Lung procurement by low-potassium dextran and the effect on preservation injury. Munich Lung Transplant Group

Procurement of lungs from brain-dead donors

Lung transplantation is the procedure of choice in many patients with end-stage lung disease and is being performed more frequently around the world. However, there continues to be shortage of donor organs with the ever-expanding number of recipients on the waiting list, leading to liberalization of the lung donor selection criteria with increasing acceptance of marginal donors while striving for excellent results. This has placed an increasing emphasis on the technique of donor lung procurement and preservation from marginal donors. Good judgment and procurement techniques are necessary to obtain high-quality donor lungs for transplantation and optimize long-term results. This is a review of our current technique used for the procurement of the lungs from brain-dead donors.

Comparison of Acellular Solutions for Ex-situ Perfusion of Amputated Limbs

INTRODUCTION

Hypothermic ex-situ machine perfusion (MP) has been shown to be a promising alternative to static cold storage (SCS) for preservation of solid organs for transplantation and vascularized composite allotransplantation. Perfusion with blood-based perfusion solutions in austere environments is problematic due to their need for appropriate storage and short shelf life, making it impractical for military and emergency use. Acellular perfusion has been shown to be effective, but the ideal perfusate solution for MP of amputated limbs is yet to be determined. The purpose of this study is to evaluate the efficacy of alternative perfusate solutions, such as dextran-enriched Phoxilium, Steen, and Phoxilium in ex-vivo hypothermic MP of amputated limbs in a porcine model.

MATERIALS AND METHODS

Amputated forelimbs from Yorkshire pigs (n = 8) were preserved either in SCS (n = 2) at 4°C for 12 hours or machine-perfused at 10°C for 12 hours with oxygenated perfusion solutions (n = 6) at a constant flow rate. The perfusates used include modified Steen-solution, Phoxilium (PHOX), or Phoxilium enriched with dextran-40 (PHODEX). The perfusate was exchanged after 1 and 6 hours of perfusion. Machine data were recorded continuously. Perfusate samples for clinical chemistry, blood gas analysis, and muscle biopsies were procured at specific timepoints and subsequently analyzed. In this semi in-vivo study, limb replantation has not been performed.

RESULTS

After amputation, every limb was successfully transferred and connected to our perfusion device. The mean total ischemia time was 77.5 ± 5.24 minutes. The temperature of the perfusion solution was maintained at 10.18 ± 2.01°C, and perfusion pressure at 24.48 ± 10.72 mmHg. Limb weight increased by 3% in the SCS group, 36% in the PHODEX group, 25% in the Steen group, and 58% in the PHOX group after 12 hours. This increase was significant in the PHOX group compared with the SCS group. All perfusion groups showed a pressure increase of 10.99 mmHg over time due to edema. The levels of HIF-1a decreased over time in all groups except the Steen and the PHODEX group. The biomarkers of muscle injury in the perfusate samples, such as creatine kinase and lactate-dehydrogenase, showed a significant difference between groups, with highest values in the PHODEX group. No significant differences were found in the results of the blood gas analysis.

CONCLUSION

With the exception of significantly higher levels of creatine kinase and lactate dehydrogenase, MP with dextran-enriched Phoxilium provides similar results as that of the commercially available perfusates such as Steen, without the need for cold storage, and at circa 5% of the cost of the Steen solution. Further large-scale replantation studies are necessary to evaluate the efficacy of dextran-enriched Phoxilium as an alternate perfusate solution.

Review of donor and recipient surgical procedures in lung transplantation

Lung transplant remains the only durable treatment of end stage lung disease. Efficient surgical technique and preservation strategy are of critical importance in avoiding ischemia reperfusion injury and primary graft dysfunction (PGD), both associated with poorer outcomes. We present our surgical and preservation strategy for both donor and recipient procedures, including endobronchial and intracorporeal lung assessment, mediastinal dissection, lung preservation, donor pneumonectomy, back bench preparation, recipient approach, pneumonectomy, along with the bronchial, pulmonary artery, and pulmonary venous anastomoses.

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.

Hyperbranched polyglycerol as a colloid in cold organ preservation solutions

Hydroxyethyl starch (HES) is a common colloid in organ preservation solutions, such as in University of Wisconsin (UW) solution, for preventing graft interstitial edema and cell swelling during cold preservation of donor organs. However, HES has undesirable characteristics, such as high viscosity, causing kidney injury and aggregation of erythrocytes. Hyperbranched polyglycerol (HPG) is a branched compact polymer that has low intrinsic viscosity. This study investigated HPG (MW-0.5 to 119 kDa) as a potential alternative to HES for cold organ preservation. HPG was synthesized by ring-opening multibranching polymerization of glycidol. Both rat myocardiocytes and human endothelial cells were used as an in vitro model, and heart transplantation in mice as an in vivo model. Tissue damage or cell death was determined by both biochemical and histological analysis. HPG polymers were more compact with relatively low polydispersity index than HES in UW solution. Cold preservation of mouse hearts ex vivo in HPG solutions reduced organ damage in comparison to those in HES-based UW solution. Both size and concentration of HPGs contributed to the protection of the donor organs; 1 kDa HPG at 3 wt% solution was superior to HES-based UW solution and other HPGs. Heart transplants preserved with HPG solution (1 kDa, 3%) as compared with those with UW solution had a better functional recovery, less tissue injury and neutrophil infiltration in syngeneic recipients, and survived longer in allogeneic recipients. In cultured myocardiocytes or endothelial cells, significantly more cells survived after cold preservation with the HPG solution than those with the UW solution, which was positively correlated with the maintenance of intracellular adenosine triphosphate and cell membrane fluidity. In conclusion, HPG solution significantly enhanced the protection of hearts or cells during cold storage, suggesting that HPG is a promising colloid for the cold storage of donor organs and cells in transplantation.

