4th International Congress on Lung Transplantation: Organ Donation, Procurement, and Transplantation: A Comparison of Three Models

 

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Organ Donation, Procurement, and Transplantation: A Comparison of Three Models

In almost all countries in which lung transplants are performed, there is a large excess of potential recipients relative to the number of available lungs. For example, there are currently more than 71,000 patients on the national transplant waiting list in the United States; more than 3500 of these are waiting for lung transplants. The number of patients on the waiting list has been increasing steadily, and the number transplanted has remained constant at approximately 850 per year. Therefore, an increasing number of patients are dying while on the waiting list; in 1998, there were approximately 500 deaths on the lung transplant waiting list in the United States. The disparity between supply and demand for lungs for transplantation has led to examination of social and behavioral means to optimize the retrieval and utilization of available donor lungs, as well as efforts to utilize "marginal" lungs for transplantation.

The Organ Procurement and Transplant Network (OPTN): The UNOS Model

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The transplant community in the United States is joined under a national organization called UNOS, a private, not-for-profit membership corporation founded in 1984 and located in Richmond, Virginia. UNOS administers the OPTN under a contract to the United States Department of Health and Human Services (DHHS). UNOS is responsible for development of organ allocation policy, maintenance of a national network to place organs, and development of professional and public education initiatives to enhance organ donation. Since 1986, UNOS had also been the sole contractor for the United States Scientific Registry on Organ Transplantation. An important change in the most recent UNOS contract is that although UNOS has responsibility for all transplant data collection, the contract for statistical analysis of transplant data collected by UNOS was awarded to the University Renal Research and Education Association in Ann Arbor, Michigan.

UNOS members include every transplant program, organ procurement organization (OPO), and tissue typing laboratory in the United States. For administrative purposes, UNOS is divided into 11 geographic regions, but these are not necessarily linked to thoracic organ distribution. The OPOs are private, nonprofit organizations whose purpose is to procure and distribute organs in a particular geographic region. As of October 2000, there were 59 nonprofit, federally designated OPOs that facilitate organ and tissue recovery services throughout the United States.[55] These OPOs are certified by the Health Care Financing Administration and are responsible for the complex logistics of coordinating organ and tissue recovery. OPOs are either hospital-based or independent organizations. Presently, 50 of the 59 US OPOs are independent.

Eighty lung transplant programs and 88 heart-lung transplant programs are UNOS-approved. The annual number of transplants per center varies from 0 to more than 30; only 5 centers routinely do more than 30 transplants per year.

Under the current system of organ distribution in the United States, transplant candidates are placed on a national waiting list and organs are assigned to specific patients on the list rather than to a particular center. There is little or no involvement of transplant centers or physicians in deciding which organ goes to which patient. Lung transplant donors and recipients are matched on the basis of ABO group and height. Organs are offered to waiting-list patients within the donor OPO first; if an appropriate donor does not exist within the OPO, then the organ is offered to recipients in expanding, 500-mile concentric circles until an appropriate recipient is found. Organ allocation is based on a "first come, first served" system with no prioritization for medical urgency. The current system has led to regional disparities in organ allocation; for example, the median waiting time for a lung transplant is more than 600 days; however, the waiting times range from less than 200 days in some of the southeastern states to more than 800 days in Michigan.

Regional disparities in organ distribution and other factors have motivated the DHHS to take a more active role in policy related to organ distribution. Recently, DHHS issued a Final Rule, which stated that the OPTN must establish standardized minimum listing criteria based on medical factors; that status categories be established for medical urgency; and that organs be allocated according to decreasing urgency. This mandate is in contrast with the current system of lung donor organ allocation, which is not based on medical urgency. Currently, it is unclear how the American lung transplant community will respond to the government's mandate to establish an urgency-based system of organ allocation.

Organizaciòn Nacional de Transplantes: The Spanish Model

Spain leads the world in closing the gap between the demand for and supply of donor organs for transplantation. Currently, Spain boasts 33.6 organ donors per million population (compared with 16.5 per million in Europe and 24 per million in the United States), up from 14.3 per million population since 1989.[56]

The Organizaciòn Nacional de Transplantes, which coordinates activities at all transplant centers in Spain, credits their success to the following strategies, for which the government is largely responsible:

  • The efficacy of communication campaigns aimed at creating individual awareness
  • Continuous monitoring of transplant activities
  • Transplants and postsurgical medical assistance are free
  • Transplant centers with the best records obtain financial incentives.

