Is Intralipid (lipid emulsion) required in a clinic using local anesthetics to treat local anesthetic systemic toxicity?

From the Guidelines

Intralipid (lipid emulsion) is strongly recommended to be readily available in clinics using local anesthetics to treat local anesthetic systemic toxicity (LAST), as it is considered best practice for managing LAST. The decision to stock intralipid depends on several factors including the types and doses of local anesthetics used, proximity to emergency services, and facility risk assessment. According to the most recent guidelines from the American Heart Association, published in 2023 1, the administration of intravenous lipid emulsion is recommended for local anesthetic poisoning, with a suggested dosing of 1.5 mL/kg as an initial bolus followed by an infusion of 0.25 mL/kg/min for at least 10 minutes after hemodynamic stability is achieved. Intralipid works by creating a "lipid sink" that extracts lipophilic local anesthetic molecules from tissue and by providing a source of fatty acids to reverse mitochondrial dysfunction and improve cardiac function during toxicity. While not legally mandated everywhere, having intralipid readily available represents prudent clinical practice in settings where significant amounts of local anesthetics are administered. Key considerations for the use of intralipid in managing LAST include:

• Immediate access to 20% lipid emulsion
• Recommended dosing of 1.5 mL/kg as an initial bolus
• Infusion of 0.25 mL/kg/min for at least 10 minutes after hemodynamic stability is achieved
• Decision to stock intralipid based on factors such as types and doses of local anesthetics used, proximity to emergency services, and facility risk assessment. The American Heart Association guidelines also recommend the use of benzodiazepines to treat seizures associated with local anesthetic systemic toxicity 1. Overall, the availability of intralipid is crucial in clinics using local anesthetics to ensure prompt and effective management of LAST, prioritizing patient morbidity, mortality, and quality of life.

From the Research

Local Anesthetic Systemic Toxicity Treatment

• Local anesthetic systemic toxicity is a rare but potentially fatal complication of regional anesthesia 2, 3, 4, 5, 6
• The use of lipid emulsion, such as Intralipid, has been increasingly recommended as a treatment for local anesthetic systemic toxicity 2, 3, 4, 5, 6

Mechanism of Action

• The exact mechanism of action of lipid emulsion in treating local anesthetic systemic toxicity is unclear, but it is thought to involve increasing metabolism, distribution, or partitioning of the local anesthetic away from receptors into lipid within tissues 2
• Lipid emulsion may also have a direct effect on cell metabolism, involving survival cell pathways, and functional properties, as well as direct hemodynamic parameters 3

Efficacy of Lipid Emulsion

• There is evidence to suggest that lipid emulsion is effective in reversing the cardiac and neurologic effects of local anesthetic toxicity 2, 4, 5, 6
• A systematic review of 113 studies and reports found that lipid emulsion appeared to be effective for reversal of cardiovascular or neurological features in some cases of local anesthetic toxicity, but the quality of evidence was very low 6
• The majority of patients in case reports reviewed were unresponsive to initial management of local anesthetic toxicity with standard resuscitative measures, but all recovered completely after receiving lipid emulsion therapy 2

Recommendations for Use

• Lipid emulsion should be considered among the primary treatments for local anesthetic toxicity and be made readily available in every facility's operating or procedure room 4
• An initial bolus dose of 1.5 mL/kg followed by an infusion of 10 mL/min as soon as local anesthetic toxicity is suspected seems most beneficial 2
• Lipid emulsion cannot substitute for standard resuscitation protocol, but should be added to it 3