Local anesthetic toxicity
Local anesthetic toxicity is related to high plasma levels of local anesthetic found in:
1 -drug overdose.
2-direct intravascular injection.
3 -rapid absorption/injection into a highly vascular area, e.g.
intercostals.
4 -continuous infusion of local anesthetic.
4 -cumulative effect of multiple injections.
Maximum recommended doses of common agents
Bupivacaine
2mg/kg
with vasoconstrictor 2mg/kg
Levobupivacaine
2mg/kg
Ropivacaine
3mg/kg
Lidcaine
3mg/kg
with vasoconstrictor 6mg/kg
Prilocaine
6mg/kg
with vasoconstrictor 8mg/kg
Cocaine
3mg/kg
Symptoms and signs of toxicity:
Mild toxicity
Tingling around the mouth
Metallic taste
Tinnitus
Visual disturbance
Slurred speech
Moderate toxicity
Altered conscious state
Convulsions
Coma
Potentially fatal toxicity
Respiratory arrest
Cardiac arrhythmias
Cardiovascular collapse
Treatment:
Stop injection or infusion as appropriate.
Treatment of adverse local anesthetic toxicity depends on their severity.
Minor reactions can be allowed to resolve spontaneously.
Local anesthetic-induced seizures should be managed by protecting the airway and providing oxygen.
Seizures may be terminated with intravenous thiopental, midazolam, or prpofol.
If local anesthetic intoxication produce cardiac arrest, the guide lines for advanced cardiac life support (ACLS) are reasonable.
Amidarone and vasopressin are suggested for lidocaine and epinephrine, respectively.
With unresponsive bupivacaine cardiac toxicity, intravenous lipid or cardiopulmonary bypass may be considered.