Considerable resources have been directed toward efforts to increase organ donor awareness and to facilitate the procurement of donor organs. Spain has developed an extensive network of transplant procurement managers (TPMs), which has "professionalized" the procurement process.

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The TPMs manage all steps of the procurement process, from identification of potential donors to distribution of organs to recipients. There are between 1 and 5 TPMs per million population in Spain. TPMs work side-by-side with the transplant teams within a hospital, rather than being removed from the teams in separate OPOs. This approach facilitates a close collaboration between the procurement and transplanting teams.

Etablissement Francais de Greffe (EFG): The French System of Thoracic Organ Allocation

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In 1994, the Public Health and Social Care Law was passed in France. This law mandated creation of the EFG. The EFG is a public entity in charge of patient registrations on a national waiting list, management of the waiting list, and allocation of donor organ procurement inside or outside of France. In 1996, the French Health Secretary instituted a committee to deal with organ allocation issues. The committee consists of lawyers, hospital administrators, doctors, and other interested parties. The committee held hearings and published a final report in Novemberlocal, regional, national, and international. Priority is given to those with medical urgency, to children, and to those with a low probability of getting a graft (for example, patients with a high panel reactive antibody).

Criteria for Transplantation of Donor Lungs Should be Reevaluated

Only about 10% to 20% of lungs from organ donors are actually transplanted. Current standard criteria for acceptance of donor lungs include: age less than 55 years, clear chest x-ray, PaO2 greater than 300 mm Hg on FIO2 = 1.0; absence of chest trauma, aspiration, sepsis, or purulent bronchial secretions; and less than 20 pack/year smoking history.

However, recent studies suggest that these criteria may be stricter than necessary. For example, Gabbay and associates[59] demonstrated that the 30-day mortality rate was similar for recipients of "ideal" donor lungs (n = 66) and "marginal" donor lungs (n = 74). The group from the University of California at San Francisco (UCSF) previously demonstrated that the type II alveolar epithelial cells clear alveolar fluid and that an intact alveolar clearance mechanism is a favorable prognostic sign after lung transplantation.[60]

To extend these studies, Dr. Ware[61] studied lungs that had been turned down for transplantation. The lungs were analyzed for the degree of pulmonary edema present and the intactness of the alveolar fluid clearance mechanisms, and these measures were compared with clinical characteristics. To accomplish this, the lungs were perfused in standard fashion and sent to UCSF at 4°C. Wet:dry weight ratio was determined, the lungs were rewarmed, and alveolar fluid clearance was measured after endobronchial installation of 5% albumin.

Twenty-five lungs were evaluated. Reasons for refusal to use these organs included smoking history, abnormal chest x-ray, PaO2 less than 300 mm Hg, aspiration, and history of chest trauma. Histopathologic examination revealed normal or mildly abnormal abnormalities in 16 of 25 lungs and moderate to severe abnormalities in 9 of 25 lungs. Histologic abnormalities that were identified included respiratory bronchiolitis, bronchopneumonia, edema, and diffuse alveolar damage. Based on the wet:dry weight ratio, 30% of the lungs showed no excess pulmonary edema, and 60% showed only mild pulmonary edema. In addition, alveolar fluid clearance was intact in approximately 75% of the refused lungs. Better oxygenation in the donor correlated with a lower wet:dry weight ratio and higher alveolar fluid clearance, as expected. A normal donor chest x-ray correlated with higher alveolar fluid clearance. Alveolar fluid clearance was also highly correlated with the wet:dry weight ratio, suggesting that impaired fluid clearance increased pulmonary edema. In summary, most rejected lungs had absent or mild pulmonary edema, intact alveolar fluid clearance mechanisms, and mildly abnormal pathologic findings. These findings suggest that at least some lungs that are refused may indeed be suitable for transplantation.

Expanding the Donor Lung Pool: Split Lung for Double Lung Transplantation

Multiple strategies exist to increase the potential cadaveric lung donor pool, including presumed consent laws, use of non-heart beating donors (NHBDs), use of anencephalic donors, and split-lung techniques. Split-lung transplantation refers to dividing the left or right lung into 2 portions, each of which is transplanted into 1 hemithorax of a single recipient. The first split-lung transplant was performed in May 1993 by Dr. Couetil[62] and colleagues at the Hôpital Broussais in Paris.

