Local Anesthetic Systemic Toxicity

Clinical Presentation

• The first signs of local anesthetic systemic toxicity (LAST) typically manifest as central nervous system excitement, with patients experiencing circumoral numbness, facial tingling, pressured or slurred speech, metallic taste, auditory changes, and hallucinations, which may also be accompanied by hypertension and tachycardia, according to the American Academy of Dermatology 1
• As toxicity evolves, patients may develop seizures or central nervous system depression, as reported by the American Academy of Dermatology 1
• Severe cases may progress to cardiac failure or arrest, as noted by the American Academy of Dermatology 1

Prevention and Management

• To minimize the risk of LAST, the American Academy of Dermatology recommends using appropriate dosing, such as following maximum recommended doses (7 mg/kg lidocaine with epinephrine, 4.5 mg/kg without epinephrine for adults) 1
• If LAST is suspected, the American Academy of Pediatrics recommends stopping administration of local anesthetic immediately and calling for help, as well as securing the airway and administering 100% oxygen 2
• For cardiovascular symptoms, the American Heart Association recommends administering 20% lipid emulsion according to protocol, as well as considering sodium bicarbonate for wide-complex tachycardia and atropine for bradycardia 3

Incidence and Considerations

• Anesthetic toxicity in the dermatologic setting is extremely rare due to typically lower doses used, according to the American Academy of Dermatology 1

Local Anesthetic Systemic Toxicity in Anesthetized Patients

Monitoring and Diagnosis

• The American Society of Anesthesiologists recommends continuous ECG monitoring during regional anesthesia in anesthetized patients, as cardiovascular signs and ECG changes represent late manifestations of toxicity 4
• Unexplained cardiovascular instability during or immediately after local anesthetic administration in an anesthetized patient should trigger immediate consideration of Local Anesthetic Systemic Toxicity (LAST), according to the American Heart Association 5

Treatment

• The American Heart Association recommends immediate lipid emulsion therapy (1.5 mL/kg of 20% solution over 1 minute, followed by infusion of 0.25 mL/kg per minute) for cardiovascular collapse from LAST, which can occur suddenly and may be refractory to standard resuscitation 5, 6