Intravenous Lidocaine Provides Similar Analgesia to Intravenous Morphine for Undifferentiated Severe Pain in the Emergency Department: A Pilot, Unblinded Randomized Controlled Trial.

Abstract

We compared the analgesic effects of intravenous (IV) lidocaine and IV morphine for the treatment of severe pain in the emergency department (ED). This was a pilot, unblinded randomized controlled study comparing the efficacy of IV lidocaine vs IV morphine for patients aged ≥18 years with severe pain (numerical rating scale [NRS] ≥ 7). Participants were randomized to receive IV lidocaine (75 mg if <50 kg, 100 mg if 50-100 kg, and 150 mg if >100 kg) over 10 minutes, followed by a 50-minute IV lidocaine infusion of the same dose or provider-chosen dose of morphine. Participants were eligible for rescue morphine. The primary outcome was the difference in patients' mean reported pain at 60 minutes. Secondary outcomes included total morphine consumption, patient satisfaction, and side effects. Thirty-two patients were enrolled. The lidocaine arm's mean pain NRS at 60 minutes was 5.1 (95% confidence interval [CI] = 3.3 to 6.8) compared with 4.2 (95% CI = 3.0 to 5.4) in the morphine arm, and the absolute difference was 0.9 (95% CI = -1.2 to 2.9). Among participants in the lidocaine and morphine arms, 13% and 38%, respectively, had side effects. Patient satisfaction was similar in both arms (87% and 88%). Lidocaine arm patients averaged 4.5 mg of IV morphine (95% CI = 3.0 to 6.0) compared with 8.4 mg (95% CI = 6.9 to 9.8) in the morphine arm, an absolute difference of 3.9 mg (95% CI = 1.8 to 5.9). We found similar pain relief and satisfaction in both study arms. Lidocaine arm participants had fewer side effects and required less morphine. Lidocaine is a potential opioid-sparing analgesic that deserves further study for severe pain in ED patients.