To date, 27 patients have been transplanted in this manner.[62] All patients had cystic fibrosis, and 26 of the transplants were first transplants. The mean recipient age was 17 years, and 15 of the recipients were younger than 14 years of age. Twenty of the donor lungs were left lungs and 6 were right lungs. The donor left lung volume was approximately 85% of the recipient's predicted total lung capacity, and the donor right lung capacity was approximately 95% of the mean recipient total lung capacity. All of the recipient procedures utilized a clamshell incision and were performed using CPB. For left lung donors, the lung was divided into an upper lobe and a lower lobe. The upper lobe was placed into the right hemithorax of the recipient and the lower lobe was placed into the left hemithorax of the recipient. For right lung donors, the lower lobe was placed into the left hemithorax of the recipient and the combined upper lobe and middle lobe were placed into the right hemithorax of the recipient.

The procedure resulted in prolonged chest tube drainage, with a mean drainage time of approximately 2 weeks. The time on mechanical ventilation and the number of ICU days was also increased, compared with standard recipients. Ten of 27 recipients died within 3 months of transplantation (37%); reasons for death included multiorgan failure, respiratory failure, infection, and cerebral hemorrhage. Five of 17 long-term survivors have died, 4 from bronchiolitis obliterans. Five-year survival is 47%, and the functional capacity of long-term survivors is excellent. In conclusion, split-lung transplantation is useful for small patients on the waiting list who require bilateral lung transplantation before cadaver lungs become available.

Expanding the Donor Lung Pool: Use of NHBDs

If NHBD lungs could eventually be used for human lung transplantation, a large increase in the number of transplants performed would result. Dr. T. Egan[63] summarized a series of experiments conducted at the University of North Carolina, Chapel Hill, investigating the potential for use of NHBD lung as a strategy to increase the lung donor pool.[64-68] The rationale for these investigations was that the lung does not rely on perfusion for cellular respiration and that the primary function of the lung is to maintain a large viable surface area for gas exchange, which requires minimal energy.[63] Therefore, it was hypothesized that lung tissues may remain viable for extended periods of time after circulatory arrest. Their experiments have consistently shown that nonperfused lungs inflated or ventilated with 100% oxygen can demonstrate cellular viability for up to 8 hours after circulatory arrest. In current experiments, rat lungs that were ventilated with oxygen showed a two-thirds reduction in the number of dead cells compared with nonventilated lungs. In addition, adenosine triphosphate levels and total adenosine nucleotide content were significantly higher in the ventilated group, up to 12 hours after cardiac death.

