Perioperative Lidocaine: Safety First!

To the Editor We read with interest the excellent open mind review of local anesthetic systemic toxicity (LAST). We agree with the author’s recommendation for caution with the perioperative use of lidocaine.1 As early adopters of the opioid sparing parenteral analgesic strategy, we introduced intravenous (IV) lidocaine for acute pain as part of an enhanced recovery after surgery (ERAS) protocol.2 In our own center, it was the paradigm shift toward laparoscopic colorectal surgery combined with the redundancy of epidural analgesia and questionable risks of nonsteroidal anti-inflammatory drugs (NSAIDs) in this surgical model that prompted us to use IV lidocaine.3 Over the past decade, we and others have further refined perioperative protocols and implemented continued training and education of all providers.4 This has allowed for the extension of the perioperative use of IV lidocaine beyond colorectal surgery to spine, trauma, and vascular surgery with ongoing research elsewhere into benefits of lidocaine in oncological surgical models. We agree with the recommendation by Dr Weinberg1 for the need for continuous vigilance and meticulous data collection for the safety of IV lidocaine. We would like to add to that the safety of IV lidocaine has been previously extensively studied over decades of extensive use in cardiology as an antiarrhythmic. Here, it was often used in greater doses, for longer periods, and in patients, we would now consider to be at high risk for adverse outcomes and LAST.5 To ensure patient safety, our own administration protocol, among others, has three important components: the use of commercially available dilute IV lidocaine solutions, dedicated programmed pumps, and specialized valves in the administration tubing (Figure). In our experience, programming errors and inadvertent boluses of IV lidocaine are most likely the causes of LAST. As mentioned by Dr Weinberg,1 the latter was the case of our only serious life-threatening toxicity in our institution.4 To protect against “gravity free flow” from the bag of IV lidocaine, we use a special connector with an antisiphon valve on the short limb of the connector. This valve requires a pressure from a pump to allow drug to pass through the valve and reach the patient. The antireflux valve on the long limb of the connector prevents the drug from flowing retrograde up the main IV tubing should the venous access get partially or completely occluded. If these valves are present, the drug will not flow if the lidocaine tubing is inadvertently removed from the pump nor enter the other fluids being coadministered.6Figure.: Ensuring safety of IV lidocaine infusions: the use of IV PCA Y-connector with an integral antisiphon (to prevent free-flow due to gravity) and an antireflux valve (to prevent reflux into main IV line). IV indicates intravenous; PCA, patient-controlled analgesia. Credit from Eipe et al2; adapted from the original artwork by Perry Ng, Medical Illustrator, Faculty of Medicine, uOttawa.We also concur with the debate by Dr Weinberg1 around the usefulness and efficacy of perioperative lidocaine. While this continues to be studied with good quality clinical trials, there has been lack of overall efficacy being suggested by systematic reviews and meta-analyses. We believe that this requires us to revisit the possible mechanism of analgesic action and identify those patients and procedures where the benefits of lidocaine may outweigh possible risks of LAST. There is well-established evidence and experience from the use of IV lidocaine for chronic pain that confirms its effectiveness for neuropathic pain.7 In our experience, in the acute pain setting, the efficacy of antihyperalgesics is seen in patients and procedures associated with pronociception. Further studies are required to confirm this and the use of diagnostic tools such as the DN4 (Douleur Neuropathique en 4) questionnaire to identify patients who would benefit from IV lidocaine. Overall, we welcome the words of caution, call for vigilance, and the need for a data registry for the perioperative use of IV lidocaine by Dr Weinberg.1 Rather than abandoning the use of IV lidocaine, we believe that there should be efforts at further protocol standardization and expert consensus to improve the safety and outcomes from perioperative lidocaine use. In the meantime, as we and others have suggested, some patients undergoing certain procedures will benefit from the perioperative use of IV lidocaine, and these patients and procedures need to be identified and continually studied. Naveen Eipe, MDJohn Penning, MD, FRCPCDepartment of Anesthesiology and Pain MedicineUniversity of OttawaOttawa, Ontario, Canada[email protected]

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