St. Louis, MO—Based on evidence that administering ketamine could curb postoperative pain and lower the need for opioid painkillers postsurgery, the drug often is used in small quantities during surgical procedures.

More recent research even suggests that ketamine holds promise for easing postsurgical delirium in older patients.

A new study published in The Lancet reports, however, that the benefits are not as great as hoped and that the downsides are also significant.

Led by Washington University School of Medicine in St. Louis researchers, the study determined that ketamine doesn’t lower levels of pain or reduce the need for pain-killing opioid drugs after surgery.

Furthermore, according to the study, older patients who received ketamine during surgery are at increased risk for hallucinations and nightmares in the recovery room and for several days following their procedure.

“In recent years, there’s been a big increase in the amount of ketamine given in the operating room because clinicians are trying to prevent pain after surgery without relying on opioid drugs,” explained first author Michael S. Avidan, MBBCh, a professor of anesthesiology and of surgery at Washington University. “We found that the current practice of giving low doses of ketamine to patients during surgery is not having the desired effect. So we need to determine whether higher doses might be more effective, or we need to find other alternatives to opioids.”

For the study, 672 surgery patients, at least 60 years old, were tracked in the United States, Canada, India, and South Korea. During surgery, the patients received either no ketamine, a very low dose of the drug, or a slightly higher dose. The doses of ketamine were in line with the amounts administered by anesthesiologists seeking to lower patients’ levels of postoperative pain.

After surgery, the patients were questioned about their pain, while researchers kept track of the amount of opioids needed to control the pain and evaluated the patients twice daily for delirium, which can include confusion, agitation, and an inability to recognize friends and family members.

“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,” Avidan added. “Overall, patients who develop delirium have worse outcomes and are at higher risk for long-term cognitive decline. So it's really important to try to prevent it if we can.”

He suggested the common practice of giving low doses of ketamine during surgery be reconsidered, adding, “Our study didn’t indicate that it was effective.”

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