Clinical characteristics, treatment, and outcomes of local anesthetic systemic toxicity: a 10-year retrospective study.

BACKGROUND

Local anesthetic systemic toxicity is a rare but potentially life-threatening complication of local anesthetic use. This study aimed to describe the characteristics of patients with local anesthetic systemic toxicity and to identify initial clinical prognostic factors.

METHODS

A retrospective cohort study of patients diagnosed with local anesthetic systemic toxicity from January 2013 to December 2022 was conducted using data from the Ramathibodi Poison Center Toxic Exposure Surveillance System, Thailand.

RESULTS

One hundred and forty-three patients were included, with a median age of 41.5 years (IQR: 27.0-56.0 years). Lidocaine was the most commonly implicated local anesthetic (89.5%). The most frequent routes of administration were local infiltration (59.4%) and intravenous (15.4%). Neurological symptoms (perioral numbness, seizures, or coma) were the most common initial presentations (78.3%), followed by cardiovascular symptoms (43.4%), including chest pain, palpitations, hypotension, and cardiac arrest; cardiac arrest occurred in 10.5% of cases. Intravenous lipid emulsion therapy was administered in 12.6% of patients, and the median time from symptom onset to administration was 63 min (IQR: 48-90 min). Adverse effects of intravenous lipid emulsion (acute respiratory distress syndrome and fat overload syndrome) occurred in two of 18 (11.1% [95% CI:3.4-26%]) recipients. A multivariate analysis identified intravenous administration of local anesthetic (OR: 5.59; 95% CI: 1.53-20.33), the initial presence of coma (OR: 12.0; 95% CI: 2.96-48.60), hypotension (OR: 5.23; 95% CI: 1.34-20.29), and cardiac arrest (OR: 210; 95% CI: 22-1,919) as independent predictors of mortality.

DISCUSSION: Seizures were the most frequent initial neurological presentation in our study, followed by cardiovascular features, particularly hypotension and palpitations, which is consistent with previous reports of local anesthetic systemic toxicity.

CONCLUSIONS

In our study, the presence of hypotension, coma, and cardiac arrest at presentation and intravenous administration of local anesthetic was strongly associated with severe outcomes and increased mortality. Although intravenous lipid emulsion therapy has shown clinical efficacy, delayed access to this treatment remains a considerable barrier, particularly in rural or resource-limited settings.