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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