Ketamine Fails to Prevent Chronic Pain in Trauma Patients

Author: Nikki Kean

Anesthesiology News

To help prevent the development of chronic pain after acute trauma, clinicians have begun to study the use of continuous ketamine infusion in the ICU. However, preliminary data presented at the 2018 ACCP Global Conference on Clinical Pharmacy indicated problems with such a strategy.

In a small retrospective study, Cara Coleman, PharmD, of the University of Cincinnati James L. Winkle College of Pharmacy, in Ohio, and her colleagues found no benefit from continuous ketamine infusion (6.0 mg/kg per minute) for prevention of chronic pain at three months (poster 13).

The stakes are high for controlling pain in trauma patients, Coleman said. For such patients, “the development of chronic pain is a significant challenge,” she said. Moreover, “these patients may develop a tolerance to traditional pain medications, such as opioids and neuropathic pain agents, requiring repeated modifications that carry an increased risk of side effects.”

She and her colleagues conducted a retrospective review of opioid requirements at admission, discharge and one and three months after discharge in patients who received continuous infusion of ketamine between January 2016 and October 2017. The researchers compared a ketamine group with a control group that received traditional postoperative pain management.

Despite the significant reduction in opioid requirements, the number of patients with chronic pain at three months was similar between groups: 19 patients in the ketamine group and 15 patients in the control group.

Although the primary outcome did not show an advantage with ketamine infusion for prevention of chronic pain, two baseline characteristics differed between the groups: body weight and, as noted, opioid requirement at admission. Coleman noted, “Obese patients seemed to do better with the ketamine infusion.”

The researchers also noted that the nine patients who started their ketamine infusion after 72 hours from admission had a lower opioid requirement at three months than the 18 patients who began the infusion within 72 hours (20 vs. 105 mg/kg). “One hypothesis for this occurrence is that these [delayed-therapy] patients may have had a lower threshold for opioid toxicities and therefore also discontinued therapy sooner,” Coleman said. “The median doses in the patients receiving ketamine later were 50% to 70% of those receiving ketamine earlier, which is consistent with a lower tolerability in this group.”