The Use of Intravenous Lidocaine for the Management of Acute Pain Secondary to Traumatic Ankle Injury: A Case Report

Introduction

Sports-related injuries are a frequent cause of visits to the emergency department (ED) across the United States. ¹ These injuries commonly affect older children and young adults as a result of participation in school sports. A majority of these injuries affect the lower extremities with the ankle as the most frequently reported site. A study which reviewed data of injuries documented by 100 high schools in a sports injury surveillance system found that the ankle accounted for 12.3% of all documented injuries. ² According to a recent study, sports-related injuries seen in the ED have risen annually between 2001 and 2013 and are expected to continue trending upward. ³ Most sports-related injuries are not severe enough to require inpatient hospitalization; however, they often lead to acute distress and pain which require prompt treatment with analgesics. ⁴

Acute pain is one of the most adverse stimuli a patient could experience and accounts for 45% to 75% of chief complaints in the ED. ⁵ Furthermore, approximately 22% of patients who presented to the ED required pharmacotherapy for acute pain management. ⁶ Despite this, it has been well documented that acute pain is often inappropriately treated and assessed. ^{5 –9} Opioids have been traditionally used for the management of severe acute pain in the ED; however, there are growing concerns for opioid overuse and misuse. ⁵ Since the beginning of the millennium, there has been an estimated 200% increase in opioid-related deaths. ¹⁰ As a result, there is growing controversy regarding the appropriate selection of analgesic agents, optimal dosing, and need for outpatient therapy which has contributed to changes in prescribing patterns of opioids in the ED. ^11,12 Lidocaine, a class 1b antiarrhythmic, has been utilized as an analgesic agent. ¹³ Its use has been documented for the management of intractable chronic pain caused by cancer, stroke, neuropathies, or nephrolithiasis. ^{14 –21} However, literature describing the use of intravenous lidocaine for the management of acute pain secondary to trauma is limited. ²² We describe a case of the use of intravenous lidocaine for the management of acute pain secondary to ankle fracture in the ED.

Case Report

SK is a 17-year-old Asian male (100 kg, 188 cm), with no medical history, who presented to the ED from school with a chief complaint of acute pain and distress secondary to left ankle and foot deformity (Figure 1). The patient was playing volleyball at school and appeared to have dislocated his ankle from an awkward landing. In the field, no analgesics were provided. The ankle was immobilized and ice packs were applied. On arrival to the ED, the patient was in acute distress, tachypneic, and hypertensive with a blood pressure of 143/80.

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Figure 1.

Initial presentation of the patient’s ankle at the emergency department.

Upon physical examination, skin was intact and the injury appeared to be limited to the ankle which was severely swollen and had limited range of motion. The dorsalis pedis pulse was felt with sensation intact. No other injuries were noted on the left leg. As the patient’s chief complaint was orthopedic in nature, no laboratory specimen was obtained. A baseline electrocardiogram was not performed as patient reported no medical history, and physical examination was unremarkable outside the immediate injury. Medication reconciliation performed by the ED pharmacist revealed no reported use of herbal supplements or over-the-counter medications. Initial X-ray imaging of the ankle noted a possible fracture through the body of the talus and a complete medial subtalar dislocation (Figure 2).

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Figure 2.

X-ray image suggesting a fracture through the body of the talus and complete medial subtalar dislocation.

Morphine 4 mg intravenous push (IVP) was immediately administered for pain control. Fifteen minutes after morphine, the patient was still diaphoretic, in severe distress, and reported a numeric pain score of 10/10. Since there was no response to initial therapy, a decision was made to initiate lidocaine at 1 mg/kg/dose (total dose 100 mg) IV piggyback over 15 minutes for pain.

When the lidocaine infusion was initiated, the patient’s pain score was 10/10. His initial blood pressure was 136/97, heat rate was 110 beats per minute, and respiratory rate was 22 breaths per minute. Five minutes after the completion of the lidocaine infusion, the pain decreased to 6/10. At 20 minutes, the pain score further declined to a 3/10 and remained steady until 75 minutes after initiation of lidocaine. The patient was monitored by a clinical pharmacist for the development of any adverse effects. As the patient’s pain score decreased over time, his elevated blood pressure, tachycardia, and tachypnea resolved. There were no changes in respiratory rate or oxygen saturation, and no arrhythmia was noted on the monitor. The patient only described numbness and a “pins and needles” sensation which were both localized to the ankle. No additional analgesics were required. At 75 minutes after completion of infusion, patient reported his pain score to be 10/10. It is at this point where additional analgesics (ketorolac 30 mg IVP and morphine 4 mg IVP) were concomitantly administered. At 120 minutes after initiation of lidocaine (IOL), SK appeared comfortable and allowed manipulation of his ankle for examination by podiatry. Shortly after, podiatry performed closed reduction in ankle under conscious sedation with fentanyl and midazolam. Posterior splint was applied and SK was discharged home with ibuprofen as needed for pain relief and instructions to schedule a follow-up appointment at the podiatry clinic.

