Reduced lipid peroxidation and ischemia-reperfusion injury after lung transplantation using low-potassium dextran solution for lung preservation

Extracorporeal Perfusion in Vascularized Composite Allotransplantation: Current Concepts and Future Prospects

Severe injuries of the face and limbs remain a major challenge in today's reconstructive surgery. Vascularized composite allotransplantation (VCA) has emerged as a promising approach to restore these defects. Yet, there are major obstacles preventing VCA from broad clinical application. Two key restrictions are (1) the graft's limited possible ischemia time, keeping the potential donor radius extremely small, and (2) the graft's immunogenicity, making extensive lifelong monitoring and immunosuppressive treatment mandatory. Machine perfusion systems have demonstrated clinical success addressing these issues in solid organ transplantation by extending possible ischemia times and decreasing immunogenicity. Despite many recent promising preclinical trials, machine perfusion has not yet been utilized in clinical VCA. This review presents latest perfusion strategies in clinical solid organ transplantation and experimental VCA in light of the specific requirements by the vascularized composite allograft's unique tissue composition. It discusses optimal settings for temperature, oxygenation, and flow types, as well as perfusion solutions and the most promising additives. Moreover, it highlights the implications for the utility of VCA as therapeutic measure in plastic surgery, if machine perfusion can be successfully introduced in a clinical setting.

Quantification of propionaldehyde in breath of patients after lung transplantation

Oxygen-derived free radicals (ROS) have been identified to contribute significantly to ischemia-reperfusion (I/R) injury by initiating chain reactions with polyunsaturated membrane lipids (lipid peroxidation, LPO) resulting in the generation of several aldehydes and ketones. Due to their volatile nature these LPO products can be measured noninvasively in breath. We hypothesized that one of these markers, namely propionaldehyde, will be increased in lung and heart-lung transplant patients where severe oxidative stress due to I/R injury with early graft dysfunction represents one of the major postoperative complications resulting in prolonged ventilation and increased in-hospital morbidity and mortality. Expiratory air measurements for acetone, isoprene, and propionaldehyde were performed in seven patients after lung (n = 5) or heart-lung (n = 2) transplantation, ventilated patients (n = 12), and healthy volunteers (n = 17) using online ion-molecule reaction mass spectrometry. Increased concentrations of acetone (transplanted: 3812 [2347-12498]; ventilated: 1255 [276-1959]; healthy: 631 [520-784] ppbv; P < .001) and propionaldehyde (transplanted: 270 [70-424]; ventilated: 82 [41.8-142]; healthy: 1.7 [0.1-11.8] ppbv; P < .001) were found in expiratory air of transplanted and ventilated patients. Propionaldehyde resulting from spontaneous fragmentation of peroxides due to free radical-induced LPO after I/R injury in patients after lung or heart-lung transplantation can be quantified in expired breath.

Engineering dextran-based scaffolds for drug delivery and tissue repair

Owing to its chemically reactive hydroxyl groups, dextran can be modified with different functional groups to form spherical, tubular and 3D network structures. The development of novel functional scaffolds for efficient controlled release and tissue regeneration has been a major research interest, and offers promising therapeutics for many diseases. Dextran-based scaffolds are naturally biodegradable and can serve as bioactive carriers for many protein biomolecules. The reconstruction of the in vitro microenvironment with proper signaling cues for large-scale tissue regenerative scaffolds has yet to be fully developed, and remains a significant challenge in regenerative medicine. This paper will describe recent advances in dextran-based polymers and scaffolds for controlled release and tissue engineering. Special attention is given to the development of dextran-based hydrogels that are precisely manipulated with desired structural properties and encapsulated with defined angiogenic growth factors for therapeutic neovascularization, as well as their potential for wound repair.

A new preservation solution for lung transplantation: evaluation in a porcine transplantation model

BACKGROUND

Lung preservation injury is still a major problem in lung transplantation. The aim of the current study was to evaluate the effects of a new preservation solution (Custodiol-N) for lung preservation.

METHODS

Using an in vivo pig model, 7 lungs each were preserved for 24 hours after perfusion with: low-potassium dextran (LPD) solution as control (Group I); base solution of Custodiol-N without iron chelators (Group II); Custodiol-N (Group III); or Custodiol-N supplemented with dextran 40 (Group IV). Four animals received a sham operation. After left lung transplantation and contralateral lung exclusion, hemodynamics and blood gases were monitored for 6 hours; tissue samples were taken at the end of the experiments.

RESULTS

All animals survived the transplantation procedure. Base solution- and Custodiol-N-preserved lungs (Groups II and III) showed graft function similar to that of LPD-preserved lungs (Group I), showing a trend toward improved values. Custodiol-N with dextran (Group IV) led to a significant reduction of mean pulmonary arterial pressure (20 ± 2 vs 28 ± 3 mm Hg, p < 0.01) and pulmonary vascular resistance (410 ± 51 vs 588 ± 83 dyne/s/cm(5), p < 0.01), and oxygenation ratio was significantly higher (536 ± 52 vs 313 ± 107 mm Hg at 6 hours, p < 0.01) and PCO(2) values were significantly lower (51 ± 9 vs 77 ± 5 mm Hg at 6 hours, p < 0.01) at 6 hours compared with LPD (Group I). Custodiol-N (Groups II to IV) showed a trend toward a lower wet/dry ratio and reduced oxidative stress; in the presence of dextran (Group IV), the difference was again statistically significant, when compared with LPD (Group I).

CONCLUSIONS

Custodiol-N solution is a new alternative preservation solution for lung transplantation that offers significantly superior protection compared with LPD when dextran 40 is added.

Dynamic instability of central airways and peripheral airspace in rat lungs perfused with cold preservation solutions

BACKGROUND/AIMS

For lung preservation, one of two types of solutions is commonly employed: Euro-Collins (EC) or low potassium dextran glucose (LPDG). These two solutions have been compared regarding biological, morphometrical and physiological outcomes in many experiments. However, the dynamic mechanics of perfused lung are not well understood because the dynamic characteristics cannot be assessed under static conditions; hence, the primary goal of the present study was to assess this in perfused rat lungs during the preservation period, comparing EC with LPDG at 0 or 9 h at 4°C.

METHODS

Lung impedance was measured using a forced oscillation technique. Lung resistance and elastance values were obtained by the fast Fourier transform algorithm. The instability of central airways and heterogeneity of ventilation were estimated.

RESULTS

In the EC group, airway resistance and instability were high after perfusion, and the lung elastance was high and more heterogeneous after cold storage. In contrast, those parameters were stable in the LPDG group during cold storage.

