Pain management in the ED has become a balancing act. EPs must continually balance adequate pain management with the risks of opioids prescribing. As providers reach into their pain management toolbox it is always nice to have as many options as possible because one size does not fit all. Specifically for the management of acute renal colic, IV preservative-free (cardiac) lidocaine has been gaining popularity as a potential alternative when opioids are unable to get job done or are contraindicated due to co-morbidities or a history of addiction. Is it safe? Does it work?
Background and literature
Let’s back up a little.
In the early 2000s, research was conducted on IV lidocaine therapy for the management of severe and intractable neuropathic pain in cancer patients. It was found to be effective and, despite concerns about side effects, safe with little to no toxicity. Patients reported improved pain and quality of life.1 It then became of a drug of interest for post-operative pain relief and was found to reduce post-operative pain, opioid consumption, length of stay, nausea/vomiting, and ileus recovery time.2,3
During this time EPs in Iran became interested in evaluating lidocaine’s efficacy in treating the pain associated with renal colic. As there are no IV NSAIDs in Iran, practitoners were left treating most cases with only IV opioids. Case reports and a case series then led to a randomized controlled trial in 2012 that compared IV lidocaine at 1.5 mg/kg (max of 200 mg) over 10 minutes to IV morphine at 0.1 mg/kg for the management of renal colic pain in the ED. Both groups received IM diclofenac. At 5, 10, 15, and 30 minutes post-administration, the IV lidocaine group had significantly lower pain scores (p=0.0001). There was no clinically significant toxicity noted with the most common side effect being nausea (7.5%) in the opioid group and transient dizziness (8.3%) in the lidocaine group.4
Why does lidocaine work?
Lidocaine is an amide local anesthetic that non-competitively blocks fast voltage gated sodium channels exerting an analgesic, anti-inflammatory, and anti-hyperalgesic effect.5,6 By inhibiting the depolarization of the nerve’s cell membrane, lidocaine prevents the transmission of afferent pain signals thus altering sympathetic smooth muscle tone.7 This analgesic effect may be similar to that of NSAIDs thus decreasing ureteral spasm.8
Dosing of IV lidocaine
The analgesic dose of lidocaine is 1.5 mg/kg given over 10 minutes, which is significantly lower than the toxic dose of 4 mg/kg. However, a thorough history and proper patient selection based on the contraindications is imperative prior to the administration of lidocaine
One LAST thing: Local Anesthetic System Toxicity concerns
Local anesthetic systemic toxicity (LAST) can lead to a variety of complications ranging from transient neurologic deficits to seizure to cardiovascular collapse. Contraindications to IV lidocaine administration include:9
- Allergy to lidocaine
- History of seizure
- Hepatic or renal insufficiency
- Severe coronary artery disease
- History of AV heart block
- Cardiac arrhythmia
Cardiac monitoring is recommended during administration and for approximately 30-60 minutes post-administration, especially for any patients with a concerning history of cardiac disease.6,10 It is important to have intralipid emulsion therapy readily available to immediately administer if there is any concern for the development of cardiac manifestations of LAST (prolonged PR, widened QRS, hypotension, arrhythmia, cardiac arrest).6
Dosing of intralipid emulsion therapy
- Bolus: 1.5 mL/kg 20% lipid emulsion
- Infusion: Follow with a 0.25 mL/kg/min infusion that should be continued until there is cardiovascular stability for 10 minutes
- If cardiovascular stability is not achieved
- Repeat bolus 1.5 mL/kg 20% lipid emulsion
- Increase the infusion to 0.5 mL/kg/min
- Propofol is not a substitute for intralipid therapy
Yes, we need more evidence about IV lidocaine for acute renal colic, because most of the evidence available regarding IV lidocaine surrounds peri-operative use. However, by extrapolating that data along with the limited ED literature, IV lidocaine may be considered a safe and effective analgesic for renal colic. Administer 1.5 mg/kg lidocaine IV over 10 minutes via a smart pump along with ketorolac 15 mg IV for a synergistic multimodal approach.
Note that this is NOT for every patient with presumed renal colic, but rather to provide you with an alternative when faced with difficult cases and management dilemmas, especially when trying to avoid opioids. IV lidocaine should be another tool in your pain management toolbox.