Max amounts of local anesthetic:
For a 70 kilogram, that means 35 mls of 1% Lidocaine, 49 mls of !% Lidocaine w/ epi, etc.
Mechanism of toxicity; sodium channel blockade effects block cardiac myocyte function and electrophysiology, resulting in arrhythmias. Intravascular absorption of LA also may travel to the CNS, causing its neurologic effects.
Symptoms: a prodrome of perioral numbness, tinnitus, agitation, dysarthria, and confusion. Followed by possible seizures and coma.
Cardiovascularly, patients initially present with hypertension and tachycardia, which progresses to bradycardia and hypotension. This eventually progresses to ventricular arrhythmias and asystole.
The majority of adverse events occur within 1 minute of injection, but some cases may more than 1 hour after injection.
Bupivicaine’s higher toxicity is linked to its higher lipophilicity.
Toxicity is more common in this with hepatic and renal dysfunction, and those with heart disease and heart failure are at increased risk, as are those at the extremes of age, and in the ED setting are most common in peripherals nerve blocks
Prevention:
Always aspirate before injection of local anesthetic.
Treatment:
