Kidney damage clues revealed

More than 750,000 people worldwide undergo bypass operations each year

Scientists in the US believe they may have discovered why one in 12 people who undergo coronary artery bypass surgery suffer serious kidney damage.

The study, carried out at the Duke Medical Center in New Orleans, could pave the way for targeted medication to protect the kidneys during surgery.

Kidney damage during heart surgery is thought to be caused when toxins, which reside in the gut, are released into the blood stream and cause inflammation of the kidneys.

The researchers believe the toxins, called endotoxins, are released in response to the use of the heart-lung machine - used to pump blood through the body during a heart bypass operation.

As a result of the inflammation the kidneys' ability to filter blood effectively is impeded.

But patients with higher levels of antibodies to neutralise the toxins are less likely to suffer kidney damage, the study found.

Interventions

Dr Mark Stafford-Smith, who led the study, released his findings at the annual scientific session of the American Society of Anesthesiologists.

He said: "We found that patients who had higher levels of antibodies circulating in their blood to neutralise or soak up these toxins had much better kidney function after surgery.

"We can now come up with an intervention that either dampens the release of these toxins or increases the production of the antibodies, or both."

More than 750,000 people worldwide undergo bypass surgery every and it is believed up to 8% will suffer kidney damage as a direct result of the procedure.

While most cases of kidney damage are short-lived up to 2% of patients will require dialysis.

More than half of those requiring dialysis will die before being discharged from hospital.