Randomized double-blind study of intravenous tocainide versus lidocaine for suppression of ventricular arrhythmias after cardiac surgery

Evaluating the Safety of Continuous Infusion Lidocaine for Postoperative Pain

OBJECTIVES

The aim was to evaluate the safety of intravenous lidocaine for postoperative pain and the impact on opioid requirements and pain scores.

MATERIALS AND METHODS

This was a single-center, retrospective, single-arm analysis of adult patients who received intravenous lidocaine for postoperative pain from January 2016 to December 2019. Patients were excluded if they received lidocaine for any indication other than pain or if lidocaine was only given intraoperatively. The primary outcome of this analysis was to determine the incidence of adverse effects (AEs) and the reason for discontinuation of lidocaine. Secondary outcomes included median daily pain scores (visual analog scale and Critical-Care Pain Observation Tool) and opioid consumption (daily morphine milligram equivalents) 24 hours before infusion and during day 1.

RESULTS

A total of 452 patients were evaluated of which 298 (65.9%) patients met inclusion criteria. Of the 154 patients excluded, 153 did not receive lidocaine postoperatively. The median duration of infusion was 34 [20:48] hours with a median initial and maintenance rate of 1 mg/kg/h dosed on ideal body weight. In our analysis, 174 (58.4%) patients had a documented AE during infusion and 38 (12.8%) had lidocaine discontinued because of an AE. The most common AE was nausea in 62 (20.8%) patients and the most common reason for discontinuation was confusion in 8 (2.7%) patients. Daily morphine milligram equivalents (P<0.001) and visual analog scale (P<0.001) significantly decreased when comparing 24 hours before infusion and day 1.

CONCLUSION

Although a majority of patients receiving lidocaine for postoperative pain experienced an AE, this did not result in discontinuation in most patients.

Neuropsychiatric Side-Effects of Lidocaine: Examples from the Treatment of Headache and a Review

Lidocaine has been used in treatment of patients with refractory headache. Personal observations of neuropsychiatric toxicity in these patients led us to review our cases and the literature systematically for lidocaine side-effects, especially neuropsychiatric symptoms. In our series of 20 patients, side-effects were observed in all, the most frequent being neuropsychiatric (75%) and cardiological (50%). When reviewing published series on intravenous lidocaine use, reports of side-effects range from 0 to 100%, with neuropsychiatric symptoms being reported in 1.8–100%. Thirty-six case reports of lidocaine-induced psychiatric symptoms were also analysed. Psychiatric symptoms of toxicity were similar in most patients, despite their differing ages, pathologies, co-therapies and lidocaine dosages. In conclusion, lidocaine neuropsychiatric toxicity has a well-recognized stereotypical clinical presentation that is probably unrecognized in headache series. As lidocaine represents an emerging alternative therapy in headache, particularly in short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing, clinicians and patients should be aware of the extent of this problem.