Forty per cent of heart-bypass patients may suffer continued cognitive decline as a result of the surgery over a period of five years, writes Natasha Gilbert.
Now, a collaboration of UK and US scientists has found that a rare element of air could prevent this.
Mervyn Maze of the department of anaesthetics and biological sciences at Imperial College London and Hilary Grocott of the department of anaesthesiology at Duke University Medical Centre, US, along with their teams, conducted heart-bypass surgery on rats and found that xenon prevented reduced brain function resulting from nerve damage.
The researchers think this protective effect could prevent damage to the human brain caused by heart-lung machines used during bypass surgery. The mechanically pumped blood lacks a pulse, and this can disrupt nerve cells, leading to impaired brain function. "We are optimistic that xenon will prevent predictable injury," Professor Grocott said.
The team first highlighted xenon's ability to guard against nerve damage during an in vitro experiment, reported by The THES last year. While the scientists anticipated a similar result in the present study, published in The Journal of Anesthesiology , "xenon's efficacy and long-lasting protective effect is much greater than expected", Professor Maze said.
Used as an anaesthetic for more than 50 years, xenon is an extremely safe drug. However, the atmosphere contains just 0.00009 per cent of the gas, which is consequently very expensive. To ensure xenon's wider use, the researchers teamed up with Air Products, a US gas company, to develop a way of recycling the gas. Because the body does not alter the structure or composition of xenon, it can be reused.
Human trials of xenon have begun in the UK with plans to extend these in the US later this year. According to Professor Grocott, the sooner the better. Currently, there are no neuroprotective agents approved for use during bypass surgery. A positive result "could have a profound impact on the quality and quantity of patients' lives and save on long-term health costs".