Preservation solutions for cardiac and pulmonary donor grafts: a review of the current literature

Hypothermic preservation of donor grafts is imperative to ameliorate ischemia related cellular damage prior to organ transplantation. Numerous solutions are in existence with widespread variability among transplant centers as to a consensus regarding the optimal preservation solution. Here, we present a concise review of pertinent preservation studies involving cardiac and pulmonary allografts in an attempt to minimize the variability among institutions and potentially improve graft and patient survival. A biochemical comparison of common preservation solutions was undertaken with an emphasis on Euro Collins (EC), University of Wisconsin (UW), histidine-tryptophan-ketoglutarate (HTK), Celsior (CEL), Perfadex (PER), Papworth, and Plegisol. An appraisal of the literature ensued containing the aforementioned preservation solutions in the setting of cardiac and pulmonary transplantation. Available evidence supports UW solution as the preservation solution of choice for cardiac transplants with encouraging outcomes relative to notable contenders such as CEL. Despite its success in the setting of cardiac transplantation, its use in pulmonary transplantation remains suboptimal and improved outcomes may be seen with PER. Together, we suggest, based on the literature that the use of UW solution and PER for cardiac and pulmonary transplants, respectively may improve transplant outcomes such as graft and patient survival.

Donor management and lung preservation for lung transplantation

Although lung transplantation has become a life-saving option for patients with end-stage lung disease, this intervention is hampered by a shortage of lungs in view of the growing number of people on the waiting list. Lungs are retrieved from only a small percentage of multiorgan donors, and the transplantation and intensive-care communities have recognised the need to develop innovative methods to expand the donor pool. Advancements in lung-preservation techniques in the preretrieval and postretrieval periods have increased the pool of available donors, and novel research and discoveries in this area have steadily improved post-transplantation adverse events. This Review summarises current best practice and the latest research on intensive-care management of a potential lung donor. We also discuss lung-preservation techniques, including advancements in normothermic ex-vivo lung perfusion, and the potential for a personalised medicine approach to the organ.

Low potassium dextran is superior to University of Wisconsin solution in high-risk lung transplant recipients

BACKGROUND

The ideal solution for recovery of donor lungs remains unknown. Low potassium dextran (LPD) solution is most common, but University of Wisconsin (UW) solution is also used. The United Network for Organ Sharing (UNOS) database allows assessment of preservation solutions in a large cohort of lung transplant (LTx) patients.

METHODS

We retrospectively reviewed the UNOS data set for adult primary LTx patients (2005-2008) whose donor lungs were recovered with UW or LPD solution. Patients were stratified by UW vs LPD, and secondarily grouped by quartiles of the lung allocation score (LAS) to examine high-risk recipients. Kaplan-Meier (KM) short-term mortality (30 days, 90 days, 1 year) and rejection in the first year were examined for intervals with adequate follow-up. Cox proportional hazard regression using 11 variables examined all cause 1-year mortality.

RESULTS

Of 4,455 patients, 4,161 (93.4%) received LPD lungs and 294 (6.6%) received UW lungs, and 1,105 patients (24.8%) died during the study. There was no mortality difference based on flush solution with all patients examined together. However, patients in the upper 2 LAS quartiles (Q3: 37.8-45.4, Q4: > 45.4) receiving LPD lungs had greater 1-year survival of 81.5% vs 73.5% (p = 0.02). On multivariable analysis, flush with UW solution resulted in an increased risk of 1-year mortality (hazard ratio, 1.77. 95% confidence interval, 1.21-2.58; p = 0.003) vs LPD. Preservation solution did not affect rejection rates in the year after LTx. KM modeling demonstrated the effect of flush solution on survival (p = 0.02).

CONCLUSIONS

This study is the largest modern cohort to evaluate the effect of donor lung flush solutions on survival in adult LTx. UW solution increases the risk of 1-year mortality in high-risk LTx recipients.

Cellular electrophysiologic and mechanical evidence of superior vascular protection in pulmonary microcirculation by Perfadex compared with Celsior

OBJECTIVE

Pulmonary endothelial function is critical in posttransplant lung performance. Hyperkalemic organ preservation solutions alter vascular endothelial function through the non-nitric oxide and non-prostacyclin pathway, but the most frequently used lung preservation solutions, Perfadex (Vitrolife Sweden, Kungsbacka, Sweden) (K(+) 6 mmol/L) and Celsior (IMTIX SangStat Company, Lyon, France) (K(+) 15 mmol/L), have not been evaluated on pulmonary endothelial protection. We compared the non-nitric oxide and non-prostacyclin-mediated endothelial function in porcine pulmonary microarteries of lung preserved by Perfadex or Celsior solution at 4 degrees C for 4 hours.

METHODS

The non-nitric oxide and non-prostacyclin-mediated endothelial function was determined by measuring the membrane potential in a single pulmonary smooth muscle cell (group II, n = 6) and bradykinin-induced relaxation (group I, n = 8) in pulmonary microarteries preserved in Krebs (a, control), Perfadex (b), or Celsior (c), with inhibitors of nitric oxide and prostacyclin.

RESULTS

Membrane potential hyperpolarization decreased in IIc (4.5 +/- 0.2 mV, P < .05) but was preserved (P > .05) in IIa (6.6 +/- 0.1 mV) and IIb (6.3 +/- 0.3 mV). Resting membrane potential was depolarized in IIc (-42.8 +/- 1.3 mV) compared with IIa (-58.7 +/- 0.6 mV) and IIb (-56.7 +/- 0.9 mV) (P < .05). Hyperpolarization-associated relaxation (37.3% +/- 7.2% vs 59.7% +/- 7.7%) and sensitivity (EC(50)) (-7.29 +/- 0.13 vs -7.75 +/- 0.06 log M) to bradykinin significantly (P < .05) decreased in Ic but not in Ia and Ib.

