Avoiding Primary Graft Dysfunction After Lung Transplant
Lung transplantation can be a life-saving procedure—one that has become especially important during the COVID-19 pandemic. But it carries a risk of complications, chief among them primary graft dysfunction (PGD). This syndrome is characterized by pulmonary edema (fluid in the air sacs of the lungs) that makes it harder for patients to breathe. For this reason, severe PGD can be deadly to a patient with a new lung.
Some evidence suggests that PGD is associated with the use of two forms of extracorporeal life support used during lung-transplant operations.
Cardiopulmonary bypass (CBP) is used to oxygenate and circulate patients’ blood during the transplant procedure. Extracorporeal membrane oxygenation (ECMO) provides the same kind of support to a lesser degree, but it is also less invasive than CPB. Some patients are judged not to require either CPB or ECMO and are instead supported “off-pump” with ventilation of their single, native lung during the procedure.
To examine the relationship between extracorporeal life support and PGD, Gabriel Loor, MD, a member of the teaching staff with Texas Heart Institute and Baylor College of Medicine’s joint Cardiothoracic Transplantation and Circulatory Support program and Surgical Director of Lung Transplantation at Baylor-St. Luke’s Medical Center, worked with colleagues at 10 high-volume lung-transplantation centers in the United States and Europe that contribute to the Extracorporeal Life Support in Lung Transplantation Registry.
Using data from 852 lung transplantation operations performed between January 2016 and March 2020, the investigators compared the rate of grade 3 PGD (PGD3, the most severe form of PGD) among patients who underwent lung transplantation with CPB (including cases in which both CPB and ECMO were used), with ECMO alone, or off-pump.
The analysis revealed that patients who underwent off-pump operations had the lowest rate of PGD3 (12.1%), patients with ECMO had a moderate rate (28.9%), and patients with CPB had the highest rate (42.7%). This was not surprising, as patients who need more intraoperative support tend to be those with more severe illness and other risk factors. But even when statistical techniques such as logistic regression and propensity matching were used to account for the effects of these risk factors, patients’ risk of PGD3 was still highest with CPB and lowest with off-pump surgery, suggesting that extracorporeal life support—especially CPB—is itself a risk factor for PDG3.
“Perfusion devices to support the heart and lung in patients undergoing lung transplant are critical to the safe conduct of the operation in many cases,” says Dr. Loor. “The current study suggests that ECMO is the preferred strategy for supporting patients during lung transplant when the procedure cannot be safely done off-pump.”
Loor G, Huddleston S, Hartwig M, et al. Effect of mode of intraoperative support on primary graft dysfunction after lung transplant. J Thorac Cardiovasc Surg. 2022; doi: https://doi.org/10.1016/j.jtcvs.2021.10.076.
News Story By Stephen N. Palmer, PhD, ELS