 
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References

  1. Abramowicz D. Acute rejection and immunosuppressive therapy. Past issues and new developments in renal transplantation. Program of the Fourth International Congress on Lung Transplantation; September 14-15, 2000, Paris, France.
  2. Kahan BD, Rajagopalan PR, Hall M. Reduction of the occurrence of acute cellular rejection among renal allograft recipients treated with basiliximab, a chimeric anti-interleukin-2-receptor monoclonal antibody. United States Simulect Renal Study Group. Transplantation. 1999;67:276-284.
  3. Nashan B, Light S, Hardie IR, Lin A, Johnson JR. Reduction of acute renal allograft rejection by daclizumab. Daclizumab Double Therapy Study Group. Transplantation. 1999;67:110-115.
  4. Vincenti F, Kirkman R, Light S, et al. Interleukin-2-receptor blockade with daclizumab to prevent acute rejection in renal transplantation. Daclizumab Triple Therapy Study Group. N Engl J Med. 1998;338:161-165.
  5. Vincenti F, Grinyo J, Ramos E, et al. Can antibody prophylaxis allow sparing of other immunosuppressives? Transplant Proc. 1999;31:1246-1248.
  6. Palmer SM, Miralles AP, Lawrence CM, Gaynor JW, Davis RD, Tapson VF. Rabbit antithymocyte globulin decreases acute rejection after lung transplantation: results of a randomized, prospective study. Chest. 1999;116:127-133.
  7. Nicod L. Acute rejection and immunosuppressive therapy. Induction therapyin lung transplantation. Program of the Fourth International Congress on Lung Transplantation; September 14-15, 2000, Paris, France.
  8. Haney MS. Acute rejection and immunosuppressive therapy. Efficacy of interleukin-1 receptor antagonists for induction in lung transplantation. Program of the Fourth International Congress on Lung Transplantation; September 14-15, 2000, Paris, France.
  9. Keown P. Cyclosporine. Microemulsion formulation: what dosage monitoring? Program of the Fourth International Congress on Lung Transplantation; September 14-15, 2000, Paris, France.
  10. Barama A, Perner F, Beauregard-Zollinger L, Prestele H. Absorption profiling of cyclosporine therapy for de novo kidney transplantation: a prospective, randomized study comparing sparse sampling to trough monitoring. Transplantation. 2000;69:S162.
  11. Mahalati K, Belitsky P, Kiberd B, et al. Absorption profiling -- a novel method for monitoring Neoral in kidney transplantation that reduces rejection and nephrotoxicity. Transplantation. 2000;69:S114.
  12. Puhler T. Cyclosporine. Rescue therapy with inhaled cyclosporine-A in patients with obliterative bronchiolitis after lung transplantation. Program of the Fourth International Congress on Lung Transplantation; September 14-15, 2000, Paris, France.
  13. Iacono AT, Smaldone GC, Keenan RJ, et al. Dose-related reversal of acute lung rejection by aerosolized cyclosporine. Am J Respir Crit Care Med. 1997;155:1690-1698.
  14. Iacono AT, Keenan RJ, Duncan SR, et al. Aerosolized cyclosporine in lung recipients with refractory chronic rejection. Am J Respir Crit Care Med. 1996;153:1451-1455.
  15. Keenan R. Alternatives to usual triple immunosuppressive therapy. Tacrolimus as first intention treatment in lung transplantation. Program of the Fourth International Congress on Lung Transplantation; September 14-15, 2000, Paris, France.
  16. Keenan RJ, Konishi H, Kawai A, et al. Clinical trial of tacrolimus versus cyclosporine in lung transplantation. Ann Thorac Surg. 1995;60:580-584.
  17. Kur F, Reichenspurner H, Meiser BM, et al. Tacrolimus (FK506) as primary immunosuppressant after lung transplantation. Thorac Cardiovasc Surg. 1999;47:174-178.
  18. Mentzer RM Jr, Jahania MS, Lasley RD. Tacrolimus as a rescue immunosuppressant after heart and lung transplantation. The U.S. Multicenter FK506 Study Group. Transplantation. 1998;65:109-113.
  19. Halloran P, Mathew T, Tomlanovich S, Groth C, Hooftman L, Barker C. Mycophenolate mofetil in renal allograft recipients: a pooled efficacy analysis of three randomized, double-blind, clinical studies in prevention of rejection. The International Mycophenolate Mofetil Renal Transplant Study Groups. Transplantation. 1997;63:39-47.
  20. Kobashigawa JA. Mycophenolate mofetil in cardiac transplantation. Curr Opin Cardiol. 1998;13:117-121.
  21. Stern M. Alternatives to usual triple immunosuppressive therapy. Mycophenolate mofetil international trial in lung transplantation. Program of the Fourth International Congress on Lung Transplantation; September 14-15, 2000, Paris, France.