CONCLUSION

Such dynamic stability might facilitate the handling of lung grafts and eliminate injurious cyclic ventilation stress after reperfusion. Thus, we conclude that the impedance frequency characteristic represents a novel informative parameter for investigating lung preservation techniques.

Risk factors for early primary graft dysfunction after lung transplantation: a registry study

BACKGROUND

Primary graft dysfunction (PGD) is a leading cause of early morbidity and mortality in lung transplantation. We sought to identify risk factors for PGD using the United Network for Organ Sharing/International Society for Heart and Lung Transplant (UNOS/ISHLT) Registry.

METHODS

A total of 6984 lung transplants between 1994 and 2002 were available for analysis. Potential risk factors were tested for association with PGD and multivariable logistic regression was applied to adjust for confounding.

RESULTS

The overall incidence of PGD was 10.7% (95% CI 9.9-11.4). In multivariable analyses, factors independently associated with PGD were donor age >45 yr (p < 0.001); donor head trauma (p = 0.03); recipient body mass index >25 kg/m(2) (p = 0.005); recipient female gender (p = 0.001); use of Eurocollins preservation solution (p = 0.001); single lung transplant (p = 0.005); increased ischemic time (p < 0.001); and elevated recipient pulmonary artery systolic pressure at transplant (p < 0.001). Recipient transplant diagnosis was strongly associated with PGD, with primary or secondary pulmonary hypertension (p < 0.001 for both), and idiopathic (p < 0.001) or secondary pulmonary fibrosis (p = 0.011) as significant and independent risk factors for PGD.

CONCLUSIONS

Risk factors for PGD in the UNOS/ISHLT registry are consistent with prior smaller studies. Recipient, donor, and therapy variables are independently associated with PGD, as defined in a large registry.

Does the method of lung preservation influence outcome after transplantation? An analysis of 681 consecutive procedures

OBJECTIVE

Despite 50 years of lung preservation research, the optimal preservation technique is undefined. Using data from a national cohort, we investigated outcomes with different preservation methods after adult lung transplantation.

METHODS

Early (30-day), late (30-day to 3-year), and overall (3-year) mortalities, adjusted for differences in donor and recipient characteristics, were compared by using Cox regression. Intensive care unit length of stay and the number of rejection episodes were secondary outcomes.

RESULTS

Six hundred eighty-one eligible lung transplantations between July 1995 and June 2003 were preserved with Euro-Collins solution (n = 284), blood albumin (n = 139), core cooling (n = 107), or low potassium dextran solution (n = 151). There was significantly increased use of low potassium dextran solution over time (P < .001). Unadjusted 3-year survival was similar across the groups (P = .72), with the highest 3-year survival in the low potassium dextran group (62%; 95% confidence interval, 51%-72%) and the lowest in the blood albumin group (49%; 95% confidence interval, 39%-58%). Risk-adjusted early (P = .70), late (P = .27), and overall (P = .72) survival was similar across the groups and was not affected by ischemic time. Freedom from death caused by primary graft dysfunction was again highest in the low potassium dextran group (95%; 95% confidence interval, 90%-98%) and lowest in the blood albumin group (91%; 95% confidence interval, 85%-95%). There was no difference in intensive care unit length of stay. An increased incidence of rejection was apparent with increasing ischemic time (P = .067).

CONCLUSION

The methods of lung preservation in current use do not seem to affect early or midterm survival after transplantation, but increasing ischemic time might predispose to increased rejection.

Preischemic iloprost application for improvement of graft preservation: which route is superior in experimental pig lung transplantation: inhaled or intravenous?

BACKGROUND

Optimal allograft protection is essential in lung transplantation to reduce postoperative organ dysfunction. Although intravenous prostanoids are routinely used to ameliorate reperfusion injury, the latest evidence suggests a similar efficacy of inhaled prostacyclin. Therefore, we compared donor lung-pretreatment using inhaled lioprost (Ventavis) with the commonly used intravenous technique.

METHODS

Five pig lungs were each preserved with Perfadex and stored for 27 hours without (group 1) or with (group-2, 100 prior aerosolized of iloprost were (group 3) or iloprost (IV). Following left lung transplantation, hemodynamics, Po(2)/F(i)o(2), compliance, and wet-to-dry ratio were monitored for 6 hours and compared to sham controls using ANOVA analysis with repeated measures.

RESULTS

The mortality was 100% in group 3. All other animals survived (P < .001). Dynamic compliance and PVR were superior in the endobronchially pretreated iloprost group as compared with untreated organs (P < .05), whereas oxygenation was comparable overall W/D-ratio revealed significantly lower lung water in group 2 (P = .027) compared with group 3.

CONCLUSION

Preischemic alveolar deposition of iloprost is superior to IV pretreatment as reflected by significantly improved allograft function. This strategy offers technique to optimize pulmonary preservation.

Impact of preservation solution on the extent of blood-air barrier damage and edema formation in experimental lung transplantation

A major aim in lung transplantation is to prevent the loss of structural integrity due to ischemia and reperfusion (I/R) injury. Preservation solutions protect the lung against I/R injury to a variable extent. We compared the influence of two extracellular-type preservation solutions (Perfadex, or PX, and Celsior, or CE) on the morphological alterations induced by I/R. Pigs were randomly assigned to sham (n = 4), PX (n = 5), or CE (n = 2) group. After flush perfusion with PX or CE, donor lungs were excised and stored for 27 hr at 4 degrees C. The left donor lung was implanted into the recipient, reperfused for 6 hr, and, afterward, prepared for light and electron microscopy. Intra-alveolar, septal, and peribronchovascular edema as well as the integrity of the blood-air barrier were determined stereologically. Intra-alveolar edema was more pronounced in CE (219.80 +/- 207.55 ml) than in PX (31.46 +/- 15.75 ml). Peribronchovascular (sham: 13.20 +/- 4.99 ml; PX: 15.57 +/- 5.53 ml; CE: 31.56 +/- 5.78 ml) and septal edema (thickness of alveolar septal interstitium, sham: 98 +/- 33 nm; PX: 84 +/- 8 nm; CE: 249 +/- 85 nm) were only found in CE. The blood-air barrier was similarly well preserved in sham and PX but showed larger areas of swollen and fragmented epithelium or endothelium in CE. The present study shows that Perfadex effectively prevents intra-alveolar, septal, and peribronchovascular edema formation as well as injury of the blood-air barrier during I/R. Celsior was not effective in preserving the lung from morphological I/R injury.

