Intravenous lidocaine versus other analgesia in adult patients with acute pain in the emergency department: a systematic review

Introduction
Acute pain is predominately treated with opioids in the emergency department (ED). However, due to overprescription, misuse and abuse of opioids, opioid addiction has become a national health issue in the United States (US). Alternatives to opioids are necessary to reduce number of opioid related addictions and overdoses. Intravenous (IV) lidocaine has been proven effective to relief pain after abdominal surgery and may be a reliable alternative to opioids for acute pain. The aim of this review is to determine the effect of IV lidocaine compared to other analgesia in adult patients with acute pain in the ED.
Methods
In this systematic review we searched Medline utilizing PubMed for randomized controlled trials (RCTs) published between January 2000 to September 2019. Retrievable RCTs comparing IV lidocaine to other analgesia in adults with acute pain in the ED were eligible for inclusion. The primary outcome was the difference in acute pain relief between IV lidocaine and other analgesics using standardized pain scales. Secondary outcomes were occurrence of adverse events and need for rescue analgesics. The methodological quality of included studies was assessed using the Cochrane risk of bias tool for RCTs.
Results
With our search strategy we found 281 publications. After screening of titles and abstracts, 255 articles were excluded and 26 articles were selected for full text review. We included nine RCTs with a total population of 1077 participants. The risk of bias was considered high in two of the nine studies, unclear in three studies and low in three studies. IV lidocaine was superior to IV morphine in relieving acute pain caused by extremity fractures, critical limb ischemia and renal colic. IV lidocaine had similar results compared to active controls in undifferentiated severe pain and acute limb trauma. In two trials with patients with renal colic and one with acute abdominal pain IV lidocaine was inferior to the active controls but clinically relevant for pain relief. However, IV lidocaine failed to clinically alleviate acute radicular low back pain in one study.
Conclusion
Current evidence suggests IV lidocaine is potentially as effective or superior to other analgesia to relief different types of acute pain in the ED. Thus, IV lidocaine could be an effective opioid sparing analgesic for different types of acute pain. However, due to quality concerns of available evidence and unclear incidence of adverse events using IV lidocaine, more prospective studies must be done before using IV lidocaine in clinical practice for acute pain.