Safety of 10°C Lung Preservation vs. Standard of Care: A Multi-Centre Prospective Non-Inferiority Trial

Despite lung transplantation (LTx) being the most effective treatment for end-stage lung disease, its success rate is lower than that of other solid organ transplantations. Primary graft dysfunction (PGD) is the most common post-operative complication and a major factor in early mortality and morbidity, affecting ~25% of lung transplant patients. Induced by ischemia reperfusion, PGD represents a severe and acute lung injury that occurs within the first 72 hours after transplantation, and has a significant impact on short- and long-term outcomes, and a significant increase in treatment costs. Any intervention that reduces the risk of PGD will lead to major improvements in short- and long-term transplant outcomes and health care systems.

One of the main strategies to reduce the risk and severity of post-transplant PGD is to improve pre-transplant donor lung preservation methods. In current practice, lung preservation is typically performed by cold flushing the organ with a specialized preservation solution, followed by subsequent hypothermic storage on ice (~4°C). This method continues to be used and applied across different organ systems due to its simplicity and low cost. Using this method for the preservation of donor lungs, the current maximum accepted preservation times have been limited to approximately 6-8h. While the goal of hypothermic storage is to sustain cellular viability during ischemic time through reduced cellular metabolism, lower organ temperature has also been shown to progressively favor mitochondrial dysfunction. Therefore, the ideal temperature for donor organ preservation remains to be defined and should maintain a balance between avoidance of mitochondrial dysfunction and prevention of cellular exhaustion. In addition to that, safe and longer preservation times can lead to multiple advantages such as moving overnight transplants to daytime, more flexibility to transplant logistics, more time for proper donor to recipient matching etc.

Building on pre-clinical research suggesting that 10°C may be the optimal lung storage temperature, a prospective, multi-center, non-randomized clinical trial was conducted at University Health Network, Medical University of Vienna and Puerta de Hierro Majadahonda University Hospital. Donor lungs meeting criteria for direct transplantation and with cross clamp times between 6:00pm - 4:00am were intentionally delayed to an earliest allowed start time of 6:00am and a maximum preservation time from donor cold flush to recipient anesthesia start time of 12 hours. Lungs were retrieved and transported in the usual fashion using a cooler with ice and transferred to a 10°C temperature-controlled cooler upon arrival to transplant hospital until implantation. The primary outcome of this study was incidence of Primary Graft Dysfunction (PGD) Grade 3 at 72h, with secondary endpoints including: recipient time on the ventilator, ICU Length of Stay (LOS), hospital LOS, 30-day survival and lung function at 1-year. Outcomes were compared to a contemporaneous conventionally transplanted recipient cohort using propensity score matching at a 1:2 ratio. 70 patients were included in the study arm. Post-transplant outcomes were comparable between the two groups for up to 1 year. Thus, intentional prolongation of donor lung preservation at 10°C was shown to be clinically safe and feasible.

In the current study design, the investigators will conduct a multi-centre, non-inferiority, randomized, controlled trial of 300 participants to compare donor lung preservation from the time of explant to implant at ~10°C in X°Port Lung Transport Device (Traferox Technologies Inc.) vs a standard ice cooler. When eligible donor lungs become available for a consented recipient, the lungs will be randomized to undergo a preservation protocol using either 10°C (X°Port Lung Transport Device, Traferox Technologies Inc.) or standard of care. The primary outcome of the study is incidence of ISHLT Primary Graft Dysfunction Grade 3 at 72 hours. Post-transplant outcomes will be followed for one year.