Regional Anesthesia: Local Anesthetic Toxicity (LAST)

Definition: Systemic adverse reaction resulting from high blood concentrations of local anesthetics.

Etiology:Direct IV injection of local anesthetics or large concentration absorbed into the circulation very quickly. Bupivicaine is a local anesthetic that is particularly cardiotoxic.

Clinical Manifestations:

System

Clinical Signs and Symptoms

Neurological

Metallic taste in mouth, perioral numbness/tingling

Tinnitus

Mental status changes

Seizure (late finding)

Visual changes

Respiratory

Respiratory depression

Loss of airway reflexes

Obstruction

Cardiovascular

Initial hyperdynamic followed by cardiovascular collapse

Dysrhythmias

Conduction abnormalities


Treatment:

If you suspect LAST, CALL FOR HELP. Stop any sources of local anesthetic. Most hospitals have a “LAST KIT” that has the necessary supplies.

Treat with lipid emulsion (Intralipid) 20%. Initial bolus is 1.5ml/kg rapidly, followed by infusion.

Problem

Treatment

Airway

100% FiO2

Advanced airway if necessary

Avoid hyperventilation (decreases seizure threshold)

CNS

Treat seizures with benzodiazepines (ex midazolam)

Can consider small doses of propofol

Cardiovascular

Treat as per ACLS algorithm; reduce epiniephrine dose

Prolonged resuscitation may be necessary

Avoid vasopressin, calcium channel blockers, beta blockers, additional local anesthetics


Post-operative disposition:Send to ICU. Requires additional monitoring.


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