CONCLUSION

This in vitro study simulating clinical conditions demonstrates that Perfadex preserves endothelium-dependent smooth muscle relaxation and hyperpolarization better than Celsior solution in regard to the electrophysiologic and mechanical properties observed at cellular and vascular levels. This study provides a new method at the level of basic science to evaluate the solutions for heart/lung preservation.

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.

Estudio comparativo de dos soluciones de preservación en la función inicial del trasplante bipulmonar en humanos

OBJECTIVE

Compare the influence of two preservation liquids, Euro-Collins (EC) and Perfadex (P) in the pulmonary graft function in the initial phase of lung transplant in humans.

DESIGN

Retrospective study.

SCOPE

Lung transplant unit of the ICU of a university hospital.

PATIENTS

A total of 79 patients were subjected to a transplant of both lungs. The pulmonary grafts were preserved with EC in 23 cases and with P in 56 cases.

VARIABLES OF INTEREST

Pulmonary function was assessed on admission in the intensive care unit (ICU) with the PaO2/FiO2 ratio. Mortality, graft dysfunction stay in ICU and time of mechanical ventilation were also assessed at 30 days.

RESULTS

The PaO2/FiO2 ratio was significantly greater in the P group than in the EC both on admission (p<0.006) and at 12 hours (p=0.032) in the ICU. Graft dysfunction incidence was less in group P than in EC (p<0.045). There were no differences in regards to mortality at 30 days, stay in ICU and time of mechanical ventilation between both groups.

CONCLUSION

Preservation of the pulmonary graft with P as preservation liquid compared with EC is associated with better graft function in the initial phases of transplant of both lungs and with a decrease in the incidence of graft dysfunction.

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.

Combined CMV Prophylaxis Improves Outcome and Reduces the Risk for Bronchiolitis Obliterans Syndrome (BOS) after Lung Transplantation

BACKGROUND

The benefit of cytomegalovirus (CMV) hyperimmune globuline in preventing CMV infection after lung transplantation still remains unclear. The aim of this study was to investigate the effect of combined prophylaxis using ganciclovir (GAN) and CMV hyperimmune globulin (CMV-IG) on CMV infection, CMV disease, survival and its role in preventing Bronchiolitis obliterans syndrome (BOS).

METHODS

A consecutive series of 68 CMV high-risk lung transplant recipients (D+/R-, D+/R+), who had a minimum follow-up of 1 year posttransplant were analyzed. Thirty patients (44.1%) received single GAN prophylaxis for 3 months (control group) and 38 recipients (55.9%) received GAN together with CMV-IG 7 times during the first postoperative month (study group). Median follow-up was 16.5 months in the control and 23.8 months in the study group (P = 0.54).

RESULTS

Five CMV-related deaths (16.7%) occurred in the control group (P = 0.014). Fifteen recipients suffered from CMV pneumonitis and three patients had CMV syndrome. In the control group, 13 recipients (43.3%) suffered from clinically manifested CMV disease compared to 5 (13.2%) in the study group (P = 0.007). Additionally, recipient survival was significantly better in the study group (P = 0.01). One year freedom from CMV affection was 52.1% in the control and 71.5% in the study group (P = 0.027). Three-year freedom from BOS was significantly higher in the study group (54.3% vs. 82%, P = 0.024).

CONCLUSIONS

In CMV high risk patients, additional CMV-IG administration seems to be effective to reduce CMV-related morbidity and to avoid CMV-related mortality. Reduced incidence of BOS may result from improved CMV prevention, although randomized trials are warranted.

Lung preservation solution substrate composition affects rat lung oxidative metabolism during hypothermic storage

Lungs harvested for transplantation utilize oxygen after procurement. We investigated the effects of storage solution substrate composition on pulmonary oxidative metabolism and energetics during the preservation interval. Rat lungs were harvested and stored at 10 degrees C in low-potassium dextran (LPD) solution. Groups of lungs were preserved with preservation solution containing 5mM carbon-13 ((13)C) labeled glucose or increasing concentrations of (13)C labeled pyruvate. Additional groups of rat lungs were studied with dichloroacetate (DCA) added to the pyruvate-modified preservation solutions. Oxidative metabolism (measured by (13)C-enrichment of glutamate) and adenine nucleotide levels were quantified. Increasing preservation solution pyruvate concentration augmented glutamate (13)C-enrichment up to a concentration of 32mM pyruvate. DCA further stimulated oxidative metabolism only at lower concentrations of pyruvate (4 and 8mM). ATP and ADP were not different among groups, but AMP levels were higher in the glucose group. These data suggest that altering the substrate composition of the preservation solution influences lung metabolism during allograft preservation for transplantation.

Does Perfadex Affect Outcomes In Clinical Lung Transplantation?

BACKGROUND

The use of a low-potassium-based preservation solution improves gas exchange in experimental models of lung transplantation. However, its efficacy in reducing the incidence of primary graft dysfunction (PGD) and improving patient outcomes in the clinical setting is controversial.

METHODS

In this study we measured: oxygenation index (OI); International Society of Heart and Lung Transplantation (ISHLT) PGD grades; extubation times; intensive care unit (ICU) and hospital length of stay; 30-day, 90-day and 1-year survival rates; and bronchiolitis obliterans syndrome (BOS)-free survival. We compared 115 consecutive (2001 to 2004) lung recipients who received allografts preserved with Perfadex, a low-potassium dextran (LPD) solution, and compared the results with the previous 116 consecutive (1999 to 2001) lung recipients who received allografts preserved with modified Euro-Collins (MEC) solution. Recipients were classified as having severe PGD (ISHLT Grade III) if the lowest arterial oxygenation (P) to fraction of inspired oxygen (F) (P/F ratio) within 48 hours post-transplantation was <200.

