Local anesthetic systemic toxicity
| Local anesthetic systemic toxicity | |
|---|---|
| Other names: Local anesthetic overdose[1] | |
 | |
| Bupivacaine with epinephrine | |
 | |
| Specialty | Toxicology |
| Symptoms | Numbness around the mouth, metallic taste, muscle twitching, confusion[2] |
| Complications | Seizures, heart arrythmias[1] |
| Usual onset | Within minutes[1] |
| Risk factors | Injection into a blood vessel, liver problems, heart disease, pregnancy, larger doses of medication[1][3] |
| Diagnostic method | Based on symptoms, supported by ECG[1] |
| Differential diagnosis | Anaphylaxis, panic attack[1] |
| Treatment | Supportive care, 20% lipid emulsion, benzodiazepines, ECMO[2][1] |
| Frequency | Uncommon[3] |
| Deaths | 0.4% of cases[3] |
Local anesthetic systemic toxicity (LAST) are potentially severe side effects that may occur due to local anesthetics.[3] Symptoms may include numbness around the mouth, a metallic taste, muscle twitching, or confusion.[2] Half of cases begin within 1 minute and three quarters within 5 minutes.[1] More severe complications may include seizures or heart arrythmias.[1]
The greatest risk factor is injection into a blood vessel;[2][1] though cases have been described with topicial applications.[3] Other risks include liver problems, heart disease, pregnancy, low muscle mass, and larger doses of medication.[1][3] Bupivacaine has a high risk of toxicity compared to lidocaine.[1] Diagnosis is based on symptoms; though, may be supported by an ECG.[1]
Treatment begins with airway and breathing support.[1] Benzodiazepines, such as midazolam, may be used for seizures.[2] 20% lipid emulsion is recommended.[2] In cardiac arrest, 10% the usual epinephrine dose should be used.[2] ECMO may also be an option.[2]
LAST is uncommon with rates varying from 0 to 8 per 1,000 depending on the procedure.[1][3] Those who are very young or old may be more frequently affected.[1][3] Of reported cases abouy 0.4% die.[3] Toxicity from local anesthetics has been described since 1887 when cocaine was in use; though, was also reported with procaine after its introduction in the early 1900s.[4]
Cause
High doses of medications increase the risk.[3]
The maximum doses for lidocaine are 5 mg/kg without epinephrine and 7 mg/kg with epinephrine.[3] While with bupivacaine the maximum is 2 mg/kg without epinephrine and 3 mg/kg with epinephrine.[3] The maximum dose should be based on ideal body weight.[3]
Treatment
Initial management involves supportive care, which may include providing oxygen and ventilation.[3] Intravenous fluids and norepinephrine may also be required to maintain blood pressure.[3] Vasopressin use is not recommended.[3] CPR may be carried out in the standard fashion; though, lower doses of epinephrine at less than 1 ucg/kg are recommended.[3]
Lipid emulsion is recommended in those with significant symptoms including cardiac arrest.[3] It is given as 100 mL over 2 to 3 minutes of a 20% solution in someone who is at least 70 kg or 1.5 mL/kg.[2][3] This dose may be repeated or followed by an infusion of 250 mL over 15 to 20 minutes.[3] The maxmimum dose is 12 mL/kg for lipid emulsion.[3]
Amiodarone maybe used if required, but calcium channel blockers, beta blockers, and procainamide should be avoided.[3]
References
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 Mahajan, A; Derian, A (January 2025). "Local Anesthetic Toxicity". StatPearls. PMID 29763139.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 Borshoff, David (2018). The Resuscitation Crisis Manual. Leeuwin Press. ISBN 9780648270201.
- ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 3.20 3.21 Long, B; Chavez, S; Gottlieb, M; Montrief, T; Brady, WJ (September 2022). "Local anesthetic systemic toxicity: A narrative review for emergency clinicians". The American journal of emergency medicine. 59: 42–48. doi:10.1016/j.ajem.2022.06.017. PMID 35777259.
- ↑ Drasner, K (March 2010). "Local anesthetic systemic toxicity: a historical perspective" (PDF). Regional anesthesia and pain medicine. 35 (2): 162–6. doi:10.1097/AAP.0b013e3181d2306c. PMID 20216034.