Give our friendly team a call [07] 3180 1840

​Reducing post-surgical pain

Tuesday 20 July 2021

Around 10 to 15 per cent of patients who have major surgery will go on to experience chronic and persistent post-surgical pain (CPSP), a debilitating complication for patients that currently costs the Australian economy billions of dollars a year.

The Reduction Of Chronic post-surgical pain with Ketamine (ROCKet) Trial led by Professor Philip Peyton at the University of Melbourne and supported by the Australian and New Zealand College of Anaesthesia (ANZCA) Clinical Trials Network (CTN) is a large randomised controlled trial looking at whether the use of ketamine as a pain relief option after surgery may decrease the risk of developing surgery related chronic pain. The study is led locally by Principle Investigator, Dr Jo Rotherham, the Director of the Acute Pain Service at the PA Hospital.

The PA Hospital is one of the leading recruitment sites for the ROCKet Trial and has recently celebrated a trial milestone by reaching over 150 enrolled patients. Associate Professor Pal Sivalingam, Director of Research for the Anaesthetic Department, said the study hopes to confirm findings from smaller studies which have shown ketamine to be effective in chronic and persistent pain after major surgery.

Dr David Highton, A/Prof Pal Sivalingam and Allison Kearney

"All painkillers work in different pathways, ketamine is an NMDA receptor antagonist," A/Prof Sivalingam said.

"NMDA receptors in the spinal column deliver pain signals to the brain. Ketamine blocks these receptors and stops pain signals travelling to the brain, that is why it has been chosen. Ketamine is a fully approved medication currently used for the treatment of acute pain. Initial studies have shown promising indications that ketamine may also reduce chronic post-surgical pain."

Patients in the blinded multi-centre study are given a trial infusion through their drip for up to three days and followed up by trial team members on each day they are in hospital, then at three months and twelve months once they're discharged. As this is a randomised controlled trial, enrolled patients are allocated a 50% chance of either receiving the medication or a placebo (saline).

Trial participants are closely monitored for any side effects which can include strange dreams and hallucinations due to the action of ketamine on nerves and the brain. The trial infusion can then be increase, decreased or stopped altogether depending on the level of side effects and patient pain.

"This is part and parcel of using ketamine. Sometimes the dreams are pleasant, sometimes they are not pleasant. About 10 percent of patients will report a side effect of some description, but many do not need to cease their infusion as the side effects are mild. The trial has been built in such a way that you can reduce the dose as needed, as patient safety always comes first," A/Prof Sivalingam said.

"At the same time, this is not the only pain relief patients have. All of the other usual pain relief options including epidural, spinal, PCA (Patient Controlled Analgesia), all other pain relief drugs including other opioids will be offered or are being given anyway. Patients are in no way being adversely affected by pain because of the taking part in the trial. The goal is for the trial infusion to only ever be an additional form of pain relief."

The ROCKet trial's importance from a public perspective is the study has the potential, if successful, to reduce the percentage of patients with chronic post-surgical pain, and potentially not only help the patients and their families but help the wider Australian economy by reducing the need for patients to visit doctors or take medicine to reduce their persistent chronic post-surgical pain.

"When a patient's in pain, it is not only taxpayer's money that is used to treat their pain, they have to get leave and they're not going to work," A/Prof Sivalingam said.

"Apart from that, people who are in pain can get dependent on opioids, and then they can become addicted which causes all sorts of problems in their lives. "The pain, economy, patients avoiding drug dependence. There's a lot of potential benefits in this trial."

A/Prof Sivalingam said the PA Research Foundation had been a consistent supporter of anaesthetic research and advancement at the PAH, funding Clinical Coordinators and helping stage an annual anaesthetics conference.

"As clinicians we have a full clinical workload, and we have to carry our research work as well. We don't mind doing that at all and putting in extra effort, but we cannot just leave the clinical work side, so to have a research team is incredibly helpful to us," he said.

Donate to support key anaesthetic research at the PA Hospital here.