A new Australian led study will investigate whether the perioperative use of ketamine could be a solution to the invisible but significant problem of chronic pain following thoracic, abdominal, orthopedic and other surgery.

The randomised controlled trial of ketamine versus placebo will commence recruitment this year following an award of $4.8 million in NHMRC funding.

Associate Professor Philip Peyton, from the Anaesthesia, Perioperative and Pain Medicine Unit at the University of Melbourne, said they would aim to recruit 5,000 participants across Australia, New Zealand and Hong Kong.

“The NHMRC review panel clearly recognises the magnitude and importance of this long-term pain problem.”

“Evidence from some small trials is encouraging but we need the big, multicentre study to demonstrate the treatment effect on a large scale.”

Associate Professor Peyton said about one in eight people had significant ongoing pain after surgery, the costs were substantial and public waiting lists for pain management were huge.

“Tens of thousands of Australians are affected given we perform about 250,000 operations each year,” he told the limbic.

A 2007 Access Economics report found chronic pain cost the community about $34 billion per year including health system costs and productivity losses.

“Many physicians will be surprised at how common chronic postsurgical pain is. It is a ‘sleeper issue’ because patients leave hospital, their surgeons might review them at six weeks but then patients often just need to manage as best they can.”

“The pathophysiology of chronic pain is complicated but we know it is more likely when there is the nerve damage, for example, to the intercostal nerves during thoracic surgery.”

Wound complications such as infection, pre-existing pain, and psychological factors such as anxiety can all increase the risk, Associate Professor Peyton said.

He said ketamine potentiates the effect of opioids, which were the mainstay of acute pain management.

“We’re looking for that sweet spot – a low dose of ketamine as part of a multimodal approach targeting receptors involved in pain without side effects such as its known hallucinogenic properties.”

The study protocol would include an IV loading dose of ketamine given with the anaesthetic pre-incision and continuous infusion during surgery and post operatively for up to three days.

The study aims to show a 25% reduction in the number of people with pain at the 12-month follow-up.