RESULTS

Baseline characteristics of the 2 cohorts were similar except for recipient age (LPD 53.5 vs MEC 49.9 years; p = 0.03). There were no differences in donor age, gender, category of transplant, indication for transplant, use of cardiopulmonary bypass or pre-operative pulmonary artery pressures. When gas-exchange parameters were measured upon arrival to the ICU (T0), at 24 hours post-transplant (T24) and at 48 hours post-transplant (T48), the only significant finding was that the incidence of ISHLT Grade III PGD at T24 was lower in the LPD group compared with the MEC group (8% vs 20%, p = 0.03). The incidence of severe PGD at other timepoints was not statistically different (LPD vs MEC: T0, 17% vs 26%; T0 to T48, 25% vs 31%). Both groups had similar extubation rates at 48 hours post-transplant (LPD 64% vs MEC 67%). The 30-day survival (LPD 93% vs MEC 95%), 90-day survival (LPD 89% vs MEC 89%), 1-year patient survival (LPD 80% vs MEC 77%) and 1-year BOS-free survival (LPD 70% vs MEC 74%) were not statistically different.

CONCLUSIONS

Lung preservation with LPD as compared with MEC does not improve early gas exchange or impact 90-day and 1-year mortality. Continued investigation into lung preservation solution composition is necessary to reduce the incidence of PGD.

[Lung transplantation in cystic fibrosis: perioperative mortality]

OBJECTIVE

To determine the incidence and causes of perioperative mortality following lung transplant for cystic fibrosis.

PATIENTS AND METHODS

We analyzed the cases of 57 patients. Fifty-five patients received double lung transplants, 1 received a heart-double lung transplant, and 1 received a combined double lung and liver transplant. Information related to the organ donor, recipient, lung graft, and early postoperative period was gathered. Perioperative mortality was defined as death resulting from anesthesia or surgery regardless of how many days had passed. The Kaplan-Meier method was used to analyze survival. A Cox logistic regression model was used to determine variables affecting mortality.

RESULTS

Survival was 83.7% at 1 year after transplantation, 77.3% at 2 years, and 66.9% at 5 years. Five (8.7%) patients died as a result of anesthesia or surgery. A ratio of PaO2 to inspired oxygen fraction (FiO2) less than 200 mm Hg in the early postoperative period was observed in 8 (14%) patients. Primary graft failure occurred in 4 patients, due to pneumonia in 2 and to biventricular dysfunction in 2. Three of those patients died. Two patients with PaO2/FiO2 greater than 200 mm Hg died after surgery, one from septic shock due to Pseudomonas cepacia and the other from massive cerebral infarction. PaO2/FiO2 upon admission to the recovery care unit was the only variable significantly associated with perioperative mortality in the logistic regression model (P=.0034).

CONCLUSIONS

The only factor significantly related to perioperative mortality in patients receiving transplants for cystic fibrosis was PaO2/FiO2 upon admission to the recovery unit.

Inhalative Pre-Treatment of Donor Lungs Using the Aerosolized Prostacyclin Analog Iloprost Ameliorates Reperfusion Injury

BACKGROUND

Lung transplantation is effective for end-stage pulmonary disease, but its successful application is still limited by organ shortage and sub-optimal preservation techniques. Therefore, optimal allograft protection is essential to reduce organ dysfunction, especially in the early post-operative period. Intravenous prostanoids are routinely used to ameliorate reperfusion injury. However, the latest evidence suggests similar efficacy using inhaled prostacyclin. Thus, we evaluated the impact of donor pre-treatment using the prostacyclin analog, iloprost, on post-ischemic function of Perfadex-protected allografts.

METHODS

In Group 1, 5 pig lungs were preserved with Perfadex (PER group) solution and stored for 27 hours. In Group 2, 100 microg of iloprost was aerosolized over 30 minutes using a novel mobile ultrasonic nebulizer (Optineb) before identical organ harvest (PER-ILO group). After left lung transplantation and contralateral lung exclusion, hemodynamic variables, Po2/Fio2 and dynamic compliance were monitored for 6 hours and compared with sham-operated controls. Pulmonary edema was determined stereologically and by wet-to-dry (W/D) weight ratio. Statistical assessment included analysis of variance (ANOVA) with repeated measures.

RESULTS

Dynamic compliance and pulmonary vascular resistance (PVR) were superior in iloprost-treated compared with untreated organs (p < 0.05), whereas oxygenation was comparable between groups. W/D ratio revealed a significantly smaller amount of lung water in PER-ILO organs (p = 0.048), whereas stereologic data showed a trend toward less intra-alveolar edema.

CONCLUSIONS

Endobronchial application of iloprost in donor lungs before Perfadex preservation decreases post-ischemic edema and significantly improves lung compliance and vascular resistance. This innovative approach is easily applicable in the clinical setting and offers a new strategy for improvement of pulmonary allograft preservation.

Characterizing lung metabolism with carbon-13 magnetic resonance spectroscopy in a small-animal model: evidence of gluconeogenesis during hypothermic storage

Experimental evidence suggests storing lungs inflated with oxygen and with oxidizable substrate improves results of lung transplantation. Glucose is included in the low-potassium-dextran (LPD) solution Perfadex to achieve this goal. The authors hypothesized that other substrates might be more effective. Rat lungs were stored for 6 or 24 hr in LPD solution with the following carbon-13--labeled substrates: 5 mM glucose (Perfadex group), 32 mM pyruvate (pyruvate group), or both (combination group). Metabolism was assessed by magnetic resonance spectroscopy. Small amounts of exogenous glucose were oxidized in the Perfadex group. In contrast, exogenous pyruvate was the major substrate oxidized in the pyruvate and combination groups (P<0.01 vs. Perfadex). Carbon-13--labeled glucose and glycogen were detected in the pyruvate group, suggesting that gluconeogenesis and glycogen synthesis occur in glucose-deprived lungs. Lungs for transplantation metabolize substrates through both anabolic and catabolic pathways. These reactions may be important in designing improved solutions for lung preservation.