  22. Kahan BD. Efficacy of sirolimus compared with azathioprine for reduction of acute renal allograft rejection: a randomised multicentre study. The Rapamune US Study Group. Lancet. 2000;356:194-202.
  23. Kreis H, Cisterne JM, Land W, et al. Sirolimus in association with mycophenolate mofetil induction for the prevention of acute graft rejection in renal allograft recipients. Transplantation. 2000;69:1252-1260.
  24. Groth C, Backman L, Morales J, et al. Sirolimus (Rapamycin) based therapy in human renal transplantation. Transplantation. 1999;67:1036-1042.
  25. Legendre C. Future agents. Rapamycin and derivatives: experience in renal transplantation. Program of the Fourth International Congress on Lung Transplantation; September 14-15, 2000, Paris, France.
  26. Morelon E, Stern M, Kreis H. Interstitial pneumonitis associated with sirolimus therapy in renal- transplant recipients. N Engl J Med. 2000;343:225-256.
  27. Hosenpud JD, Bennett LE, Keck BM, Fiol B, Boucek MM. The Registry of the International Society for Heart and Lung Transplantation: sixteenth official report -- 1999. J. Heart Lung Transplant. 1999;18:611-626.
  28. Vinatier I. Short-term results. Predictive factors of early mortality: a multicenter retrospective study. Program of the Fourth International Congress on Lung Transplantation; September 14-15, 2000, Paris, France.
  29. Aeba R, Griffith BP, Kormos RL, et al. Effect of cardiopulmonary bypass on early graft dysfunction in clinical lung transplantation. Ann Thorac Surg. 1994;57:715-722.
  30. Gammie JS, Cheul Lee J, et al. Cardiopulmonary bypass is associated with early allograft dysfunction but not death after double-lung transplantation. J Thorac Cardiovasc Surg. 1998;115:990-997.
  31. Triantafillou AN, Pasque MK, Huddleston CB, et al. Predictors, frequency, and indications for cardiopulmonary bypass during lung transplantation in adults. Ann Thorac Surg. 1994;57:1248-1251.
  32. Szeto WY. Short-term results. Cardiopulmonary bypass does not adversely affect clinical outcome after lung transplantation. Program of the Fourth International Congress on Lung Transplantation; September 14-15, 2000, Paris, France.
  33. Van Raemdonck D. Short-term results. Reperfusion edema: impact of preservation solutions. Program of the Fourth International Congress on Lung Transplantation; September 14-15, 2000, Paris, France.
  34. Muller C, Furst H, Reichenspurner H, Briegel J, Groh J, Reichart B. Lung procurement by low-potassium dextran and the effect on preservation injury. Munich Lung Transplant Group. Transplantation. 1999;68:1139-1143.
  35. Nakamura T. Short-term results. Significance of capillary no-reflow in lung ischemia/reperfusion and protective effect of pentoxifylline. Program of the Fourth International Congress on Lung Transplantation; September 14-15, 2000, Paris, France.
  36. Maclean AA, Liu M, Fischer S, Suga M, Keshavjee S. Targeting the angiotensin system in posttransplant airway obliteration: the antifibrotic effect of angiotensin converting enzyme inhibition. Am J Respir Crit Care Med. 2000;162:310-315.
  37. Fischer S. Short-term results. Angiotensin converting enzyme inhibition by captopril: a novel approach to reduce ischemia reperfusion injury following lung transplantation. Program of the Fourth International Congress on Lung Transplantation; September 14-15, 2000, Paris, France.
  38. Cohen L, Littlefield C, Kelly P, et al. Predictors of quality of life and adjustment after lung transplantation. Chest. 1998;113:633-644.
  39. Limbos MM, Chan CK, Kesten S. Quality of life in female lung transplant candidates and recipients. Chest. 1997;112:1165-1174.
  40. McNaughton KL, Rodrigue JR, Staples FM. Health-related quality of life and symptom frequency before and after lung transplantation. Clin Transplant. 1998;12:320-323.
  41. TenVergert EM, Essink-Bot ML, Geertsma A, et al. The effect of lung transplantation on health-related quality of life: a longitudinal study. Chest. 1998;113:358-364.
  42. Maurer J. Long-term results. Renal function and systemic hypertension in lung transplant patients. Program of the Fourth International Congress on Lung Transplantation; September 14-15, 2000, Paris, France.
  43. Zaltzman JS, Pei Y, Maurer J, Patterson A, Cattran DC. Cyclosporine nephrotoxicity in lung transplant recipients. Transplantation. 1992;54:875-878.
  44. Pattison JM, Petersen J, Kuo P, Valantine V, Robbins RC, Theodore J. The incidence of renal failure in one hundred consecutive heart-lung transplant recipients. Am J Kidney Dis. 1995;26:643-648.
  45. Broekroelofs J, Navis GJ, Stegeman CA, et al. Long-term renal outcome after lung transplantation is predicted by the 1-month postoperative renal function loss. Transplantation. 2000;69:1624-1628.
