In what will prove to be a huge boon for lung transplant recipients, a new breakthrough enables donor lungs to be preserved for up to 20 hours – more than double the time – outside the body.
The work, published in The Lancet Respiratory Medicine, is the result of the work carried out by Dr. Marcelo Cypel and colleagues wherein they demonstrated that instead of just 6-8 hours donor lungs can be preserved for up to 20 hours with the help of ex vivo lung perfusion thereby paving way for more transplants to be performed with greater flexibility in their timing.
Researchers say that their study is all set to change the lung transplant paradigm and will benefit hundreds of thousands of people around the year who are required to live near transplant centres away from their homes and loved ones waiting for donor lungs.
Researchers reviewed 906 patients from 2006 to 2015 who received lung transplants at Toronto General Hospital. Ninety-seven (97) of these patients received lungs which were preserved outside the body for more than 12 hours, with an average of 14.6 hours, while 809 patients received lungs that were preserved for less than 12 hours – on average about 6.7 hours. Despite the use of higher-risk organs in the group in which lungs were preserved for more than 12 hours, early outcomes between the two groups were similar.
The team then followed up with the two groups for two and a half and four years, and the main results measured were primary graft dysfunction, or injury to the lung after the first 72 hours and a leading cause of death after transplantation, intensive care unit and hospital stay and survival of patients. No differences were observed between the two groups in primary graft dysfunction, and length of hospital and intensive care unit stay was the same between the two groups.
At one year, the survival of patients who received lungs preserved less than 12 hours was 86 per cent, and 87 per cent for those who received lungs preserved for more than 12 hours. The widely accepted International Society of Heart and Lung Transplantation benchmark for one-year survival of lung transplant patients is 80 per cent.
The study used a combination of warm and cold preservation to increase the length of time the lungs were able to survive safely outside the donor body.
Retrieved lungs were first cooled to slow down deterioration and tissue injury, transported to TGH, then treated and evaluated with the ex vivo lung perfusion (EVLP) system for four to six hours. Subsequently lungs were subjected to protective cooling again until transplantation. In the EVLP system, the lungs are placed in a protective dome in which a system continuously pumps a bloodless solution of oxygen, proteins and nutrients into the injured donor lungs, mimicking normal physiological conditions. This makes it possible for the injured cells to begin repairing themselves, and sets the stage for more sophisticated repair techniques to be applied to donor lungs.
Since 2012, there has been an unprecedented 30 per cent increase in lung transplants at TGH as a result of the EVLP system. TGH now routinely performs more than 120 lung transplants a year, making this one of the largest centres in the world.
“Now we don’t have to rush. Lung transplants don’t have to be emergency surgeries”, says Dr. Cypel.
Dr. Shaf Keshavjee, Director of the Toronto Lung Transplant Program, Surgeon in Chief, Sprott Department of Surgery at UHN, says that “instead of racing the clock to transfer the organ from the donor to the recipient, we have created the opportunity for more detailed assessment and treatment of the organ, while also providing valuable hours to optimize the logistics of the transplant operation. This will eventually translate into improved outcomes and reduced costs of organ transplantation.”