Discussion

Opioids are the most commonly utilized analgesics for the management of severe acute pain in the ED; however, there is growing concern for opioid misuse and overuse. ⁵ Although the risk of recurrent opioid use following a single prescription has traditionally been assumed to be minimal, there are reports which suggest an increased risk of long-term opioid use. ^{23 –25} A retrospective cohort study found that, among previously opioid-naive patients admitted to the ED for low-acuity conditions not expected to result in chronic pain, recurrent use occurred in 17% of patients who filled their opioid prescription compared to 10% in those who received alternative pain relief (adjusted odds ratio: 1.8, 95% confidence interval: 1.3-2.3). ²³ These concerns have led to the exploration of alternative agents for the management of acute pain in the ED.

Lidocaine is a promising opioid alternative for analgesia. As a class 1b antiarrhythmic agent, it exerts its analgesic effects by inhibiting sodium channel depolarization and thereby halting the conduction of action potentials brought on by noxious stimuli. Given systemically, lidocaine’s neuronal blockade exerts a greater effect on nerve fibers which are repeatedly stimulated, such as those that are ischemic. ¹³ As a result, the analgesic effects of lidocaine appear to be selective toward acutely injured tissue versus healthy tissue. This finding was confirmed in a study with healthy volunteers which found that lidocaine produced a significant analgesic effect in deep ischemic pain but not superficial cutaneous pain stimulated by heat, cold, or electricity. ²⁶ Further evidence suggests that the duration of analgesia may exceed the duration of the infusion and the half-life of the drug. ²⁷ These effects were evident in our patient who described the reduction in the pain in his ankle to a pins and needles sensation which he reported was localized to the site of injury. These analgesic effects persisted for additional 75 minutes after the lidocaine infusion had finished which is greater than the reported 10- to 20-minute half-life. ¹³

The analgesic efficacy of lidocaine has been documented in a variety of pain types such as neuropathic, postoperative, oncologic, and chronic opioid-refractory pain. ^{14 –21,28} However, the evidence for the use of intravenous lidocaine for the management of acute pain in the ED is limited. In 2011, a case series documented the successful use of 1.5 mg/kg of lidocaine, administered as a slow IVP, in 7 of 8 patients with renal colic refractory to opioids and nonsteroidal anti-inflammatory drugs. In the patients who responded, colic pain disappeared 30 minutes after injection and did not recur during hospital stay. ²⁰ The following year, a randomized controlled trial by the same authors compared the efficacy of a single dose of 1.5 mg/kg of intravenous lidocaine with 0.1mg/kg of intravenous morphine in 240 patients with renal colic presenting to the ED. Across all measured time intervals, the reported visual analog pain scales were significantly lower in the lidocaine group. ²⁹ Most recently, a case series evaluated the use of intravenous lidocaine in 17 patients who presented to the ED for a variety of conditions, the most common being acute fracture (n = 5), sickle cell crisis (n = 2), acute back pain (n = 2), and abdominal pain (n = 2). The mean dose of lidocaine administered was 148.53 mg with an average pain reduction of 3 points (out of 10). ²²

In the literature, the side-effect profile of lidocaine for management of pain appears to be minimal. The most frequently reported complications include numbness, dizziness, metallic taste, and dysarthia. ^14,28 Although lidocaine has a broad safety margin, serious adverse effects, due to incorrect dosing, have occurred. ^22,28 In the aforementioned case series, a physician ordered 100 mg of lidocaine for a patient who mistakenly received 400 mg after a nurse presented 100 mL of 1% lidocaine to the physician for verification. ²² The patient experienced a seizure, bradycardia, and a brief cardiac arrest but was successfully resuscitated and made a full neurologic recovery. ²² Caution should be used to ensure the proper dispensing of lidocaine to avoid inadvertent drug overdoses. Furthermore, lidocaine should be avoided in patients with severe sinoatrial, atrioventricular, or intraventricular heart blocks unless there is a functioning artificial pacemaker. ³⁰ The patient presented within this report, an otherwise healthy 17-year-old male, reported no systemic adverse effects from the lidocaine infusion and did not develop any arrhythmias.

There are a few potential explanations for the lack of pain relief experienced by the patient after administration of morphine. Although the package insert recommends a starting dose of 0.1 to 0.2 mg/kg (10 to 20 mg for patient SK), as the patient was opioid naive, the decision was made to administer a lower initial dose of morphine 4 mg with the goal of titrating up the dose every 5 to 10 minutes based on patient pain scores in order to avoid potential respiratory depression. ³¹ The decision to titrate morphine instead of administering a larger initial bolus dose is supported by evidence and frequently done in clinical practice. ^32,33 However, as the patient’s pain score remained 10/10, and he was becoming increasingly agitated and hypertensive, intravenous lidocaine was administered instead. The most likely explanation behind lack of analgesic effect of morphine is too low of an initial dose. Another explanation, which is potentially interesting though unlikely to be the cause in our patient, is the interaction between genetic polymorphisms and the analgesic efficacy of opioids. Studies have shown that patients who are carriers of the human µ-opioid receptor gene (OPRM1) 118G allele variant consumed more opioids but reported higher pain scores than their counterparts without the OPRM1 118G allele variant. ^34,35

Conclusion

This case not only adds to the growing body of literature supporting the use of lidocaine for acute fracture pain but also, to the best of our knowledge, is the first report of utilizing intravenous lidocaine for acute pain secondary to complete ankle dislocation. As the literature and prescriber comfort with intravenous lidocaine continues to expand, we expect to see more frequent prescribing of lidocaine for this indication. This case report serves to describe additional clinical experience with intravenous lidocaine for the management of acute pain in the ED.