Upgrading Donor Lung Quality To Improve Availability
Donor Lung Transplant
By performing simple clinical maneuvers to improve donor lung quality as part of the San Antonio Lung Transplant (SALT) protocol, researchers significantly increased the number of available donor lungs and transplant procedures without compromising recipient pulmonary function, length of hospital stay or survival.
The study appears in the second issue for September 2006 of the American Journal of Respiratory and Critical Care Medicine, published by the American Thoracic Society.
Implemented in 2001, the SALT donor-management protocol applied to all potential organ donors evaluated for candidacy by the Texas Organ Sharing Alliance in San Antonio during the study until 2005. Its purpose was to increase the lung procurement rate without adversely affecting the overall survival rate of lung transplant recipients.
Luis F. Angel, M.D., of the Division of Pulmonary and Critical Care Medicine at the University of Texas Health Science Center at San Antonio, and 12 associates reviewed data from 711 potential lung donors listed between September 1, 1997, and August 31, 2005.
During the four-year SALT donor management period studied, 121 lungs were transplanted, as contrasted to 53 during the prior four years before the management program started.
"Of the 98 actual lung donors during the protocol (SALT) period, 53 had initially been considered poor donors," said Dr. Angel. "These donors ultimately provided 64, or 53 percent, of the 121 lung transplants. The type of donor was not associated with significant differences in recipients' 30-day and 1-year survival rates or any clinical measures of adequate graft function."
According to the study, the problem of donor lung availability is a very serious one. In 2005, nearly 3,000 patients were on a national waiting list for lung transplantation. However, only 35 percent of these patients received transplants, while 10 percent died awaiting an organ. Approximately half of the listed patients were on the list more than two years before receiving their transplant.
The authors noted that this trend worsens each year. The number of new additions to the transplant list is nearly double the number of patients who receive lungs.
According to the SALT lung management protocol, donor organs from brain dead patients (average age 36) were classified according to lungs' oxygenation ability, whether lung tissue has collapsed or the presence of pulmonary edema (abnormal collection of fluid in the lung).
During the program, certain donor organs previously classified as poor were subjected to specialized clinical maneuvers to improve lung quality. These procedures included bronchoscopic airway clearing of secretions, new mechanical ventilation strategies and use of diuretics to increase secretion of fluid.
As a result of these efforts, 135 organs were upgraded from poor to usable, making them eligible for transplantation.
"A key strategy for increasing the number of usable donor lungs in our study was modifying donor criteria by reassessing oxygenation, chest radiography and bronchoscopic findings as absolute criteria after active donor management," said Dr. Angel.
The authors concluded that implementing a similar donor-management program on a large scale at organ banks around the U.S., with a procurement rate approaching 25 percent, would nearly double the number of lung transplantation procedures, significantly decrease lengthy wait times and potentially eliminate many of the deaths that occur among patients awaiting lung transplantation.
In an editorial on the research in the same issue of the journal, Andrew C. Chang, M.D., of the University of Michigan Medical Center, and Jonathan B. Orens, M.D., of Johns Hopkins University School of Medicine, wrote: "It is intriguing that although organ offer rates increased to over 50 percent of consented donors, transplant centers in the organ procurement organization region accepted only 25 percent, indicating the potential for improving donor organ lung use even further than reported by this group."
"The study raises another important question regarding the availability of donor lungs. Are there truly not enough lungs? Although it has been thought that the available supply is far less than the demand, the supply may be less of a problem than actual use. Some countries outside the United States boast average use rates of 50 percent, with survival and functional outcome that compare favorably to the United States."
They concluded: "It is interesting to note that there has never been a large-scale prospective study to assess adequately the criteria used to identify the 'ideal donor.' As the demand for lung transplantation increases, such studies will be of great importance to understand better which organs are truly useable, and more importantly, which organs should be discarded. The study by Drs. Angel and colleagues underscores the importance of using an organized approach to donor management, coupled with the education of donor procurement organizations to improve donor organ use."