Low dose ketamine (LDK) has been proved to be an ideal analgesic because of profound pain relief, potentiation of opioids, role in preventing opioid hyperalgesia, and the large margin of safety associated with its use. This clinical trial deduced that LDK use leads to a significant reduction in oral morphine equivalent utilization during the first 24-hours in severely injured patients. 

Rib fractures occur in about 40% of trauma patients and are concerned with increased mortality. Opiate-based pain regimens remain the cornerstone of rib fracture management; however, concerns regarding opioids have fostered an interest in alternative analgesics. Ketamine is currently being used instead of opioids, but little evidence exists supporting its use within the trauma population.

A prospective, randomized, double-blind placebo-controlled trial of adult patients with ≥three rib fractures admitted to a Level 1 trauma centre was performed. Exclusion criteria comprised of age >64 years, GCS <13, and chronic opiate use. The experimental arm obtained low dose ketamine (LDK) at 2.5 mcg/kg/min, whereas the placebo cohort obtained an equivalent rate of 0.9% normal saline for 48 hours. The primary outcome was the reduction in numeric pain score (NPS) during the first 24 hours. Secondary outcomes studied comprised of oral morphine equivalent (OME) utilization, length of stay, epidural rates, pulmonary complications, and adverse events.

Forty-five of 91 patients (49%) were randomized to the experimental arm. Both groups were similar in makeup. Overall, 74.7% were male, had a median age of 49 years, and an injury severity score (ISS) of 14. LDK was not associated with a significant reduction in 24-hour NPS or OME totals. Subgroup analysis of 45 severely injured patients (ISS >15) demonstrated that LDK was associated with a considerable decrease in OME utilization during the first 24-hours (35.7 vs 68, p=0.03), 24-48 hours (64.2 vs 96, p=0.03), and overall (152.1 vs 198, p=0.048). No difference in other secondary outcomes or adverse events was noted.

LDK failed to decrease NPS or OME within the overall cohort, although there was a decrease in OME observed among patients with an ISS >15. Confirmatory studies are required to determine if LDK is a useful adjunct among severely injured patients.