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.

Pyruvate-Modified Perfadex Improves Lung Function After Long-Term Hypothermic Storage

BACKGROUND

Lungs harvested for transplantation are stored while inflated with oxygen, which can serve to support oxidative metabolism. However, strategies aimed at increasing graft metabolism during storage have received little attention. In this study, we added pyruvate to the preservation solution Perfadex and measured the effects on oxidative metabolism and reperfusion lung function.

METHODS

Rat lungs were stored for 6 and 24 hours in low-potassium dextran solution at 10 degrees C containing either 5 mmol/liter uniformly carbon-13 (U-(13)C) labeled glucose (Perfadex), 32 mmol/liter 3-(13)C pyruvate (pyruvate), or both (combined). Oxidation of exogenous substrates was measured as the incorporation of (13)C into tricarboxylic acid cycle intermediates by magnetic resonance spectroscopy. Additional groups of lungs with each substrate modification were preserved for 6 or 24 hours and then reperfused.

RESULTS

Enrichment of tricarboxylic acid cycle intermediates was low in the Perfadex group (9% at 6 hours and 32% at 24 hours of storage, respectively). In contrast, enrichment was significantly increased in both the pyruvate group (50% and 59%, respectively) and combined group (39% and 54%, respectively) compared with the Perfadex group (p<0.01). Graft function was excellent after 6-hour storage in all groups. All lungs stored for 24 hours exhibited inferior lung function, but oxygenation, pulmonary artery pressures, and airway pressures in the combined group were significantly improved compared with the Perfadex group (p<0.05).

CONCLUSIONS

Preservation solution substrate composition influences graft metabolism during storage. The addition of pyruvate to Perfadex increases metabolism during storage and improves reperfusion lung function.

[Improvements in lung preservation: 3 years' experience with a low-potassium dextran solution]

OBJECTIVE

Lung preservation quality is a crucial factor in the success of a lung transplant. In October 2000 we stopped using Euro-Collins (EC) lung preservation solution and began using a low potassium dextran solution (Perfadex [PER]). The objective of the present study was to assess outcome with the 2 solutions.

MATERIAL AND METHODS

We analyzed the results of 68 lung transplants in which PER was used and compared the results with those of a historical control group consisting of the same number of transplants in which EC was used.

RESULTS

There were no significant differences in the ages and diagnoses of the recipients in the 2 groups. Waiting list time was longer in the PER group. The most frequent cause of donor death in the EC group was craniocerebral trauma (62%), whereas in the PER group it was cerebral hemorrhage (54%). In the PER group more double lung transplants were performed than in the EC group (78% and 53% respectively; P=.002). There were no differences in the use of extracorporal circulation or ischemia time between the 2 groups. Early graft function, based on the patient's oxygenation index (ratio of PaO2 to inspired oxygen fraction [FiO2]) on arrival at the intensive care unit, was similar in the 2 groups. The incidence of severe graft failure (PaO2/FiO2<150 mm Hg) was significantly lower in the PER group than in the EC group (16% and 37% respectively; P=.01). No significant differences in hours of mechanical ventilation or postoperative mortality between the 2 patient series were found.

CONCLUSIONS

Use of the newer lung preservation solution --PER-- led to a 50% lower incidence of severe ischemia-reperfusion graft injury during the early recovery from lung transplantation.

Donor pretreatment using the aerosolized prostacyclin analogue iloprost optimizes post-ischemic function of non-heart beating donor lungs

BACKGROUND

Ischemia-reperfusion injury accounts for one-third of early deaths after lung transplantation. To expand the limited donor pool, lung retrieval from non-heart beating donors (NHBD) has been introduced recently. However, because of potentially deleterious effects of warm ischemia on microvascular integrity, use of NHBD lungs is limited by short tolerable time periods before preservation. After intravenous prostanoids are routinely used to ameliorate reperfusion injury, the latest evidence suggests similar efficacy of inhaled prostacyclin. Therefore, the impact of donor pretreatment with the prostacyclin analogue iloprost on postischemic NHBD lung function and preservation quality was evaluated.

METHODS

Asystolic pigs (5 per group) were ventilated for 180 minutes of warm ischemia (Group 2). In Group 3, 100 microg iloprost was aerosolized during the final 30 minutes of ventilation with a novel mobile ultrasonic nebulizer. Lungs were then retrogradely preserved with Perfadex and stored for 3 hours. After left lung transplantation and contralateral lung exclusion, hemodynamics, rO2/FiO2, and dynamic compliance were monitored for 6 hours and compared with sham-operated controls (Group 1). Pulmonary edema was determined both stereologically and by wet-to-dry weight ratio (W/D). Statistics comprised analysis of variance with repeated measures and Mann-Whitney test.

RESULTS

Flush preservation pressures, dynamic compliance, inspiratory pressures, and W/D were significantly superior in iloprost-treated lungs, and oxygenation and pulmonary hemodynamics were comparable between groups. Stereology revealed a trend toward lower intraalveolar edema formation in iloprost-treated lungs compared with untreated grafts.

CONCLUSIONS

Alveolar deposition of Iloprost and NHBD lungs before preservation ameliorates postischemic edema and significantly improves lung compliance. This easily applicable innovation approach, which uses a mobile ultrasonic nebulizer, offers an important strategy for improvement of pulmonary preservation quality and might expand the pool of donor lungs.

