1 Local anesthetic systemic toxicity (LAST) is estimated to occur in 1 of 1000 local anesthetic administrations (1,2)
It results from supratherapeutic levels of local anesthetic in the bloodstream. Most cases occur in hospitals (61%), while fewer occur in outpatient settings (14%), primarily following upper or lower extremity nerve blocks (19%), naso-oropharyngeal infiltration (17%) or spinal and epidural blocks (11%). (1) Lidocaine is most commonly implicated in LAST events (44%); however, bupivacaine has a lower safety margin and greater cardiac toxicity. (1,2) Ropivacaine has a decreased potential for toxicity. (3)
2 Signs and symptoms of LAST typically appear within 1-5 minutes of local anesthetic administration and include oral numbness, metallic taste, dizziness, drowsiness and disorientation (2)
Severe manifestations may appear up to 6 hours after initial symptom onset, and include seizures, arrhythmias, cardiac arrest and death. (1)
3 Extremes of age, pregnancy, renal disease, cardiac disease and hepatic dysfunction may increase risk of LAST...