Intraoperative Ketamine: Further Research Needed for Analgesic Use

A recent study has failed to confirm the conclusions of smaller, earlier research suggesting the effectiveness of ketamine in reducing postoperative delirium and pain. Senior author George Mashour, MD, PhD, professor of anesthesiology and associate dean for clinical and translational research at the University of Michigan Medical School, commented, “Previous studies found evidence that ketamine could prevent delirium and reduce pain after surgery. However, these studies were often in small cohorts. We felt it was beneficial to test the effects of ketamine on delirium and pain in a multicenter, international study of older patients at risk who were undergoing major surgery.” The new findings are published this week in The Lancet.

Lead author Michael Avidan, MBBCh, professor of anesthesiology and cardiothoracic surgery at Washington University School of Medicine in St. Louis, observed that postsurgical pain and delirium are often linked, and that “When patients become delirious after surgery, they tend to spend more time in the intensive care unit, have longer hospital stays and have a greater chance of dying. It’s really important to try to prevent it if we can.” To test ketamine, as an opioid-sparing alternative for pain, the team assessed 1360 patients aged 60 or older who underwent major surgery between 2014 and 2016. 672 patients were selected for blinded randomization into 3 groups—placebo, low-dose ketamine and high-dose ketamine. At 3 days postsurgery, no differences were found between the 3 groups in either delirium incidence, pain scores, or median opioid consumption. Of the findings, which contradicted earlier conclusions, Dr, Mashour said, “It’s a noteworthy study in terms of current practice. The administration of ketamine during surgery is becoming widespread. We recommend further research on the drug to ensure we are not administering something that isn’t working to benefit our patients.”

Read a news story about the findings.

The journal abstract may be read here.

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• opioid sparing