Written by Vivian Lei
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Low dose ketamine (LDK) did not reduce overall pain or opioid use in this study of patients with rib fractures. However, for severely injured patients with ISS>15, ketamine allowed patients to achieve the same level of pain control with significantly less opioid medication.
Why does this matter?
Aggressive pain management is a core principle in treatment of rib fractures, and opioids continue as a front-line therapy. Low dose ketamine has been used as a supplementary method of analgesia and may be effective in reducing overall opioid use in trauma patients with rib fractures.
(Maybe) spare some opioids, infuse ketamine
In this RCT, 92 trauma patients with at least 3 rib fractures were randomized to either 48 hours of LDK infusion (2.5 mcg/kg/min based on ideal body weight) or placebo (0.9% NaCl). 75% of patients were male with a median age of 49 years and median injury severity score (ISS) of 14. Investigators looked at a primary endpoint of reduction in numeric pain scores (NPS) and secondary endpoints of opioid use in oral morphine equivalents (OME), hospital length of stay, epidural placement rate, respiratory complications, and other adverse events. While no difference was found in NPS or total OME at 12, 24, or 48 hours overall, a subgroup analysis showed that a significant reduction in OME was found in severely injured (ISS>15) patients receiving LDK. For this group, the total OME was 180.3 in the ketamine group vs. 328.5 in the placebo group, resulting in a mean OME savings of 148.2 over the course of a hospitalization. There were no significant differences between groups in hospital length of stay, rate of epidural placement, respiratory failure, or adverse events.
Source
Ketamine Infusion for Pain Control in Adult Patients with Multiple Rib Fractures: Results of a Randomized Control Trial. J Trauma Acute Care Surg. 2018 Oct 29. doi: 10.1097/TA.0000000000002103. [Epub ahead of print]
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Reviewed by Clay Smith
Its important to note the dose here was very low. They used a continuous infusion with no initial bolus. Their continuous infusion was very low dose (about 10 mg/hr for a 70 kg patient). It would be interesting to see the difference with an initial 10-20 mg bolus over 10 minutes followed by a low-dose infusion at a higher dose like 0.3 mg/kg/hr.