Early outcomes comparing Perfadex, Euro-Collins, and Papworth solutions in lung transplantation

BACKGROUND

Despite improved surgical techniques and medical management, primary graft dysfunction (PGD) remains a major cause of early morbidity and mortality after lung transplantation. Different types of lung preservation solutions have been developed and applied to clinical use; however, the relative clinical efficacy of these solutions to prevent PGD remains controversial. This study aimed to investigate the effect of the three solutions most commonly used (Perfadex [Vitrolife, Göteborg, Sweden], Papworth, and Euro-Collins [Baxter Healthcare, Old Toongabbie NSW, Australia]) on posttransplant outcomes.

METHODS

Early outcomes from 157 consecutive lung transplants (113 bilateral and 44 single) performed at The Alfred Hospital were compared across three preservation solutions.

RESULTS

Posttransplant oxygenation (p = 0.57), pulmonary vascular resistance (p = 0.34), intubation hours (p = 0.66), intensive care unit days (p = 0.34), severe PGD (grade 3) (p = 0.70), 30-day mortality (p = 0.87), and 3-month % predicted forced expiratory volume in 1 second (p = 0.58) were not statistically different; however, Perfadex trended toward superiority among the three solutions. After adjustment of donor, recipient, and operative factors in multivariate analysis, Perfadex was significantly associated with the prevention of moderate to severe PGD (grade 2 to 3) at 48 hours posttransplant (odds ratio = 0.26 [0.10 to 0.72], p < 0.01) compared with Papworth (odds ratio = 0.75 [0.32 to 1.75], p = 0.51) and Euro-Collins (reference) solutions.

CONCLUSIONS

Although any advantageous effects of Perfadex on early posttransplant outcomes were generally subtle and statistically nonsignificant, Perfadex prevented moderate to severe PGD. Switching preservation solution from Euro-Collins (or Papworth) to Perfadex would appear to usefully contribute to a strategy to reduce PGD in lung transplantation.

Experimental Lung Transplantation: Impact of Preservation Solution and Route of Delivery

BACKGROUND

Optimal preservation of allograft integrity is essential to reduce post-ischemic organ dysfunction after lung transplantation. Retrograde organ preservation leads to homogeneous intrapulmonary distribution and eliminates intravascular thrombi. So far, no comparative studies exist with regard to preservation quality following retrograde preservation with Perfadex and Celsior after extended cold-ischemia intervals.

METHODS

In an in vivo pig model, 5 lungs each were preserved for 27 hours using antegrade or retrograde perfusion techniques with Celsior (Ce(ant)/CE(ret)) and Perfadex (PER(ant)/PER(ret)). After left lung transplantation and contralateral lung exclusion, hemodynamics, oxygenation and dynamic compliance were monitored for 6 hours and compared with sham-operated controls. Pulmonary edema was determined stereologically. Statistics consisted of analysis of variance (ANOVA) with repeated measures.

RESULTS

Mortality of all Celsior-protected lungs was 100% due to severe reperfusion injury with profound lung edema. In contrast, organ preservation with PER(ant) led to sufficient graft function without mortality. Preservation quality after retrograde administration of Perfadex resulted in optimized oxygenation capacity compared with PER(ant) (p = 0.046). Furthermore, intra-alveolar edema was reduced and generally comparable with sham controls. In general, retrograde preservation led to continuous washout of small blood and fibrin clots from the pulmonary capillary system.

CONCLUSIONS

Perfadex solution provided sufficient lung preservation for 27 hours of cold ischemia, and its retrograde application led to significant functional and histologic improvement compared with antegrade perfusion. In contrast, preservation with Celsior solution resulted in lethal post-ischemic outcome, regardless of the route of administration, and therefore must be considered unsuitable for extended lung procurement.

Effects of Short-Term Inhaled Nitric Oxide on Interleukin-8 Release After Single-Lung Transplantation in Pigs

BACKGROUND

Lung transplantation has evolved to become an effective treatment for a variety of end-stage lung diseases. However, severe reperfusion injury is still a major cause for postoperative morbidity and mortality. Although lung reperfusion injury is complex and has not been fully comprehended yet, neutrophil infiltration and cytokine activation have been postulated to play a main role. Recent studies showed that nitric oxide (NO) therapy has salutary effects on lung chronic and acute pathologies because it inhibits interleukin-8 (IL-8) release, but no data have been found on its effects during organ harvest. The aim of this study was to assess whether low doses of inhaled NO pre-treatment at the time of harvesting improves allograft function during early reperfusion in a porcine model.

METHODS

Twenty-two Landrace pigs were randomly assigned to NO-treated and control groups. In NO-treated pigs, NO at 20 ppm was administered 30 min before harvest. During the early allograft reperfusion period IL-8 content, dynamic and static compliance and gas exchange (Pa/FiO2 and PaO2) were measured in both control and NO-treated lungs.

RESULTS

Pre-treatment with NO at the time of harvesting showed improvement of allograft function in terms of dynamic (92 +/- 8% in NO vs 72 +/- 7% in the control group, p < .05) and static (83 +/- 8% in NO vs 63 +/- 7% in the control group, p < 0.05) compliance and gas exchange (PaO2: 96 +/- 4% in NO vs 74 +/- 4.5% in the control group, p < 0.01; Pa/FiO2: 97 +/- 5% in NO vs 74 +/- 5% in the control group, p < 0.01) by diminishing IL-8 (66.5 +/- 4.7 pg/ml in NO versus 208 +/- 43 pg/ml in the control group, p < 0.05) release in pigs.

CONCLUSION

These results show for the first time that NO pre-treatment at the time of harvesting reduces allograft reperfusion injury in part due to its effects on IL-8 release.

Lung preservation

Better understanding of the mechanisms of ischemia-reperfusion injury, improvement in the technique of lung preservation, and the recent introduction of a new preservation solution specifically developed for the lungs have helped to reduce the incidence of primary graft dysfunction after lung transplantation. Currently, the limitation in extending the ischemic time is more often related to the increasing use of non-ideal lung donors rather than to poor lung preservation. In this review, we have focused our attention on the experimental and clinical work performed to optimize the methods of lung preservation from the time of retrieval to the period of reperfusion after graft implantation.