  46. Soccal PM, Gasche Y, Favre H, Spiliopoulos A, Nicod LP. Improvement of drug-induced chronic renal failure in lung transplantation. Transplantation. 1999;68:164-165.
  47. Gross CR, Savik K, Bolman RM, Hertz MI. Long-term health status and quality of life outcomes of lung transplant recipients. Chest. 1995;108:1587-1593.
  48. van Den BJ, Geertsma A, van Der BW, et al. Bronchiolitis obliterans syndrome after lung transplantation and health- related quality of life. Am J Respir Crit Care Med. 2000;161:1937-1941.
  49. Loirat P. Long-term results. Quality of life. Program of the Fourth International Congress on Lung Transplantation; September 14-15, 2000, Paris, France.
  50. Shane E, Silverberg SJ, Donovan D, et al. Osteoporosis in lung transplantation candidates with end-stage pulmonary disease. Am J Med. 1996;101:262-269.
  51. Shane E, Papadopoulos A, Staron RB, et al. Bone loss and fracture after lung transplantation. Transplantation 1999;68:220-227.
  52. Liote F. Long-term results. Osteoporosis and preventive care. Program of the Fourth International Congress on Lung Transplantation; September 14-15, 2000, Paris, France.
  53. Shane E, Rodino MA, McMahon DJ, et al. Prevention of bone loss after heart transplantation with antiresorptive therapy: a pilot study. J Heart Lung Transplant. 1998;17:1089-1096.
  54. Egan T. Allocation systems for organ transplantation: international comparisons. The UNOS model. Program of the Fourth International Congress on Lung Transplantation; September 14-15, 2000, Paris, France.
  55. United Network for Organ Sharing, Richmond, Virginia. Available at: http://www.unos.org.
  56. Smith S. Introduction. Summaries From the XVIII International Congress of the Transplantation Society. Medscape Transplantation. Available at: http://transplantation.medscape.com/Medscape/CNO/2000/ICTS/Story.cfm?story_id=1579
  57. Manyalich M. Allocation systems for organ transplantation: international comparisons. The Spanish model. Program of the Fourth International Congress on Lung Transplantation; September 14-15, 2000, Paris, France.
  58. Jacquelinet C. Allocation systems for organ transplantation: international comparisons. The French EFG system. Program of the Fourth International Congress on Lung Transplantation; September 14-15, 2000, Paris, France.
  59. Gabbay E, Williams TJ, Griffiths AP, et al. Maximizing the utilization of donor organs offered for lung transplantation. Am J Respir Crit Care Med. 1999;160:265-271.
  60. Ware LB, Golden JA, Finkbeiner WE, Matthay MA. Alveolar epithelial fluid transport capacity in reperfusion lung injury after lung transplantation. Am J Respir Crit Care Med. 1999;159:980-988.
  61. Ware B. Better use of resources. Criteria for transplantation of donor lungs should be reevaluated. Program of the Fourth International Congress on Lung Transplantation; September 14-15, 2000, Paris, France.
  62. Couetil JP. Better use of resources. Split lung for double lung transplantation. Program of the Fourth International Congress on Lung Transplantation; September 14-15, 2000, Paris, France.
  63. Egan T. Better use of resources. Non-heart beating donors. Program of the Fourth International Congress on Lung Transplantation; September 14-15, 2000, Paris, France.
  64. D'Armini AM, Roberts CS, Griffith PK, Lemasters JJ, Egan TM. When does the lung die? I. Histochemical evidence of pulmonary viability after "death". J Heart Lung Transplant. 1994;13:741-747.
  65. Alessandrini F, D'Armini AM, Roberts CS, Reddick RL, Egan TM. When does the lung die? II. Ultrastructural evidence of pulmonary viability after "death." J Heart Lung Transplant. 1994;13:748-757.
  66. D'Armini AM, Tom EJ, Roberts CS, Henke DC, Lemasters JJ, Egan TM. When does the lung die? Time course of high energy phosphate depletion and relationship to lung viability after "death." J Surg Res. 1995;59:468-474.
  67. Roberts CS, Hennington MH, D'Armini AM, Griffith PK, Lemasters JJ, Egan TM. Donor lungs from ventilated cadavers: impart of a free radical scavenger. J Heart Lung Transplant. 1996;15:275-282.
  68. D'Armini AM, Lemasters JJ, Egan TM, Vigano M. Effect of perfusion pH on rat lung viability of non-heart beating donors. Eur J Cardiothorac Surg. 1997;12:787-791.
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Authors and Disclosures

Marshall I. Hertz, MD, Professor in the Division of Medicine, Pulmonary, Allergy and Critical Care at the University of Minnesota School of Medicine, Minneapolis, Minnesota

 
 
 
 
 
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