Bucking conventional wisdom, a new study shows that lung transplant patients may live longer if they receive oversized donor lungs.
“Size is a more powerful predictor of survival than we ever thought,” study author Ashish Shah, MD, said in a statement. “Fears of [transplanting] oversized lungs appear to be unfounded.”
Researchers at Johns Hopkins University School of Medicine in Baltimore arrived at their conclusion after analyzing data from 4520 double lung transplants and 2477 single lung transplants performed in adults in the United Network for Organ Sharing lung transplant registry between May 2005 and April 2010.
The investigators calculated the ratio of the donor’s predicted lung capacity relative to that of the recipient. A ratio of 1.0 would be considered a perfect match. But a ratio of 1.3 would indicate that the donor lung is oversized because it’s substantially larger than the recipient’s total lung capacity.
Among patients who had double lung transplants, each 0.1 increase in the predicted lung capacity ratio translated into a 7% decreased risk of dying within a year of having the surgery; a ratio of 1.3 would confer nearly a 30% reduced risk of dying in the first year after transplantation. The association remained significant when the investigators accounted for patients’ diagnoses, other illnesses they had, the amount of nursing care they required, and donor characteristics. Oversized lungs in single lung transplants conveyed a smaller survival benefit, but the association was stronger in double lung transplants.
Donor lung size garnered national attention in June when a 10-year-old Pennsylvania girl with severe lung damage from cystic fibrosis needed a lung transplant. Sarah Murnaghan was denied adult donor lungs because of an age restriction.
Children younger than 12 years aren’t eligible to receive adult lungs, primarily because of the size mismatch. After Murnaghan’s parents successfully challenged the policy in a lawsuit, she had 2 double lung transplants, the second after the first pair failed. She currently is recovering at Children’s Hospital of Philadelphia.
Shah, who is surgical director of lung transplantation at the Johns Hopkins Hospital, said the study, published today in the Annals of Thoracic Surgery, indicates each patient’s lung capacity is a more important determinant than age or height in matching recipients with donor lungs. Children can have good outcomes with adult lungs and some small adults could do well with pediatric lungs, he explained.
“We hope this research dispels some myths,” he said.