Estudo da fração inspirada de oxigênio na isquemia-reperfusão pulmonar em ratos

OBJETIVO: Estudar o efeito das frações inspiradas de oxigênio (FiO2) a 0,21, 0,40 e 1,00 na isquemia-reperfusão pulmonar. MÉTODOS: Foram utilizados 40 ratos Wistar, distribuídos aleatoriamente em quatro grupos. O grupo I foi o controle e, nos grupos II, III e IV, os animais foram ventilados durante a isquemia-reperfusão com FiO2 a 0,21, 0,40 e 1,00 respectivamente. O modelo utilizado foi de isquemia-reperfusão normotérmica, in situ. O tempo de isquemia foi de 30 minutos e o de reperfusão, de 10 minutos. Como parâmetros de avaliação, utilizou-se a pressão arterial média sistêmica (PAM), a relação entre a pressão parcial de oxigênio e a fração inspirada de oxigênio (PO2/FiO2), a dosagem da glutationa reduzida (GSH) e das substâncias reativas ao ácido tiobarbitúrico (TBARS) no tecido pulmonar e a relação entre o peso pulmonar úmido e o peso pulmonar seco. RESULTADOS: Os resultados mostraram que a ventilação com FiO2 a 0,21, quando comparada à ventilação com FiO2 a 0,40 e 1,00, durante o período de isquemia-reperfusão, apresentou menor diminuição da PAM, melhor relação PO2/FiO2, maior valor na medida da GSH, menor produção das TBARS e menor formação de edema pulmonar. CONCLUSÃO: A ventilação com baixa FiO2 (0,21) mostrou melhores resultados quando comparada àquelas realizadas com FiO2 mais elevadas (0,40 e 1,00) na isquemia-reperfusão pulmonar.

Impact of retrograde graft preservation in perfadex-based experimental lung transplantation

OBJECTIVE

Optimal preservation of postischemic organ function is a continuing challenge in clinical lung transplantation. Retrograde instillation of preservation solutions has theoretical advantages to achieve a homogeneous distribution in the lung due to perfusion of both the pulmonary and the bronchial circulation. Thus far, no systematic screening studies followed by in vivo large animal reevaluation including stereological analysis of intrapulmonary edema exist concerning the influence of retrograde preservation on postischemic lung function after preservation with low potassium dextran (LPD) solution (Perfadex).

MATERIALS AND METHODS

For initial screening in an extracorporeal rat model eight lungs, each, were preserved for 4 h using antegrade or retrograde preservation with LPD solution (Perfadex; PER(ant)/PER(ret)). Respiratory and hemodynamic results after reperfusion were compared to low-potassium Euro-Collins (LPEC). For systematic reevaluation, five pig lungs, each, were preserved correspondingly for 27 h, and results were compared to sham-operated control lungs. In both models, edema formation was quantified stereologically. Statistics comprised different ANOVA models.

RESULTS

In both models, use of PER(ret) resulted in significantly higher oxygenation capacity, lower inspiratory pressures, and lower amounts of intraalveolar edema as compared to PER(ant). Results of PER(ret) were not different from sham controls in the in vivo model; furthermore, a continuous retrograde elimination of blood clots from pulmonary microcirculation was noticed.

CONCLUSIONS

Retrograde application of LPD solution (Perfadex) results in significant functional and histological improvement as compared to antegrade perfusion. This innovative technique can be applied very easily in clinical practice and might be an ideal adjunct to further optimize the results after lung transplantation with LPD-based graft protection.

Lung transplantation. Lung preservation

Over the past decade, improvements in the technique of lung preservation have led to significant reduction in the incidence of ischemia-reperfusion-induced lung injury after lung transplantation. The challenge remains to improve the number of donor lungs available for transplantation. While the number of patients on the waiting list is constantly increasing, only 10% to 30% of donor lungs are currently being used for transplantation. Hence, the development of new strategies to assess, repair, and improve the quality of the lungs could have a tremendous impact on the number of transplants performed. In addition, an improved understanding of the mechanisms involved in lung preservation might help elucidate the potential link between acute lung injury and chronic graft dysfunction. In the future, genetic analysis using novel technologies such as microarray analysis will help researchers determine which genes control the injury seen in the transplantation process. Hopefully, this information will provide new insights into the mechanisms of injury and reveal potential new strategies and targets for therapies to improve lung preservation.

Beneficial effect of polyethylene glycol in lung preservation: early evaluation by proton nuclear magnetic resonance spectroscopy

BACKGROUND

Proton nuclear magnetic resonance spectroscopy can be used to measure organic molecules in biological fluids. In this study, proton nuclear magnetic resonance spectroscopy of bronchoalveolar lavage was assessed to detect cellular damage in lung transplants. Also we evaluated a polyethylene glycol solution in lung preservation.

METHODS

An isolated perfused and working pig lung was used to assess initial pulmonary function after in situ cold flush and cold storage for 6 hours in three preservation solutions: (1) Euro-Collins solution, (2) University of Wisconsin solution, and (3) low potassium solution with polyethylene glycol (PEG). Pulmonary vascular resistance and partial pressure of arterial oxygen were measured during reperfusion. Bronchoalveolar lavage was studied by proton nuclear magnetic resonance spectroscopy and a histologic study of the lungs was done at the harvest after ischemia and after reperfusion.

RESULTS

Partial pressure of arterial oxygen and pulmonary vascular resistance were significantly better in PEG compared with Euro-Collins solution (p = 0.011). Interstitial edema was significantly higher in Euro-Collins solution (2.4 +/- 0.24; p = 0.02) and University of Wisconsin solution (2.7 +/- 0.20; p = 0.0003) than PEG (2 +/- 0.16). Mitochondria scale was better in PEG (8.1 +/- 0.46) than in Euro-Collins solution (6.2 +/- 0.37; p = 0.0001) or University of Wisconsin solution (5.6 +/- 1.36; p = 0.0046). In bronchoalveolar lavage proton nuclear magnetic resonance spectroscopy spectra, lactate, pyruvate, citrate, and acetate were only detected after reperfusion, with a significantly reduced production of acetate in PEG. Pyruvate was reduced at the limit of significance in PEG versus University of Wisconsin solution.

CONCLUSIONS

Proton nuclear magnetic resonance spectroscopy seems to be a simple and suitable method for assessment of early injury to the lung transplant. In this experimental study, PEG preserved the lung better than University of Wisconsin solution and Euro-Collins solution in both the proton nuclear magnetic resonance spectroscopy study as well as the physiologic study.

Experimental lung preservation with Perfadex: effect of the NO-donor nitroglycerin on postischemic outcome

OBJECTIVE

Optimal preservation of postischemic graft function is essential in lung transplantation. Antegrade flush perfusion with modified Euro-Collins solution represents the standard technique worldwide. However, growing evidence suggests the superiority of extracellular-type Perfadex solution (Vitrolife AB, Gothenburg, Germany) over Euro-Collins solution. During ischemia and reperfusion, endogenous pulmonary nitric oxide synthesis is decreased, and therefore therapeutic stimulation of the nitric oxide pathway might be beneficial in ameliorating ischemia-reperfusion damage. However, research mainly focuses on nitric oxide supplementation of intracellular solutions, and no studies exist in which the effect of nitroglycerin on Perfadex preservation quality is evaluated.

