Eight studies met inclusion/exclusion criteria, six RCTs and two case series, for a total of 536 patients. The causes of pain included radicular low back pain, renal colic, critical limb ischemia, and migraine headaches.

• Efficacy: There were six RCTs included and two case series for efficacy. Among the six RCTs, IV lidocaine had efficacy equivalent to that of active controls in two studies and was better than active controls in two other studies. In particular, IV lidocaine had pain score reduction comparable to or higher than that of IV morphine for pain associated with renal colic and critical limb ischemia. Lidocaine did not appear to be effective for migraine headache in two studies.
• Safety: There were 20 adverse events reported by six studies among 225 patients who received IV lidocaine in the emergency department, 19 non-serious events and one serious event related to an accidental overdose of lidocaine (rate 8.9 percent, 95 percent confidence interval 5.5 to 13.4 percent for any adverse event; and 0.4 percent, 95 percent confidence interval 0 to 2.5 percent for serious adverse events).

(click for larger image) Certainty in the Evidence

Evidence-Based Medicine Commentary

1. Search Strategy: This was an excellent example of how to do a good search.
2. Quality of Evidence: The quality of evidence was low due to methodological problems, risk of bias, inconsistency, small studies, and imprecision. There was so much heterogeneity that they correctly did not perform a meta-analysis.
3. Hierarchy of Evidence: There is a pyramid of evidence for evidence-based medicine (see Figure 1). On the bottom is background information and expert opinion and at the top is the systematic review. However, in this case, when the quality of evidence is so poor, I would suggest a well-done RCT gets us closer to the truth than a number of low-quality RCTs and observational studies.

There is limited current evidence to define the role of intravenous lidocaine as an analgesic for patients with acute renal colic and critical limb ischemia pain in the ED.

Bottom Line

The routine use of IV lidocaine for analgesia in the emergency department cannot be supported based on the current strength of available evidence.

Case Resolution

The patient is advised that physicians have tried lidocaine as a non-opioid analgesic, but that the research really does not support its effectiveness or safety at this time. The physician recommends IV morphine again, and the patient arranges another way home.

Thank you to Dr. Sergey Motov, an emergency physician in the department of emergency medicine at Maimonides Medical Center in New York City.