Significant Rise in Lidocaine-Related Poisonings and Fatalities in the U.S.

A recent analysis of data from the National Poison Data System (NPDS) indicates that incidents of poisoning and fatalities associated with the local anesthetic lidocaine have nearly tripled in the United States over the last decade. This trend contrasts sharply with a decline in poisonings from other types of local anesthetics during the same period, as reported in a study published in the journal Regional Anesthesia & Pain Medicine.

Local anesthetics are commonly employed for pain management but pose a risk of systemic toxicity known as Local Anesthetic Systemic Toxicity (LAST). In 2010, various professional organizations issued guidelines aimed at managing these risks. Researchers sought to evaluate the impact of these recommendations by comparing data from two distinct periods: 2001-2010 and 2010-2022. They analyzed reports submitted to poison control centers across the U.S. from 1983 to 2022.

The study assessed annual reports of poisoning and death caused by local anesthetics, categorizing them into lidocaine and non-lidocaine types. It also examined the total number of poisoning cases from all substances. From 1983 to 2022, there were 74 reported deaths linked to local anesthetics, comprising a small fraction of the total 203,853 reports of local anesthetic poisonings. In contrast, there were 39,913 deaths reported among 79,360,369 cases of poisoning from all causes.

Between 2001 and 2022, only 0.1% of lidocaine poisoning reports resulted in death, compared to 0.01% for non-lidocaine cases. Notably, from 2010 onwards, the relative risk of local anesthetic poisoning decreased by 23%, primarily due to a 50% drop in non-lidocaine poisoning reports. Conversely, reports of lidocaine poisoning surged by over 50%, with cases increasing from 1,600 in 2016 to 2,500 in 2021.

The risk of death related to local anesthetics more than doubled between 2011 and 2022 in comparison to the prior decade, largely due to an increase in lidocaine-related fatalities. A detailed analysis of 59 individual death cases revealed that 32 occurred before 2010 (average age 25) and 27 between 2011 and 2022 (average age 55). In the earlier group, lidocaine was involved in two-thirds of the cases, whereas in the latter group, it accounted for 82% of the deaths.

While the overall proportion of deaths occurring in operating rooms decreased from 47% before 2010 to 15% afterwards, prehospital deaths -- occurring in emergency medical services or emergency departments -- rose significantly from 7% to 31%. Additionally, deaths attributed to intravenous lidocaine escalated from 3% to 27% of total cases.

The majority of fatalities involving lidocaine were linked to dosages that exceeded the recommended maximum of 500 mg, with some cases reporting doses as high as 2,000 mg. These overdoses often occurred in emergency settings, frequently leading to tragic outcomes. Recent case studies indicate that even minimal amounts of intravenous lidocaine can result in severe side effects in vulnerable patients.

To mitigate the cardiac and neurological consequences of lidocaine toxicity, lipid emulsion therapy is advised. However, the analysis of individual cases indicated that this treatment was applied inconsistently and often too late, contributing to patient mortality. The researchers suggest that the therapy may not suffice for patients who have received extremely high doses of intravenous lidocaine.

The authors of the study acknowledge certain limitations, including potential under-reporting to the NPDS and incomplete clinical data. They propose that comparing poisonings at healthcare facilities may provide a more accurate perspective. Notably, non-lidocaine poisoning reports constituted 85% of total poisoning cases in healthcare settings between 2001 and 2002 but fell to 31% between 2021 and 2022, suggesting that the decline in local anesthetic poisonings may be underestimated.

While these findings should be interpreted with caution due to the lack of comprehensive population-level exposure data, they underscore the urgent need for improved guidelines on lidocaine utilization, heightened awareness regarding the dangers of excessive doses, and enhanced strategies for preventing and managing severe toxicity related to lidocaine.