Graft ischemic time and outcome of lung transplantation: a multicenter analysis

RATIONALE

The effect of graft ischemic time on early graft function and long-term survival of patients who underwent lung transplantation remains controversial. Consequently, graft ischemic time has not been incorporated in the decision-making process at the time of graft acceptance.

OBJECTIVES

To investigate the relationship between graft ischemic time and (1) early graft function and (2) long-term survival after lung transplantation.

MEASUREMENTS AND MAIN RESULTS

The data from 752 patients who underwent single lung transplantation (n = 258), bilateral lung transplantation (n = 247), and heart-lung transplantation (n = 247) in seven French transplantation centers during a 12-year period were reviewed. Independent data quality control was done to ensure the quality of the collected variables. Mean graft ischemic time was 245.8 +/- 96.4 minutes (range 50-660). After adjustment on 11 potential confounders, graft ischemic time was associated with the recipient Pa(O2)/FI(O2) ratio recorded within the first 6 hours and with long-term survival in patients undergoing single or double lung transplantation but not in patients undergoing heart-lung transplantation. The relationship between graft ischemic time and survival appears to be of cubic form with a cutoff value of 330 minutes. These results were unaffected by the preservation fluid employed.

CONCLUSIONS

The results of this large cohort of patients suggest a close relationship between graft ischemic time and both early gas exchange and long-term survival after single and double lung transplantation. Such relationship was not found in patients undergoing heart-lung transplantation. The expected graft ischemic time should be incorporated in the decision-making process at the time of graft acceptance.

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.

Evaluation of eight preservation solutions for endothelial in situ preservation

BACKGROUND

Non-heart-beating donors (NHBDs) have the potential to reduce the increasing numbers of patients on kidney and liver graft waiting lists. One problem observed with kidneys obtained from NHBDs is the endothelial injury seen on protocol core biopsies after implantation. We postulate that this is caused by a combination of warm ischemia, cold ischemia, and hypertonic citrate during in situ preservation (ISP) rather than hypothermic machine preservation. Our aim was to optimize ISP methods to preserve endothelial structure and function.

METHODS

An animal model of ISP was used to compare the ability of eight different preservation solutions to protect mammalian vascular tissue exposed to a combination of warm and cold ischemia. Smooth muscle contractile function and endothelial dependent relaxation (nitric oxide production) were determined using an organ bath method.

RESULTS

Bretchneider's HTK solution preserved the ability of endothelial tissue to relax vascular tissue in response to acetylcholine (91% relaxation vs. 17% saline control; ANOVA, P<0.001); in stark contrast, Marshall's solution performed no better than saline (15% relaxation vs. 17% saline control, P=NS). UW solution (80%) and a derivative lacking the starch colloid (70%) were comparable with HTK. Belzer-MPS (55%), Celsior (57%), and Perfadex (44%) showed a roughly equivalent level of endothelial preservation. Electron microscopy confirmed an anatomical loss of structure correlating with loss of function.

CONCLUSIONS

ISP requires a large volume of fluid to be pumped at high flow rates. In this model, HTK retained a powerful ability to preserve endothelial structure and function during warm ischemia.

Endothelium-dependent relaxation of canine pulmonary artery after prolonged lung graft preservation in University of Wisconsin solution: role of L-arginine supplementation

BACKGROUND

The University of Wisconsin (UW) solution has been demonstrated to enhance pulmonary allograft preservation. Endothelial nitric oxide (NO) production has been shown to be significantly impaired after ischemia and reperfusion (I/R) injury. The present experiments aimed to determine the protective effects of pulmonary endothelium-dependent function by using supplemental NO in University of Wisconsin (UW) solution following prolonged lung graft preservation.

METHODS

Thirty-six healthy mongrel dogs underwent thoracotomy to expose the left lung. In addition to a group given UW solution (n = 4), 100 micromol/liter l-arginine, (n = 7), 100 micromol/liter N(G)-monomethyl-l-arginine (l-NMMA n = 7) and 1.0 micromol/liter 3-morpholinosydnonimine (SIN-1, n = 18 respectively, were added to UW solution, and infused from the aortic root and pulmonary artery to the pulmonary vein. The perfused lung was then allowed to inflate to its maximum volume for 24-hour oxygenated preservation in each supplemented condition of UW solution at 4 degrees C. In the SIN-1 group, the preservation period was further divided into 8 hours and 16 hours, respectively. Rings of the third-order pulmonary artery of the inflated lung were then suspended in organ chambers to measure isometric force.

RESULTS

Endothelium-dependent relaxation (EDR) to acetylcholine, adenosine diphosphate and sodium fluoride of the pulmonary rings in the l-arginine group was significantly preserved compared with UW-solution-only group. The l-NMMA group showed significant EDR impairment after 24-hour preservation compared with the UW solution group. Similar to the l-arginine group, the SIN-1 group showed significant EDR protection with 8-hour preservation, but not with 24-hour preservation. In contrast, EDR to calcium ionophore A23187 showed no EDR changes after 24-hour preservation in any of the supplemented groups.

CONCLUSIONS

Supplemental l-arginine in UW solution ameliorates impaired pulmonary EDR following prolonged lung preservation of up to 24 hours.

Plasmolemmal potassium gradient does not affect lung protection by an ATP-regulated potassium channel opener

BACKGROUND

We have previously shown that metabolic arrest induced with ATP-regulated potassium channel openers (PCOs) can improve lung preservation by adding Aprikalim (a PCO, Rhone-Poulene Roher) to modified Euro-Collins solution for pulmonary artery flush. Because the membrane hyperpolarizing effects of a PCO potentially competes with the depolarizing effects of a hyperkalemic solution, this study evaluated the effects of the potassium gradient on PCO-mediated lung protection.

