Local anesthetic systemic toxicity

Local anesthetic systemic toxicity (LAST) is a potentially life-threatening reaction caused when local anesthetic concentrations in the blood become high enough to impair the nervous and cardiovascular systems.

Voltage-gated sodium channel: A membrane protein that opens in response to voltage changes and allows sodium ions to cross cell membranes. Local anesthetics block these channels in nerves and cardiac tissue when systemic concentrations rise.
Regional anesthesia: Anesthesia that blocks sensation in a defined region of the body while the patient may remain conscious. Regional techniques commonly require local anesthetics and therefore carry a risk of LAST.
Intravascular injection: Accidental delivery of a substance directly into a blood vessel rather than the intended tissue or space. An unintended intravascular injection can produce an abrupt, high blood concentration of local anesthetic.
Local anesthetic systemic toxicity and methemoglobinemia: A comparison of two adverse effects of local anesthetics: systemic neural and cardiac toxicity, and impaired oxygen carriage from oxidized hemoglobin. Prilocaine-related methemoglobinemia can resemble hypoxia but has a different mechanism and treatment.
Local anesthetic: A drug that temporarily blocks nerve conduction, commonly by inhibiting voltage-gated sodium channels. LAST is a systemic adverse reaction to drugs ordinarily used to block sensation locally.
Local anesthetic systemic toxicity checklist: A clinical aid outlining recognition and emergency management of local anesthetic systemic toxicity. A checklist supports rapid, coordinated treatment when LAST is suspected.
Local anesthetic overdose: Exposure to a local anesthetic in an amount sufficient to cause harmful effects. Overdose is one route to the excessive systemic concentration that defines LAST.
Allergic reaction to local anesthetics: An immune-mediated adverse reaction to a local anesthetic or an ingredient in its formulation. Allergy is distinct from the dose-related pharmacological toxicity that causes LAST.
Central nervous system toxicity: Injury or dysfunction of the brain and spinal cord caused by exposure to a harmful substance. Early LAST often produces neurological symptoms before severe cardiovascular effects.
Lipid rescue: Emergency use of intravenous lipid emulsion to treat severe toxicity from certain drugs, including local anesthetics. Lipid rescue is incorporated into LAST response protocols for severe cases.

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