Cleveland Clinic researchers have published findings from two new studies examining the role blood transfusion and organ weight play in managing risk and mortality post-lung transplant, offering important insights to improve clinical care for patients who require lung transplant.
“Although more than 80 percent of lung transplant recipients survive for a year or more after their procedure, many can face severe complications,” said Kenneth McCurry, MD, a researcher in the Department of Inflammation & Immunity and senior author on both studies. “The goal of our research is to improve these outcomes for our patients by studying the risk factors that lead to post-transplant complications. By characterizing biomarkers indicative of complications, we can adjust our treatment plan to improve patients’ long-term prognosis.” Dr. McCurry is also a cardiothoracic surgeon in the Miller Heart, Vascular & Thoracic Institute, and part of the team celebrating two thousand lung transplants at Cleveland Clinic.
The effect of blood transfusion in donor lungs
As reported in their first study published in The Annals of Thoracic Surgery, Dr. McCurry and his team found that blood transfusion can cause detrimental effects on the pulmonary system and lead to higher morbidity and mortality in surgically- and critically ill-patients post-transplant.
Using data from 20,294 adult lung transplants gathered from March 1996 to June 2017 as part of the United Network for Organ Sharing, the researchers reviewed lung transplants from adult donors with known donor transfusion status. Recipient mortality was evaluated based on donor and recipient characteristics to assess whether recipient mortality risk modified the donor transfusion effect.
They found that transfusions of more than ten units of blood (a unit is roughly one pint, or 525 milliliters) was associated with increased 90-day mortality even among the lowest-risk recipients, while transfusion of less than ten units showed no increase in mortality even among the highest-risk recipients.
“This finding suggests that donor blood transfusion volumes should be considered when evaluating the fitness of donor lungs for transplant,” explained Dr. McCurry. “Based on these data, we believe that the lungs of potential donors who received transfusions of this magnitude may carry greater risk with transplantation, and that other donors should be prioritized depending on the severity of a recipient’s condition and situation. While unknown at present, it might be best to evaluate or treat lungs from high transfusion donors with ex vivo lung perfusion prior to transplantation.”
Changes in lung weight also affect transplant suitability
Ex vivo lung perfusion (EVLP) is an emerging technology that helps surgeons assess high-risk donor lungs and identify ways to repair them after removal from the donor and before transplantation into the organ recipient. One reason a lung may be considered for EVLP is pulmonary edema—sometimes called “wet lung”— a condition characterized by excess fluid accumulation in the lung sacs. Despite being a relatively common reason why donor lungs are considered unfit for transplant, there is currently no standard quantitative diagnostic tool to evaluate pulmonary edema in donor procurement.
In the team’s second study, recently published in Journal of Surgical Research, they found that three physiological indicators—lung weight at the donor hospital, lung weight at the end of EVLP, and lung weight change during EVLP—can be important predictors of transplant suitability in EVLP.
The researchers evaluated 21 rejected human lungs that underwent EVLP repair, looking for associations between organ weight, P/F value (the ratio of the partial pressure of oxygen in the lungs to the concentration of oxygen) and ultimate organ viability after EVLP.
They found that a lower donor lung weight at the donor hospital was associated with a high P/F ratio and greater transplant suitability two hours post-EVLP. They also discovered a significant difference in lung weight at the donor hospital between suitable cases and non-suitable cases, suggesting that initially rejected donor lungs may be recovered in EVLP if the organ is less than 1280 grams.
“Taken together, these findings suggest a significant correlation between lung weight and other physiological parameters in EVLP and points to the contribution lung weight plays in the decision-making process for transplant suitability,” said Dr. McCurry.
Dr. McCurry is first author of both studies, which were supported by Rosy and Ray Park. His research is also supported by the recently named Jack B. Lally Endowed Chair in Thoracic Surgery, which provides vital support for current and future endeavors related to thoracic surgery within the Heart, Vascular & Thoracic Institute at Cleveland Clinic.