A recent study led by Southampton researcher and consultant nephrologist, Dr Kristin Veighey, has shown that ‘preconditioning’ kidneys before transplant, by temporarily cutting off the blood supply to the arm, can boost the long-term effectiveness of the transplanted kidney.
The simple procedure, using a standard blood pressure cuff, activates a natural protective reflex that limits the damage to a kidney that would usually occur as it is transplanted from a live donor to a patient.
Published in the British Journal of Anaesthesia, the study found patients’ kidneys worked better five years after the transplant if both they and their donor had the procedure, known as remote ischaemic preconditioning, just before surgery.
A simple method
Damage occurs to a kidney during transplant surgery, due to both the loss of its blood supply and attachment to new blood vessels in the receiving patient. Whilst reducing the transfer time can limit damage, the transplanted organ is still less effective than before.
Previous research has indicated that a natural protective reflex exists and, when activated, can help prevent damage to organs when the blood supply is stopped.
“Based on this prior knowledge we wanted to test a low-cost tool that, if proved successful, could easily be adopted across the NHS,” explained Dr Veighey.
“We decided on a standard blood pressure cuff that is easily accessible.”
In total 406 donor-recipient pairs took part across 15 European transplant centres. Both donors and patients had the same procedure, either 24 hours or immediately before their surgery.
Participants wore the cuff at the top of their arm, which was inflated to a tightness to temporarily cut off the blood supply (40mm Hg above their systolic blood pressure) for five minutes, and then deflated for five minutes. This was repeated three more times, to activate the reflex.
For comparison, one group of patients and their donors had a placebo procedure that didn’t cut off the blood supply to the arm and, therefore, didn’t activate the reflex.
As certain anaesthetics are thought to interfere with the reflex, the researchers conducted the whole procedure before any anaesthetics were given.
Transplanted kidneys have a limited lifespan – lasting on average 15 years – and it is normal to see a gradual decline in the kidney’s effectiveness.
The researchers found preconditioning immediately before surgery boosted the kidney’s effectiveness at the start, so even though this expected decline in function still occurred, these kidneys were still more effective five years later.
The researchers intend to go on to investigate the underlying mechanism, as well as determine whether just preconditioning either the donor or the patient has the same benefit.
“If this simple procedure could extend the lifespan of all transplanted kidneys, it has the potential to not only improve the lives of the patients receiving them, but also generate huge savings for the NHS by preventing the need for dialysis,” said Dr Veighey.
“While this procedure has seen mixed results in the past, we are investigating the possible reasons behind this – such as interference from anaesthetics – to enable this technique to realise its huge potential and deliver enormous benefits for patients with kidney transplants.”
Posted on Friday 15 November 2019