Conference Coverage

Low-dose ketamine controls pain from severe chest injury, while sparing opioid consumption



For patients with severe rib injuries, low-dose ketamine infusions kept pain under control while reducing opioid consumption.

Dr. Nathan Kugler Michele G Sullivan/MDedge News

Dr. Nathan Kugler

The anesthetic didn’t make much difference in pain control or opioid use overall in a randomized study of 93 patients with thoracic injury Nathan Kugler, MD, said at the annual meeting of the American Association for the Surgery of Trauma. But among severely injured patients, it cut the opioid mean equivalency dose by about 164 mg over the 48-hour infusion and by 328 mg over a mean hospital stay while maintaining pain control, said Dr. Kugler, a surgical resident at the Medical College of Wisconsin, Milwaukee.

“With increasing focus on multimodal pain strategies, opioid-based regimens continue to be the backbone of pain control,” he said. “We have used ketamine effectively for failure of maximum therapy and demonstrated an opioid-sparing effect.” This new research shows that the drug can be an effective adjunct for acute pain control for severely injured patients in the emergency setting.

The study recruited 93 patients with thoracic injury; they had a mean of six broken ribs, mostly caused by motor vehicle accidents. Most of the patients were male (75%), and their mean age was 46 years. The mean Injury Severity Score was about 15; about 30% had flail chest.

All patients received a standardized acute pain medication regime comprising acetaminophen, nonsteroidal anti-inflammatories, methocarbamol (Robaxin), and intravenous opioids. Regional therapies included rib block with an epidural catheter. In addition, they were randomized to placebo infusions or to 48 hours of IV ketamine at 2.5 mcg/kg per minute. “To put this in perspective, for a 70-kg patient, that is a mean of 10.5 mg/hour,” Dr. Kugler said.

The primary endpoint was a reduction of at least 2 points on an 11-point pain scale. Secondary endpoints included opioid use in oral morphine equivalents (OME); respiratory complications; and psychoactive events. The primary outcome was assessed with an area under the curve model.

In the overall group, there was no significant between-group difference in pain score. Nor were there differences in the total OME at 12-24 hours (184 mg ketamine vs. 230 mg placebo), or at 48 hours (86 vs. 113 mg).

Dr. Kugler also looked at these outcomes in patients who had only rib fractures independent of other chest injury. He saw no significant differences in pain scores or OME at 24 or 48 hours.

However, significant differences did emerge in the group of severely injured patients with an Injury Severity Score of more than 15. There were no differences in pain scores at either time point. However, ketamine allowed patients to achieve the same level of pain control with significantly less opioid medication. The OME at 12-24 hours was 50.5 mg vs 94 mg. At 24-48 hours, it was 87 mg vs. 64 mg.

This worked out to a mean OME savings of 148 mg over a patient’s entire hospitalization.

“We saw a very nice separation of opioid consumption that began early and continued to separate over the 48-hour infusion and even after it was discontinued,” Dr. Kugler said.

This benefit was achieved without any additional adverse events, he added. There were no significant differences in confusion; epidural placement; length of stay; respiratory event, sedation, hallucinations, delusions or disturbing dreams; or unplanned transfers to the ICU.

Dr. Kugler disclosed that he and primary investigator Thomas Carver, MD, also of the Medical College of Wisconsin, Milwaukee, are both paid consultants for InnoVital Systems.

SOURCE: Carver T et al. AAST 2018, Oral abstract 2

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