METHODS

Eight rat lungs each were preserved with Perfadex solution with or without nitroglycerin (0.1 mg/mL) and compared with low-potassium Euro-Collins solution. Postischemic lungs were reventilated and reperfused, and oxygenation capacity, pulmonary vascular resistance, and peak inspiratory pressures were monitored continuously. Stereological analysis was used for evaluation of pulmonary edema and assessment of the vasculature. Statistics were performed by using different analysis of variance models.

RESULTS

The oxygenation capacity of the Perfadex-preserved groups was higher compared with that of the low-potassium Euro-Collins solution group (P <.03). By using nitroglycerin, flush-perfusion time was reduced, and Perfadex solution with nitroglycerin-protected lungs showed superior oxygenation capacity compared with that seen in Perfadex solution-protected organs (P <.01). Furthermore, pulmonary vascular resistance and peak inspiratory pressures were improved in the nitroglycerin group (P <.01). Stereology revealed comparable intrapulmonary edema between groups and a trend toward less vasoconstricted vasculature in Perfadex with nitroglycerin-protected lungs.

CONCLUSIONS

Perfadex solution provides superior lung preservation in terms of postischemic oxygenation capacity than Euro-Collins solution. Supplementation of the nitric oxide pathway by nitroglycerin further enhances functional outcome of Perfadex-preserved organs and might be an easily applicable tool in clinical lung transplantation.

Perfadex for clinical lung procurement: is it an advance?

BACKGROUND

Extensive laboratory experience suggested that low potassium dextran lung preservation solution (Perfadex; Medisan, Uppsala, Sweden) is superior to Euro-Collins (EC; Frusen, Hamburg, Germany), the clinical standard. The purpose of this study was to evaluate Perfadex in clinical lung transplantation.

METHODS

A retrospective analysis of the outcome of 69 consecutive lung allografts retrieved and used for transplantation was made. Donor lungs were flushed with EC in 37 patients and Perfadex in 32 patients. The evaluation measurements were quantitative chest roentgenogram score (grade 0 to 4), graft oxygenation, duration of mechanical ventilation, length of intensive care treatment, and survival.

RESULTS

The mean chest roentgenogram score was 1.55 and 1.81 for the EC group compared with 1.18 and 2.09 for the Perfadex group at 1 and 48 hours, respectively (p = 0.1 and 0.8, respectively). Arterial alveolar oxygen tension ratio was similar at 12 and 24 hours (0.61 vs 0.67; p = 0.8; and 0.64 vs 0.53; p = 0.3, respectively). The mean ventilation time was 71.2 +/- 32.3 hours versus 81.9 +/- 43.6 hours for the EC and Perfadex groups, respectively (p = 0.4). The mean intensive therapy unit stay was 3.1 +/- 2.6 days for the EC group compared with 4.1 +/- 3.9 days for the Perfadex group (p = 0.4). Death caused by primary organ failure was 5.1% for the EC group compared with 3.1% for the Perfadex group (p = 0.8).

CONCLUSIONS

There was no difference between Perfadex and EC in clinical lung preservation. This may reflect the difference between controlled laboratory environment and the real world of brain death lung injury. Further studies are required to investigate the impact of Perfadex in the long-term outcome of lung transplantation.

Ischemia-reperfusion-induced lung injury

Ischemia-reperfusion-induced lung injury is characterized by nonspecific alveolar damage, lung edema, and hypoxemia occurring within 72 hours after lung transplantation. The most severe form may lead to primary graft failure and remains a significant cause of morbidity and mortality after lung transplantation. Over the past decade, better understanding of the mechanisms of ischemia-reperfusion injury, improvements in the technique of lung preservation, and the development of a new preservation solution specifically for the lung have been associated with a reduction in the incidence of primary graft failure from approximately 30 to 15% or less. Several strategies have also been introduced into clinical practice for the prevention and treatment of ischemia-reperfusion-induced lung injury with various degrees of success. However, only three randomized, double-blinded, placebo-controlled trials on ischemia-reperfusion-induced lung injury have been reported in the literature. In the future, the development of new agents and their application in prospective clinical trials are to be expected to prevent the occurrence of this potentially devastating complication and to further improve the success of lung transplantation.

Improved results after heart-lung transplantation: a 17-year experience

OBJECTIVE

In selected patients with severe end-stage combined cardiopulmonary diseases, heart-lung transplantation (HLTx) remains the only therapeutical option for improving survival and quality of life.

PATIENTS AND METHODS

Since 1983, 51 HLTx were done at our institution. Mean patient age was 27+/-12 years with a mean donor age of 25+/-11 years. Indications for HLTx were primary pulmonary hypertension (PPH) in 49% of patients, congenital heart disease in 39%, cystic fibrosis in 6%, and repeat-HLTx in 6%. Eleven patients were younger than 14 years. Among these pediatric patients, the indications were PPH in 55% of patients, pulmonary atresia with severe pulmonary artery hypoplasia in 27%, and cystic fibrosis and cardiomyopathy with fixed pulmonary hypertension in 9% of patients each. Two patients had additional liver transplantation because of chronic aggressive virus hepatitis. For organ preservation, Euro-Collins solution (lung perfusion) and cardioplegic solution according to Bretschneider (heart perfusion) were used until 1994. The University of Wisconsin solution replaced Bretschneider's solution in 1994. Since 1996, Perfadex, a low-potassium dextran-based preservation solution, replaced Euro-Collins. All transplantations were done through a median sternotomy until 1994. Thereafter, a transverse thoracotomy was used in patients with suspected adhesions. Until 1995, cyclosporine A, azathioprine, and prednisolone were used for immunosuppression. Since then, tacrolimus replaced cyclosporine A.

RESULTS

From 1983 until 1993, perioperative mortality was 35% (6/19). From 1994 on perioperative mortality decreased to 12.5% (4/32). Early mortality was caused by graft failure (n=5), severe bleeding (n=2), multi-organ failure (n=2), and acute rejection (n=1). Cumulative survival rates were 81% after 30 days, 63% after 1 year, and 54% after 5 years, respectively. Since 1994, cumulative survival rates were markedly improved to 87% after 30 days, 81% after 6 months, and 78% after 1 year. There was no death during the first postoperative year among the 11 pediatric patients. Late death was mainly caused by obliterative bronchiolitis (OB; 76%); two patients died because of multi-organ failure or septic complications, respectively, and one patient died within the first postoperative year because of aspergillosis.

