RCT: Low-Dose Ketamine Enhances Pain Relief When Added to Morphine in ED Patients
20 Nov, 2024 | 14:42h | UTCBackground: Acute pain is a prevalent complaint among emergency department (ED) patients, yet effective pain management remains suboptimal, especially in individuals with current opioid use due to opioid tolerance and hyperalgesia. Low-dose ketamine (LDK) has been proposed as an adjunct to opioids to enhance analgesia through synergistic or additive effects, but its efficacy in patients with and without current opioid use in the ED setting is not well established.
Objective: This randomized controlled trial aimed to determine the effectiveness of LDK as an adjunct to morphine versus morphine alone for acute pain management in ED patients with and without current opioid use.
Methods: In this single-center, double-blind study, 116 adult patients presenting to the ED with acute pain (numeric rating scale [NRS] ≥5) requiring intravenous opioids were randomized to receive either 0.1 mg/kg ketamine or isotonic saline (placebo) as an adjunct to morphine. Patients with and without current opioid use were randomized separately. Pain intensity was measured at baseline and at 10, 20, 30, 45, 60, and 120 minutes post-randomization. The primary outcome was pain reduction from baseline to 10 minutes. Secondary outcomes included pain intensity over 120 minutes, need for rescue opioids, side effects, and patient and provider satisfaction.
Results: The study included 116 patients (median age 51 years; 58% male; 36% with current opioid use). Pain reduction from baseline to 10 minutes was significantly greater in the LDK group compared to placebo (median reduction of 4 [IQR 3–6] vs. 1 [IQR 0–2]; p = 0.001). Pain intensity was significantly lower in the LDK group at 10, 20, and 30 minutes post-administration. There was a higher incidence of nausea, vomiting, and dissociation in the LDK group during the first 10 minutes. No significant differences were observed in the need for rescue opioids or in patient and provider satisfaction between groups.
Conclusions: LDK administered as an adjunct to morphine significantly enhances short-term pain relief in ED patients with acute pain, regardless of current opioid use status. However, the increased risk of transient side effects necessitates careful consideration.
Implications for Practice: LDK may be considered as an adjunct to morphine for acute pain management in the ED, particularly when traditional opioid treatments are insufficient. Clinicians should weigh the benefits against the potential for transient side effects, and LDK should not be universally recommended for all patients with moderate to severe pain.
Study Strengths and Limitations: Strengths of the study include its randomized, double-blind design and the inclusion of patients with current opioid use. Limitations include early termination leading to a smaller sample size, potentially underpowering the stratified analysis, and heterogeneity in patient pain conditions. Additionally, assessing the primary outcome at 10 minutes may not capture the peak effect of morphine.
Future Research: Further studies should focus on optimizing LDK administration protocols, such as exploring bolus versus continuous infusion methods, to achieve sustained pain reduction and minimize side effects.