STUDY DESIGN

Twenty rabbits underwent lung protection in four groups. Group 1 underwent harvest and reperfusion as a "no ischemia" control. Groups 2, 3, and 4 underwent harvest followed by 18 hours of cold ischemic storage before reperfusion. Groups 1 and 4 received Euro Collins as the pulmonary flush at induction of ischemia. Group 2 received Euro Collins plus Aprikalim (100 microM); and group 3 received lactated Ringer's plus Aprikalim. After ischemic storage, the lungs were reperfused with autologous blood for 2 hours. Every 30 minutes, the lungs were given a 10-minute 100% fractional inspired oxygen (F(i)O(2)) challenge to measure maximal gas exchange as an indication of graft function.

RESULTS

Repeated measures ANOVA showed Aprikalim improved graft function after 18 hours of cold ischemia (p < 0.0001). No significant differences were found when Aprikalim was used in either Euro-Collins (group 2) or lactated Ringer's (group 3) solution.

CONCLUSIONS

The ability of the PCO Aprikalim to preserve gas exchange in a model of hypothermic pulmonary ischemia-reperfusion injury was not affected by the plasmolemmal potassium gradient. This is consistent with recent findings in myocardial protection studies that the protective effects of PCOs may be intracellular.

Lung Retrieval from Non-Heart-Beating Donors: First Experience with an Innovative Preservation Strategy in a Pig Lung Transplantation Model

OBJECTIVE

Lung transplantation is limited by the scarcity of donor organs. Lung retrieval from non-heart-beating donors (NHBD) might extend the donor pool and has been reported recently. However, no studies in NHBD exist using the novel approach of retrograde preservation with Perfadex solution.

METHODS

Heparinized asystolic pigs (n = 5, 30-35 kg) were ventilated for 90 min. The lungs were retrogradely preserved with Perfadex solution and stored inflated at 4 degrees C for 3 h. Left lung transplantation in the recipient was followed by exclusion of the right lung. Results were compared to sham-operated animals. Oxygenation, hemodynamics and dynamic compliance were monitored for 4 h. Infiltration of polymorphonuclear cells (PMNs) and stereological quantification of alveolar edema was performed. Statistical analysis comprised Kruskal-Wallis and Mann-Whitney tests and ANOVA analysis with repeated measures.

RESULTS

No mortality was observed. During preservation, continuous elimination of blood clots via the pulmonary artery venting site was observed. Oxygenation and compliance were similar between groups, but sham controls showed significantly lower pulmonary vascular resistance. Stereological quantification revealed higher volume fractions of intra-alveolar edema in NHBD grafts, while PMN infiltration was comparable to sham controls.

CONCLUSIONS

Use of NHBD lungs results in excellent outcome after 90 min of warm ischemia followed by retrograde preservation with Perfadex solution. This novel approach can optimize lung preservation by eliminating clots from the pulmonary circulation and might clinically be considered in brain-dead organ donors who become hemodynamically unstable prior to organ harvest. Further trials with longer warm and cold ischemic periods are necessary to further elucidate this promising approach to donor pool expansion.

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.

Influence of preservation solution on early lung function (Euro-Collins vs Perfadex)

BACKGROUND

This clinical study was performed to evaluate the efficiency of 2 different preservation solutions (Euro-Collins [EC] vs Perfadex [P]) on organ function in human lung transplantation.

METHODS

The donor lungs for 46 patients were flushed either with EC solution (25 cases, EC group) or Perfadex (21 cases, P group). Transplant function was assayed using PaO2/FiO2 ratio after transplantation upon intensive care unit (ICU) arrival and at 12 and 24 hours later (T1, T2, and T3, respectively). We also compared the duration of mechanical ventilatory support and ICU stay.

RESULTS

The PO2/FiO2 ratio was significantly better in the P than EC group at T1, T2, and T3. The duration of mechanical ventilatory support and ICU stay were lower also in P group, whereas age, sex, aetiology of lung disease, donor, PaO2/FiO2 ratio, and ischemia time did not show differences between the 2 groups.

CONCLUSIONS

Our data on graft function tend to confirm better graft preservation using the P preservation solution.

Effects of rewarming on nuclear factor-kappaB and interleukin 8 expression in cold-preserved alveolar epithelial cells

BACKGROUND

Nuclear factor-kappaB (NF-kappaB) and interleukin (IL)-8 play important roles in the pathophysiology of acute lung injury after lung transplantation. Because alveolar epithelium is one of the most important sites at which IL-8 production takes place after reperfusion of donor lungs, we examined the effects of cold/rewarming on NF-kappaB and IL-8 expression in alveolar epithelial cells.

METHODS

A549 cells were preserved at 4 degrees C for 5 hr and then rewarmed for up to 20 hr. NF-kappaB was analyzed by electrophoretic mobility shift assay. IL-8 mRNA expression was examined by reverse transcription-polymerase chain reaction. IL-8 concentration in the cell culture medium after rewarming was measured by enzyme-linked immunosorbent assay.

RESULTS

NF-kappaB was increased in the nuclear extracts as early as 30 min after rewarming. There was a marked increase in the IL-8 mRNA expression at 1 and 3 hr after rewarming. IL-8 concentration in the cell culture medium was progressively increased during 20 hr following rewarming. The cell culture medium inhibited apoptosis of neutrophils significantly. The cold/rewarming-induced IL-8 production was reduced to approximately 50% by introducing an antisense oligonucleotide for the p65 subunit of NF-kappaB and by treatment with N-acetyl-leucinyl-leucinyl-norleucinal and pyrrolidine dithiocarbamate. The effect of dexamethasone treatment was dose dependent (reduced to approximately 30% at 10-5 M dexamethasone).