CONCLUSION

Changes in organ preservation management, surgical techniques, and immunosuppressive therapy significantly improved the short- and mid-term results after HLTx. Long-term results can only be improved in cases of successful prevention and treatment of OB.

Influence of preservation solution on early graft failure in clinical lung transplantation

The aim of this study was to assess the influence of preservation solution type and extra- or intracellular composition on the occurrence of early graft dysfunction after clinical lung transplantation. For 170 patients who underwent a single (n = 124) or bilateral (n = 46) lung transplantation in two centers in Paris between 1988 and 1999, the preservation technique applied to the donor lung was single-flush perfusion of the pulmonary artery with one of several solutions of intracellular (Euro-Collins, n = 61; University of Wisconsin, n = 24) or extracellular composition (Cambridge, n = 64; Celsior, n = 21). The early postoperative outcome of these patients was reviewed. Reimplantation edema occurred in 48% of all patients, and the overall 1-mo survival rate was 84%. No significant difference in the incidence of edema, duration of mechanical ventilation, and 1-mo survival rate was observed between the four groups or between intra- and extracellular groups. After adjustment for graft ischemic time by means of multivariate analysis, the use of extracellular preservation fluid was associated with a lower incidence of reimplantation edema without effect on 1-mo mortality. Graft ischemic time was associated with both edema occurrence and 1-mo survival rate (p = 0.02 and p = 0.01, respectively). We conclude that extracellular-type solutions are associated with better lung preservation than intracellular-type solutions in clinical transplantation.

Current strategies in lung preservation

Current methods of lung preservation allow for effective, expeditious transplantation as a treatment for end-stage pulmonary disease. However, the utilization of hypothermia, hyperkalemia, and pulmonary artery distension as a single rapid flush for perfusion is less than ideal. All these interventions result in increased pulmonary vascular resistance and suboptimal preservation of lung function. The ability to preserve lungs for longer time intervals and with less risk of tissue injury would provide significant advantages. There would be a greater likelihood that rare size or blood types could find matches by enlarging the area of organ distribution. Optimal preservation would also improve the perioperative outcomes in regard to primary graft failure and subsequently reduce the later complication of chronic rejection and graft lung dysfunction. Finally, through a better understanding of the mechanisms of lung injury during preservation and by developing means to limit the injury, it would be possible to utilize organs from donors that at this time would not be considered optimal. This would increase the donor pool without compromising the recipient's outcome.

Influence of long-term preservation with endobronchially administered perfluorodecalin on pulmonary graft function

BACKGROUND

Experimental studies demonstrated a suppression of oxygen-derived free radicals, reduced adhesion of activated neutrophils on the endothelium and an increase of de novo synthesis of surfactant during liquid ventilation with perflurocarbon. The purpose of this study was to assess the pulmonary graft function after preservation with endobronchially administered perfluorocarbon as an alternative to flush perfusion.

METHODS

Native bred pigs underwent orthotopic left lung transplantation. Donor lungs were flushed in situ with either a low-potassium dextran solution (LPD, n=6) or a perfluorochemical was administered endobronchially (PFC, n=6) and were then stored after removal for 18 hr at 4 degrees C. Pulmonary graft function was assessed after reperfusion for 5 hr by measuring pulmonary gas exchange and hemodynamics during isolated ventilation and perfusion. Tissue specimens were taken for analysis of morphology and wet/dry ratio. All values were compared to a sham-operated group (n=6).

RESULTS

Pulmonary gas exchange of the graft revealed reduced paO2 values and elevated paCO2 values in the PFC group throughout the observation period as compared with the LPD group and sham group. Endothelial alterations and fibrin exudate in the PFC group were significantly more pronounced. Lungs in the LPD group showed functional and morphological recovery close to sham group.

CONCLUSIONS

Long-term preservation with endobronchially administered perfuorocarbon is possible. Impaired pulmonary graft function and pronounced morphological alterations indicate an aggravation of the ischemic reperfusion injury after lung transplantation compared to LPD preserved lungs.

Dynamic changes in apoptotic and necrotic cell death correlate with severity of ischemia-reperfusion injury in lung transplantation

Ischemia-reperfusion (IR) injury is a major cause of organ dysfunction following lung transplantation. We have recently described increased apoptosis in transplanted human lungs after graft reperfusion. However, a direct correlation between ischemic time, cell death, and posttransplant lung function has not yet been demonstrated. We hypothesized that an increased ischemic period would lead to an increase in cell death, and that the degree and type of cell death would correlate with lung function. To investigate this, we preserved rat lungs at 4 degrees C for 20 min and 6, 12, 18, and 24 h, and then transplanted the lungs and reperfused them for 2 h. Cell viability was determined with a triple staining technique combining trypan blue, terminal deoxynucleotidyl transferase-uridine nucleotide end-labeling, and propidium iodide nuclear staining. Percentages of apoptotic and necrotic cells were calculated from total cell numbers. Following 20 min and 6 and 12 h of cold preservation, less than 2% of graft cells were dead, whereas after 18 and 24 h of cold preservation, 11% and 27% of cells were dead (p < 0.05), the majority of which were necrotic. After transplantation and reperfusion, the mode of cell death changed significantly. In the 6- and 12-h groups, approximately 30% of cells were apoptotic and < 2% were necrotic, whereas in the 18- and 24-h groups, 21% and 29% of cells, respectively, were necrotic and less than 1% were apoptotic. Lung function (Pa(O(2))) decreased significantly (p < 0.05) with increasing preservation time. The percentage of necrotic cells was inversely correlated with posttransplant graft function (p < 0.0001). The study demonstrates a significant association among cold preservation time, extent and mode of cell death, and posttransplant lung function, and suggests new potential strategies to prevent and treat IR injury.

Matrix metalloproteinases correlate with alveolar-capillary permeability alteration in lung ischemia-reperfusion injury

BACKGROUND

Matrix metalloproteinases (MMPs) are able to degrade the endothelial basal lamina and increase vascular permeability.

METHODS

In a porcine model of isolated-reperfused lung, we studied the alveolar-capillary permeability and the zymographic expression of MMP-9 and MMP-2 in the bronchoalveolar lavage fluid of lungs submitted ex vivo to ischemia in three preservation solutions [modified Euro-Collins (EC), low-potassium-dextran, modified-blood]. Twenty-two pigs were randomly divided into three groups according to the preservation solution used. One lung of each pig was rapidly reperfused and analyzed (control lung) although the other lung was reperfused and analyzed after 8 hr of ischemia (ischemic lung).

