A Prospective Randomized, Double-dummy Trial Comparing IV Push Low Dose Ketamine to Short Infusion of Low Dose Ketamine for Treatment of pain in the ED

Study Objective: Compare adverse effects and analgesic efficacy of low-dose ketamine for acute pain in the ED administered either by single intravenous push (IVP) or short infusion (SI).

Methods: Patients 18-65, presenting to ED with acute abdominal, flank, or musculoskeletal pain with initial pain score≥5, were randomized to ketamine 0.3mg/kg by either IVP or SI with placebo double-dummy. Adverse effects were evaluated by Side Effects Rating Scale for Dissociative Anesthetics (SERSDA) and Richmond Agitation-Sedation Scale (RASS) at 5, 15, 30, 60, 90, and 120min post-administration; analgesic efficacy was evaluated by Numerical Rating Scale (NRS).

Results: 48 patients enrolled in the study. IVP group had higher overall rates of feeling of unreality on SERSDA scale: 92% versus 54% (difference 37.5%; p=0.008; 95% CI 9.3-59.5%). At 5min median severity of feeling of unreality was 3.0 for IVP versus 0.0 for SI (p=0.001). IVP also showed greater rates of sedation on RASS scale at 5min: median RASS -2.0 versus 0.0 (p=0.01). Decrease in mean pain scores from baseline to 15min was similar across groups: 5.2±3.53 (95% CI 3.7-6.7) for IVP; 5.75±3.48 (95% CI 4.3-7.2) for SI. There were no statistically significant differences with respect to changes in vital signs and need for rescue medication.

Conclusion: Low-dose ketamine given as a short infusion is associated with significantly lower rates of feeling of unreality and sedation with no difference in analgesic efficacy in comparison to intravenous push.