CONCLUSIONS

Our results indicate that rewarming of cold-preserved alveolar epithelial cells itself may be an important initiator of the inflammatory cascades, including NF-kappaB activation and IL-8 release. Inhibition of NF-kappaB would be worth trying to control unnecessary IL-8 production and the inflammatory response in the donor lungs.

Nitric oxide during perfusion improves posttransplantation function of non- heart-beating donor lungs

BACKGROUND

We attempted to determine in a pig model whether 20 ppm of nitric oxide (NO) during perfusion ameliorates warm ischemic lung injury in the non-heart-beating donor (NHBD), thereby improving function with longer warm ischemia.

METHODS

Lungs were retrieved from three groups (n=6): 1 hr (NHBD(1)) and 2 hr with and without NO (NHBD(2)NO, NHBD(2)) after hypoxic death. For assessment and preservation, left lungs were ventilated with 100% oxygen (NHBD(2)NO with added NO) and perfused for 20 min with neutrophil-depleted, deoxygenated blood in Perfadex solution. Pulmonary vascular and airway pressures and blood flow were measured with pulmonary venous blood gases. Perfusion temperature was reduced to 18 degrees C prior to storage at 4 degrees C before transplantation.

RESULTS

NO during perfusion significantly improved posttransplantation pulmonary venous oxygenation (NHBD(1) [mean +/- SD] 51+/-14 kPa, NHBD(2) 54+/-16 kPa, and NHBD(2)NO 61+/-6 kPa; P=0.01) and airway pressures (NHBD(1) 30.8+/-3.5, NHBD(2) 32.5+/-5.6, NHDB(2)NO 29.4+/-5.3; P=0.0001). NO significantly improved pulmonary vascular resistance (excluding the initial cold-induced vasoconstricted reperfusion period): NHBD(1) 19+/-9 Wood units, NHBD(2) 28+/-25 Wood units, NHDB(2)NO 16+/-10 Wood units, P=0.029. Neutrophil uptake was significantly lowered by NO: NHBD(1) 0.6+/-1.4*10(9) minute-1, NHBD(2) 1.2+/-1.0*10(9) minute-1, NHBD(2)NO 0.4+/-0.9*10(9) minute-1 (P=0.029).

CONCLUSIONS

This technique satisfactorily assesses and preserves the non-heart-beating lung. NO during preservation reverses the slight deterioration seen when increasing warm ischemia from 1 to 2 hr, significantly improving transplant oxygenation, vascular resistance, and airway pressures. This may be a result of the observed significant reduction in neutrophil sequestration.

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.

Pulmonary preservation studies: effects on endothelial function and pulmonary adenine nucleotides

BACKGROUND

Lung transplantation is an effective therapy plagued by a high incidence of early graft dysfunction, in part because of reperfusion injury. The optimal preservation solution for lung transplantation is unknown. We performed experiments using an isolated perfused rat lung model to test the effect of lung preservation with three solutions commonly used in clinical practice.

METHODS

Lungs were retrieved from Sprague-Dawley rats and flushed with one of three solutions: modified Euro-Collins (MEC), University of Wisconsin (UW), or low potassium dextran and glucose (LPDG), then stored cold for varying periods before reperfusion with Earle's balanced salt solution using the isolated perfused rat lung model. Outcome measures were capillary filtration coefficient (Kfc), wet-to-dry weight ratio, and lung tissue levels of adenine nucleotides and cyclic AMP.

RESULTS

All lungs functioned well after 4 hr of storage. By 6 hr, UW-flushed lungs had a lower Kfc than LPDG-flushed lungs. After 8 hr of storage, only UW-flushed lungs had a measurable Kfc. Adenine nucleotide levels were higher in UW-flushed lungs after prolonged storage. Cyclic AMP levels correlated with Kfc in all groups.

CONCLUSIONS

Early changes in endothelial permeability seemed to be better attenuated in lungs flushed with UW compared with LPDG or MEC; this was associated with higher amounts of adenine nucleotides. MEC-flushed lungs failed earlier than LPDG-flushed or UW-flushed lungs. The content of the solution may be more important for lung preservation than whether the ionic composition is intracellular or extracellular.

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.

Primary graft failure following lung transplantation: predictive factors of mortality

STUDY OBJECTIVES

To assess incidence, outcome, and early predictors of mortality for patients with primary graft failure (PGF) following lung transplantation (LTx), and to develop an injury severity score able to accurately predict ICU mortality for these patients.

DESIGN

Retrospective cohort analysis.

SETTING

Two LTx centers in Paris.

PATIENTS

Two hundred fifty-nine patients who underwent LTx over a 12-year period.

MEASUREMENTS AND RESULTS

One hundred thirty-one patients (50.6%) met PGF criteria: radiographic graft infiltrate within the first 3 days following LTx associated with gas exchange impairment (PaO(2)/fraction of inspired oxygen ratio < 300 mm Hg). This syndrome was associated with an increased duration of mechanical ventilation (9.1 +/- 1 days vs 3.1 +/- 0.6 days, mean +/- SD; p < 0.001) and ICU mortality (29% vs 10.9%; p < 0.01). The patients with PGF were randomly assigned to developmental (n = 85) and validation (n = 46) samples. Using logistic regression analysis, four variables were found associated with ICU mortality in these patients: age, degree of gas exchange impairment, graft ischemic time, and severe early hemodynamic failure. An ischemia/reperfusion injury severity score was derived using these four variables. Model calibration was good in the developmental and validation samples, as was model discrimination (area under receiver operating characteristic curves, 0.93 and 0.85, respectively).

CONCLUSION

PGF following LTx is a frequent event, with significant ICU morbidity and mortality. We demonstrate that four simple factors allow prediction of ICU mortality with good accuracy.