SAN FRANCISCO—A recent analysis of donor lungs rejected for use in transplantation has shown that many of them were potentially usable.[1] Currently, more than 85% of lungs are rejected. Although many patients die while waiting for donor lungs, the criteria used to assess suitability have not been prospectively evaluated, and few studies have examined the condition of rejected lungs.

To address this, Lorraine B. Ware, MD, and colleagues at the University of California, San Francisco, obtained 29 pairs of donor lungs that were rejected by the California Transplant Donor Network. The investigators’ criteria for lung suitability were as follows[1]:
• Absent or mild pulmonary edema.
• Normal alveolar fluid clearance.
• No significant microbial growth on culture.
• Normal or mildly abnormal histological findings.
• No nonpulmonary donor factors that would be cause for rejection.

“Published criteria include factors such as donor age, smoking history, chest radiograph findings, oxygenation, evidence of infection, and history of aspiration, trauma, or lung disease,” said Dr. Ware, now an Assistant Professor of Allergy, Pulmonary, and Critical Care Medicine at Vanderbilt University in Nashville, Tennessee. “Our criteria for deciding if a lung [was] suitable for transplantation were based on a laboratory evaluation of the lungs, not on a clinical evaluation of the donor.”

USABLE LUNGS IDENTIFIED

Using the study’s criteria, 12 of 29 pairs of rejected lungs were found to be usable for transplantation. Most had no or mild pulmonary edema, and all had measurable alveolar fluid clearance. An oxygen tension (PO2) of 300 mm Hg or more was associated with a lower mean water-to-dry-weight ratio and faster alveolar fluid clearance.

A normal chest film also correlated with faster alveolar clearance, but did not predict the degree of pulmonary edema. Although chest films are a standard part of the evaluation for lung transplant suitability, the researchers found they were not as useful as PO2 and could not be used to predict the presence of histologic abnormalities.

Histology revealed organisms in seven and neutrophils in 19 donor lungs. The presence of neutrophils was associated with bronchopneumonia. Tissue cultures were positive for bacteria in 13 lungs and Candida sp. in six. All cultures had a low colony count and many organisms were nonpathogenic.

According to Dr. Ware, the results were somewhat unexpected. “While we predicted that some lungs would appear suitable for transplantation, we did not think that this number would approach half of the lungs,” she admitted.

PRESENT CRITERIA NEED EVALUATING

Dr. Ware said that although published guidelines exist, many organ procurement organizations, centers, and individual surgeons modify the criteria somewhat. She noted that “the overall rate of donor lung utilization in the United States hovers around 15% and is not improving.”

If more usable lungs could be identified, the rate of donor utilization would more than double. “The criteria for selecting donor lungs need to be scientifically and prospectively evaluated in a multicenter trial to determine how [they] can be broadened without increasing risk to lung recipients,” Dr. Ware commented.

—Gale Jurasek

Reference
1. Ware LB, Wang Y, Fang X, et al. Assessment of lungs rejected for transplantation and implications for donor selection. Lancet. 2002;360:619-620.

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