From the Guidelines
The treatment for Local Anesthetic Systemic Toxicity (LAST) primarily involves administering intravenous lipid emulsion therapy, with a recommended protocol of an initial bolus of 1.5 mL/kg over 1 minute, followed by an infusion of 0.25 mL/kg/min for 30-60 minutes, as supported by the most recent guidelines from the American Heart Association in 2023 1. The key steps in managing LAST include:
- Immediately stopping local anesthetic administration
- Calling for help and initiating airway management if needed
- Administering 20% lipid emulsion as described above
- Treating seizures with benzodiazepines, as recommended by the American Heart Association 1
- Managing cardiac arrhythmias as needed, with consideration of sodium bicarbonate for life-threatening wide-complex tachycardia and atropine for life-threatening bradycardia, as suggested by the American Heart Association guidelines 1 The use of lipid emulsion therapy is based on its ability to create a "lipid sink" that extracts lipophilic local anesthetics from tissue and provides a source of fatty acids to reverse mitochondrial dysfunction, as discussed in the context of LAST management 1. It is essential to avoid using lidocaine, beta-blockers, calcium channel blockers, and vasopressin in the treatment of LAST, as these can exacerbate the condition, and instead focus on supportive care and the administration of lipid emulsion therapy, as outlined in the guidelines from the American Heart Association in 2023 1.
From the Research
Treatment for Local Anesthetic Systemic Toxicity (LAST)
The treatment for Local Anesthetic Systemic Toxicity (LAST) involves several key steps, including:
- Halt administration of local anesthetic immediately if systemic toxicity is suspected 2
- Request assistance and secure venous line, airway, and administer 100% oxygen 2
- If necessary, tracheal intubation and artificial respiration should be performed 2
- Benzodiazepines are recommended to treat convulsions 2
- Administration of 20% lipid emulsion according to the protocol is recommended to treat severe hypotension and arrhythmia 2, 3, 4
- Oxygenation, ventilation, and advanced cardiac life support are the first priorities in treatment 3
- Lipid emulsion therapy should be given at the first sign of serious systemic toxicity with an initial bolus dose of 100 ml for adults weighing greater than 70 kg and 1.5 ml/kg for adults weighing less than 70 kg or for children 3
- Maintenance of circulation and intravenous lipid emulsion therapy are also crucial in the management of LAST 5, 6
- The use of epinephrine and vasopressin should be tailored to specifics of an episode of LAST, and doses should be kept as low as possible while still achieving the desired effects 4
Key Considerations
- The incidence of local anesthetic systemic toxicity is 1-11 cases per 10,000 2
- Infants, patients with decreased liver function, and low cardiac output are vulnerable to systemic toxicity 2
- The management of LAST includes adequate oxygenation and ventilation, seizure termination, and maintenance of circulation 5
- Local anesthetic systemic toxicity is a potentially lethal condition with protean manifestations, and anesthesiologists must understand its risks, prevention, and safe management 5