Normally, after retrieval, donor lungs are kept on ice less than eight hours. If too much time passes before the organ can be transplanted, the organ may become too damaged to be used. The maximum acceptable time in most centers has been six to eight hours.
Dr Cypel’s study reviewed 906 patients from 2006 to 2015 who received lung transplants at Toronto General Hospital. 97 of these patients received lungs which were preserved outside the body for more than 12 hours. The remaining patients received lungs that were preserved for less than 12. Despite the use of higher-risk organs, early outcomes between the two groups were similar.
“It’s a change in paradigm for how we do lung transplants,” said Dr. Cypel. “Now we don’t have to rush lung transplants; they don’t have to be emergency surgeries.”
With longer preservation times, organs can be retrieved from anywhere in North America. Longer preservation times allow for more flexibility in planning surgeries. Patients can travel to Toronto for their transplants rather than waiting in Toronto. The extra time can also be used to determine a better immunological match between donated lungs and recipients. Finally, it provides clinicians more opportunities to treat injured organs initially deemed unsuitable for transplant, he adds.
Dr. Shaf Keshavjee, in the Sprott Department of Surgery; James Wallace McCutcheon Chair in Surgery; Director of the Latner Thoracic Surgery Research Laboratories; and Director of the Toronto Lung Transplant Program 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.”
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. Donated 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 – first pioneered by Drs. Keshavjee and Cypel in 2008 at TGH. Subsequently lungs were subjected to protective cooling again until transplantation.
What is Ex Vivo Lung Perfusion?
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 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% 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.
For more information please watch this video explaining how EVLP system works.