Abstract
To the Editor:
It was with great interest that we read the report by Dryden et al 1 regarding their use of intravenous (IV) lidocaine to treat acute pain due to musculoskeletal injury in an austere setting, as there is no precedent for out-of-hospital IV lidocaine administration for acute pain that we can identify. Treatment of pain is often overlooked, and can be critical to facilitating procedures or patient evacuations. Given the range of available modalities, it can be as much art as science. 2 Appropriate investigation of new applications of classic pain control medications, such as the use of aqueous lidocaine in IV rather than infiltrative application, can be of benefit to growing the knowledge of our field. However, we are concerned that the treatment described here sets a dangerous standard worthy of reproach.
The authors describe 2 cases of musculoskeletal pain treated with 1 mg·kg-1·h-1 of IV lidocaine infusion to preserve the limited supply of ketamine available in a remote clinic. Anesthesia guidelines describe the use of IV lidocaine for in-hospital pain management as a “high-risk” practice. 3 Lidocaine has a narrow therapeutic index, and local anesthetic systemic toxicity (LAST) caused by accidental overdose can incite arrhythmia, altered mental status, and cardiac arrest. 4 In a systematic review of the use of IV lidocaine in hospital application (generally 1–2 mg·kg-1 slow IV bolus or 1 mg·kg-1·h-1 IV infusion), of the 289 patients treated with IV lidocaine, 44 adverse events were reported of which 36 (12.4%) were “serious,” including altered mental status and cardiac dysrhythmias. 5 For this reason, the same guideline cited by the authors states that 20% lipid emulsion, the accepted treatment for LAST, “should be readily available wherever IV lidocaine is used.” 3 The authors’ introduction suggests that they find potential benefit in the use of IV lidocaine in a low-resource setting to which this guideline may not apply, but we think their report better highlights an example of a setting in which the use of IV lidocaine is not appropriate.
We note that both patients described by Dryden et al 1 experienced tinnitus, a prodromal symptom of LAST.4,6,7 This is of critical concern as this clinic did not have lipid emulsion available and, as such, could not have appropriately treated life-threatening complications if they arose. Additionally, both described cases were of isolated musculoskeletal injuries (tibia/fibula fracture and isolated rib fractures) that are amenable to landmark-based nerve blocks, which would have posed fewer risks to their patients. Further, there was no need to assume the risk of LAST and its attendant morbidity and mortality as the clinic had access to alternative pain medications as well as “a nearby location…[with] access to additional care.” No discussion of informed consent is provided, and so the reader is left to wonder whether these patients knowingly accepted the risk of IV lidocaine infusion in favor of available alternatives.
In an effort to “[avoid] many of the detrimental effects that accompany alternative analgesics,” Dryden et al 1 needlessly subjected their patients to the risk of serious harm from a therapy with viable and available alternatives. As a field, we should not condone such unnecessary risk, which is not only unsupported by prehospital/austere evidence but also opposed by available guidelines. This case report highlights the extreme hazard of employing IV lidocaine without appropriate resources and reminds us that in the treatment of pain, as always, primum non nocere.