Dr. Jacques Malaise, from Centre Hospitalier de l'Université de Montréal, Université de Montréal, Canada, shares his experience of using machine perfusion not just in deceased donors but also for living donors.
Please share with us some information about your center
We are one of six transplant centers in Québec province. At our center we do about 70–80 deceased and living donor kidney transplants each year and between 15–20 living donor transplants. Like many other centers our donors have become more marginal over the years, accounting for 25% of our donor pool today. Even some of our younger donors are what we might call ‘marginal’ given the cause of death is more likely to be anoxia or cerebral vascular injury than a road traffic accident.
What was your rationale for pumping all your deceased donor kidneys?
Before arriving in Montréal, I had experience pumping in Belgium and had seen the benefits not just in marginal donor organs but in young donors. We know that we lose kidneys that have had delayed graft function (DGF) at 7 or 8 years post-transplantation and these patients end up back on dialysis and the re-transplant waiting list. Our practice now is to pump all our donor kidneys even though our cold ischemic times are quite short. We believe any time on the pump is better for the long-term function of the kidney and may help to reduce the number of re-transplantations in the future. In our practice today, we see DGF rates of between 10–12% and we know that most of our patients are able to go home usually within 11 days. In our most recent experience we see 99% patient survival and 95% graft survival at one year.
What challenges and opportunities have you faced in your approach?
From a practical point of view, at our center there is also a lung transplantation programme and we often find we have to wait in line for access to the anesthesiologists and nurses so the pump can play an important role in these cases. Some of my colleagues have needed some convincing to pump all kidneys, both from an efficacy and logistical point of view. Seeing immediate early function following successful reduction in renal resistance on the pump helped colleagues understand the value of the machine. For others it took some time to get used to the idea that the pump can be left on its own and travel unattended.
You have been the first to report using machine perfusion in living donors. Please tell us more?
We often see in our living donor recipients that kidney function may not be as good as we might expect immediately post-transplantation with creatinine levels taking time to drop. We wanted to evaluate the resistance in living donor kidneys. To our surprise we found more than 50% with a renal resistance level, that had we seen it in a deceased donor, we may not have transplanted the kidney! Following even a short time on the pump (2 hours 24 minutes ± 36 minutes) we saw the renal resistance fall from 0.96 ± 0.58 mmHg/ml/min to 0.29 ± 0.12 mmHg/ml/min. We had good early function, with creatinine falling faster than historical controls and the patient out of hospital at least a day earlier than we would have expected in the past.
So what are your next plans for machine perfusion?
Two main avenues, first the use of the machine for the paired exchange program and allow the kidney to travel instead of the donor. This is particularly important in the US, where some kidneys travelling in their program have a long cold ischemic time of more than 18 hours. Second, the use of drugs during perfusion, knowing that at low temperature, most of the drugs are not potent with a very slow metabolism.