RESULTS

Alveolar-capillary permeability, evaluated by the transferrin leak index, was increased after 8 hr of ischemia compared with controls in the three groups, but was significantly higher in the modified EC group. In the EC group, after 8 hr of ischemia, both proMMP-9 and MMP-9 increased significantly (8.8- and 22-fold, respectively) compared with controls and this increase correlated with the transferrin leak index. Neither proMMP-9 nor MMP-9 increased with the other two preservation solutions. The MMP-2 increase after ischemia was smaller and was also restricted to the EC group.

CONCLUSION

MMP expression is enhanced during lung ischemia-reperfusion, especially in the presence of EC and this phenomenon correlates with the alteration of alveolar-capillary permeability.

Retrograde flush perfusion with low-potassium solutions for improvement of experimental pulmonary preservation

BACKGROUND

Optimal preservation of post-ischemic organ function is a continuing challenge in clinical lung transplantation. Retrograde instillation of preservation solutions has the theoretic advantage of achieving homogeneous distribution in the lung because of perfusing both the pulmonary and the bronchial circulation. So far, we have seen no experimental studies that include stereologic analysis of intrapulmonary edema concerning the influence of retrograde preservation on post-ischemic lung function after preservation with Perfadex and Celsior.

METHODS

In an extracorporeal rat model, we perfused 8 lungs, each, using either antegrade or retrograde perfusion technique with Celsior (CE(ant)/CE(ret)) and Perfadex (PER(ant)/PER(ret)). Results were compared with low-potassium Euro-Collins. Post-ischemic lungs were reventilated and reperfused mechanically. We continuously monitored relative oxygenation capacity (ROC), pulmonary artery pressure, flush time, and wet/dry ratio. Furthermore, we used stereologic means to evaluate edema formation. Statistics comprised different analysis of variance models.

RESULTS

Relative oxygen capacity of CE(ant)-protected lungs was superior to that of PER(ant) preservation (p = 0.05). Use of PER(ret) resulted in significantly higher ROC as compared with PER(ant) (p < 0.001) and was comparable to results obtained with CE-preservation, which was not further improved with retrograde application.

CONCLUSIONS

Celsior provides better lung preservation than does Perfadex when administered antegradely. Retrograde application of Perfadex results in significant functional improvement as compared with antegrade perfusion, which reaches the standard of Celsior-protected organs. Additional in vivo experiments in combination with ultrastructural analysis are warranted to further evaluate retrograde delivery of preservation solutions, which could be used in clinical lung transplantation to further optimize current results.

Pulmonary graft function after long-term preservation of non-heart-beating donor lungs

BACKGROUND

Critical organ shortage in lung transplantation could be attenuated by the use of non-heart-beating donor (NHBD) lungs. In addition, prolonged ischemic tolerance of the organs would contribute to the alleviation of organ shortage. The aim of this study was to investigate pulmonary graft function of NHBD lungs after long-term hypothermic storage.

METHODS

Twelve native-bred pigs (bodyweight 20 to 30 kg) underwent left lung allotransplantation. In the heart-beating donor (HBD) group, lungs were harvested immediately after cardiac arrest. In the NHBD group, lungs were subjected to a warm ischemic period of 90 minutes before harvesting. After a total ischemic time of 19 hours, pulmonary grafts in both groups were reperfused and pulmonary graft function was assessed. All values were compared with a sham-operated control group.

RESULTS

Pulmonary graft function in the HBD group was excellent. In the NHBD group, pulmonary gas exchange was impaired, but still provided good graft function compared with the excellent graft function in the HBD group. Pulmonary vascular resistance was even lower in the NHBD group. In the NHBD group, calculated intrapulmonary shunt fraction (Qs/Qt) was significantly increased compared with the sham-group. Histologic alteration and wet-to-dry ratio did not differ significantly between the HBD and NHBD group.

CONCLUSIONS

We conclude that NHBD lungs (90 minutes of warm ischemic time) have the potential to alleviate organ shortage in lung transplantation even after an extended total ischemic time.

Comparison of university of wisconsin, euro-collins, low-potassium dextran, and krebs-henseleit solutions for hypothermic lung preservation

OBJECTIVE

We sought to test the effectiveness of 4 different solutions for hypothermic rat lung preservation.

METHODS

One hundred ninety-two rats were used. The rats were divided into 4 groups, and University of Wisconsin, Euro-Collins, low-potassium dextran, or Krebs-Henseleit solution was used in each group. They were further divided into 6 subgroups of 8 rats each. The lungs were preserved at 4 degrees C for 0, 4, 6, 8, 12, or 24 hours, respectively, and lung function was studied by using a living rat perfusion model.

RESULTS

Pulmonary arterial flow decreased in each group after 4 to 6 hours of preservation; the low-potassium dextran group decreased the least and the Krebs-Henseleit group decreased the most. Pulmonary vascular resistance increased in each group after 6 hours of preservation; the Krebs-Henseleit group increased the most. Although airway pressure increased, static lung compliance and gas exchange capacity decreased after 8 hours of preservation; the Krebs-Henseleit group exhibited the worst values. Lung tissue wet/dry weight ratio increased gradually during preservation; the University of Wisconsin group exhibited the least increase. An ultrastructural study indicated the least morphologic changes in the low-potassium dextran group at 24 hours.

CONCLUSIONS

At 4 degrees C, all solutions preserved rat lungs for 4 hours with acceptable function. However, 6 hours of preservation resulted in damaged pulmonary function in some lungs, and this damage increased when preservation time was extended. The lungs preserved in low-potassium dextran solution had the best overall function, but the lungs preserved in University of Wisconsin solution had less edema.

Lung transplantation--10-year experience

OBJECTIVE

The experience at our institution with various forms of lung transplantation (heart-lung, double lung and single lung) from December 1987 to September 1998 is reviewed and discussed.

METHODS

During this decade, 282 procedures (46 heart-lungs (HLTx), 142 double lungs (DLTx) and 94 single lungs (SLTx)) have been performed in 258 patients (140 male, 118 female; age: 38 +/- 13 years). Major indications included pulmonary fibrosis (n = 73), obstructive lung disease (n = 55), cystic fibrosis (n = 48), primary pulmonary hypertension (n = 36), secondary pulmonary hypertension (majority Eisenmenger's syndrome) (n = 30), and retransplantation (n = 24).

