHODS: Sixty Wistar rats were anesthetized, anticoagulated and randomized into three groups (n = 20). The rats were subjected to antegrade perfusion via the pulmonary artery with Perfadex, Celsior, or saline, followed by 6 or 12 hours of ischemia (4ºC, n = 10 in each group). Respiratory mechanics, gas exchange and hemodynamics were measured at 10-minute intervals during the reperfusion of heart-lung blocks in an ex vivo system (IL2-Isolated Perfused Rat or Guinea Pig Lung System, Harvard Apparatus, Holliston, Massachusetts, USA; Hugo Sachs Elektronik, Germany) for 60 minutes. The lungs were prepared for histopathology and evaluated for edema following reperfusion. Group comparisons were performed using ANOVA and the Kruskal-Wallis test with a 5% level of significance. RESULTS: Gas exchange was not significantly different between lungs perfused with either Perfadex or Celsior at the same ischemic times, but it was very low in lungs that were preserved with saline. Airway resistance was greater in the lungs that were preserved for 12 hours. Celsior lungs that were preserved for 6 and 12 hours exhibited lower airway resistance (p = 0.01) compared to Perfadex lungs. Pulmonary artery pressure was not different between the groups, and no significant differences in histopathology and apoptosis were observed between the groups. CONCLUSIONS: Lungs that were preserved with Celsior or Perfadex exhibited similar gas exchange and histopathological findings. Airway resistance was slightly lower in the Celsior-preserved lungs compared with the Perfadex-preserved lungs.

Modelo experimental de perfusão pulmonar ex vivo em ratos: avaliação histopatológica e de apoptose celular em pulmões preservados com solução de baixo potássio dextrana vs. solução histidina-triptofano-cetoglutarato / An experimental rat model of ex vivo lung perfusion for the assessment of lungs regarding histopathological findings and apoptosis: low-potassium dextran vs. histidine-tryptophan-ketoglutarate

OBJETIVO: Comparar os achados histopatológicos e de apoptose em pulmões de ratos preservados em soluções low-potassium dextran (LPD, baixo potássio dextrana), histidine-tryptophan-ketoglutarate (HTK, histidina-triptofano-cetoglutarato) ou salina normal (SN) em 6 h e 12 h de isquemia pela utilização de um modelo experimental de perfusão pulmonar ex vivo. MÉTODOS: Sessenta ratos Wistar foram anestesiados, randomizados e submetidos à perfusão anterógrada pela artéria pulmonar com uma das soluções preservadoras. Após a extração, os blocos cardiopulmonares foram preservados por 6 ou 12 h a 4ºC, sendo então reperfundidos com sangue homólogo em um sistema de perfusão ex vivo durante 60 min. Ao final da reperfusão, fragmentos do lobo médio foram extraídos e processados para histopatologia, sendo avaliados os seguintes parâmetros: congestão, edema alveolar, hemorragia alveolar, hemorragia, infiltrado inflamatório e infiltrado intersticial. O grau de apoptose foi avaliado pelo método TdT-mediated dUTP nick end labeling. RESULTADOS: A histopatologia demonstrou que todos os pulmões preservados com SN apresentaram edema alveolar após 12 h de isquemia. Não houve diferenças em relação ao grau de apoptose nos grupos estudados. CONCLUSÕES: No presente estudo, os achados histopatológicos e de apoptose foram semelhantes com o uso das soluções LPD e HTK, enquanto a presença de edema foi significativamente maior com o uso de SN.

OBJECTIVE: To compare histopathological findings and the degree of apoptosis among rat lungs preserved with low-potassium dextran (LPD) solution, histidine-tryptophan-ketoglutarate (HTK) solution, or normal saline (NS) at two ischemia periods (6 h and 12 h) using an experimental rat model of ex vivo lung perfusion. METHODS: Sixty Wistar rats were anesthetized, randomized, and submitted to antegrade perfusion via pulmonary artery with one of the preservation solutions. Following en bloc extraction, the heart-lung blocks were preserved for 6 h or 12 h at 4ºC and then reperfused with homologous blood for 60 min in an ex vivo lung perfusion system. At the end of the reperfusion, fragments of the middle lobe were extracted and processed for histopathological examination. The parameters evaluated were congestion, alveolar edema, alveolar hemorrhage, inflammatory infiltrate, and interstitial infiltrate. The degree of apoptosis was assessed using the TdT-mediated dUTP nick end labeling method. RESULTS: The histopathological examination showed that all of the lungs preserved with NS presented alveolar edema after 12 h of ischemia. There were no statistically significant differences among the groups in terms of the degree of apoptosis. CONCLUSIONS: In this study, the histopathological and apoptosis findings were similar with the use of either LPD or HTK solutions, whereas the occurrence of edema was significantly more common with the use of NS.

The effects on mucociliary clearance of prednisone associated with bronchial section

OBJECTIVE: Infections have been and remain the major cause of morbidity and mortality after lung transplantation. Because mucociliary clearance plays an important role in human defense mechanisms, the influence of drugs on the mucociliary epithelium of patients undergoing lung transplantation must be examined. Prednisone is the most important corticosteroid used after lung transplantation. The aim of this study was to evaluate the effects of bronchial transection and prednisone therapy on mucociliary clearance. METHODS: A total of 120 rats were assigned to 4 groups according to surgical procedure or drug therapy: prednisone therapy (1.25 mg/kg/day); bronchial section and anastomosis + prednisone therapy (1.25 mg/kg/day); bronchial section + saline solution (2 ml/day); and saline solution (2 ml/day). After 7, 15, or 30 days, the animals were sacrificed, and the lungs were removed from the thoracic cavity. The in situ mucociliary transport velocity, ciliary beat frequency and in vitro mucus transportability were evaluated. RESULTS: Animals undergoing bronchial section surgery and anastomosis had a significant decrease in the ciliary beat frequency and mucociliary transport velocity 7 and 15 days after surgery (p<0.001). These parameters were normalized 30 days after the surgical procedure. Prednisone improved mucous transportability in the animals undergoing bronchial section and anastomosis at 15 and 30 days (p<0.05). CONCLUSION: Bronchial section and anastomosis decrease mucociliary clearance in the early postoperative period. Prednisone therapy improves mucus transportability in animals undergoing bronchial section and anastomosis.