RESULTS

Early postoperative mortality (<90 days) was 13.9% (n = 36). The 1-, 3-, and 5-year survival rates in all recipients was 77, 70 and 63%, respectively. There was no significant difference in 1-year survival rates between the different procedures (HLTx: 78%, DLTx: 77%, SLTx: 77%). Significantly better 1-year survival was achieved in patients with cystic fibrosis (89%), pulmonary fibrosis (81%), obstructive lung disease (74%), and Eisenmenger's syndrome (83%) when compared to patients with primary pulmonary hypertension (55%). Survival rates remained unchanged during this period despite expanding indications during the last years. Causes of death in 90 recipients (HLTx: n = 19, DLTx: n = 37, SLTx: n = 34) included sepsis (n = 42), obliterative bronchiolitis (n = 28), cardiac failure (n = 5), and early allograft dysfunction (n = 2). Freedom from bronchiolitis obliterans syndrome (BOS) (>stage I ISHLT) was 80% at 1 year and 45% at 5 years.

CONCLUSIONS

Lung transplantation offers a true therapeutic option with good early and midterm results. Yet, chronic graft dysfunction represents a major obstacle for long-term benefit of this procedure.

8-Br-cGMP is superior to prostaglandin E1 for lung preservation

BACKGROUND

Substitution of the nitric oxide (NO) pathway reduces ischemia/reperfusion injury after lung transplantation. 8-Br-cGMP is a membrane-permeable analogue of cGMP, the second messenger of NO. In this study, we evaluated the effect of administration of 8-Br-cGMP in the flush solution on early graft function.

METHODS

Unilateral left lung transplantation was performed in 10 weight-matched pairs of outbred pigs (24 to 31 kg). Donor lungs were flushed with 1.5 L cold (1 degree C) low potassium dextrane (LPD) solution and preserved for 20 hours. In group I (n = 5), 8-Br-cGMP (1 mg/kg) was added to the flush solution. In group II (n = 5), 8 microg/kg prostaglandin E1 (PGE1) was injected into the pulmonary artery (PA) before flush. One hour after reperfusion, the recipients' contralateral right PA and bronchus were ligated to assess graft function only. cGMP levels in the PA and pulmonary vein were measured. Extravascular lung water index (EVLWI), pulmonary vascular resistance, mean PA pressure, and gas exchange (PaO2) were assessed during a 5-hour observation period. Lipid peroxidation (thiobarbituric acid-reactive substance) and neutrophil migration to the allograft (myeloperoxidase activity) were measured at the end of the assessment.

RESULTS

In group I, a significant reduction of EVLWI (group I, 6.7 +/- 1.0 mL/kg vs group II, 10.1 +/- 0.6 ml/kg after 2 hours of reperfusion; p = 0.022), TBARS (group I, 65.6 +/- 10.0 pmol/g vs group II, 120.8 +/- 7.2 pmol/g, p = 0.0039), and MPO activity (group I, 0.8 +/- 0.1 change in optical density, (deltaOD)/mg/min vs group II, 1.7 +/- 0.3 deltaOD/mg/min, p = 0.036) was noted in comparison with group II. PaO2 levels tended to be higher in cGMP-treated animals, but the changes were not significant. Hemodynamic parameters did not differ between groups.

CONCLUSIONS

In this large animal model of lung allograft ischemia/reperfusion injury, 8-Br-cGMP as additive to the flush solution improves posttransplant lung edema, lipid peroxidation, and neutrophil migration to the allograft. This effect is not attributable to improved flush by vasodilation, as we compared 8-Br-cGMP with PGE1 given before flush in control animals.

Beneficial effects of leukocyte-depleted blood and low-potassium dextran solutions on microvascular permeability in preserved porcine lung

Modified Euro-Collins (EC) solution, a crystalloid intracellular-type solution, has been commonly used for pulmonary preservation. Several experimental studies have shown the advantages of using extracellular colloid-based solutions. The aim of this study was to compare the quality of preservation of two extracellular colloid solutions, leukocyte-depleted blood (BL) and low-potassium dextran (LPD) solutions, with that of EC solution. Lungs of 22 domestic pigs were flushed and preserved with EC (n = 8), BL (n = 7), or LPD (n = 7) solution. After harvesting, one of the lungs was reperfused immediately in an ex vivo circuit (control lungs), whereas the contralateral lung was reperfused after 8 h of cold (4 degrees C) storage (preserved lungs). Besides the lung function parameters (gas exchange, pulmonary hemodynamics and mechanics), the permeability of the endothelial-epithelial barrier was assessed by determining the transferrin leak index (TLI) using a double radioisotopic method, by measuring the alveolar/arterial protein concentration ratio, and by analyzing histopathologic changes. The functional quality (oxygenation, airway resistance, dynamic compliance [CL, dyn]) of both BL and LPD lungs was slightly but significantly superior to that of EC lungs. However, pulmonary vascular resistance was lower in BL-preserved than in EC- or LPD-preserved lungs. The TLI was increased in EC control and preserved lungs, whereas it was low in BL and LPD control lungs and did not increase after preservation. The alveolar/arterial protein concentration ratio was not different between control groups, but was increased fourfold in EC-preserved compared with BL- or LPD-preserved lungs. Finally, EC-preserved lungs presented a weight gain about twice that of BL- and LPD-preserved lungs. Morphologic analysis confirmed these results, because in the EC-preserved lungs, rupture of alveolar septa and severe alveolar edema and hemorrhage were observed, whereas BL- and LPD-preserved lungs showed a relatively well-preserved structure. The results demonstrate that both BL and LPD flush solutions preserve the endothelial-epithelial barrier better than does EC solution. Although the quality of preservation is similar, pulmonary vascular resistance is higher in LPD-preserved than in BL-preserved lungs.

Lesão pulmonar de reperfusão

A lesão de isquemia-reperfusão constitui-se em um evento fisiopatológico comum a diversas doenças da prática clínica diária. O pulmão pode ser alvo da lesão de isquemia-reperfusão diretamente, como no edema pulmonar após transplante ou na resolução de tromboembolismo; ou ainda ser atingido à distância, como nos casos de choque ou por lesão de reperfusão em intestino ou em membros inferiores, como ocorre no pinçamento da aorta, utilizado nas cirurgias de aneurisma. Dentre os mediadores envolvidos na lesão de isquemia-reperfusão, foram identificados espécies reativas tóxicas de oxigênio (ERTO), mediadores lipídicos, como a tromboxana, moléculas de adesão em neutrófilos e endotélio, fator de necrose tumoral, dentre outros. As medidas terapêuticas para a lesão de reperfusão ainda são utilizadas no plano experimental e em poucos estudos clínicos. São utilizados: antioxidantes, bloqueadores de mediadores lipídicos, inibidores da interação entre leucócito e endotélio ou substâncias que favoreçam o fluxo sanguíneo pós-isquêmico.