Experience Summary

In this experience, observe the anaesthetic team manage a case of local anaesthetic toxicity in a patient with an ongoing epidural infusion.

Clinical Context

Local anaesthetic systemic toxicity (LAST) is a rare but potentially life-threatening complication of regional anaesthesia, including epidural infusions. It occurs when plasma concentrations of local anaesthetic agents such as Bupivacaine or Ropivacaine rise to toxic levels, either due to inadvertent intravascular administration, excessive dosing, or reduced clearance. In the context of an ongoing epidural infusion, toxicity may develop insidiously, making vigilance essential.

Signs of LAST

Clinically, LAST typically presents with early neurological symptoms such as circumoral numbness, tinnitus, metallic taste, agitation, or confusion. These may progress to seizures and reduced consciousness. Cardiovascular toxicity can follow or occur concurrently, manifesting as arrhythmias, conduction block, hypotension, and in severe cases, cardiac arrest. Bupivacaine is particularly cardiotoxic due to its strong sodium channel binding.

Management of LAST

Management begins with immediate recognition and cessation of the epidural infusion. The anaesthetist should call for help and initiate an ABC approach. Airway management is critical; high-flow oxygen should be administered, and early intubation may be required if there is reduced consciousness or ongoing seizures. Avoidance of hypoxia, hypercapnia, and acidosis is essential, as these exacerbate toxicity. Seizures should be treated promptly with benzodiazepines such as midazolam. Large doses of propofol should be avoided in haemodynamically unstable patients due to its myocardial depressant effects. Cardiovascular instability should be managed with cautious use of small-dose adrenaline, along with intravenous fluids. Standard advanced life support protocols apply, but modifications are recommended in LAST. A key component of treatment is intravenous lipid emulsion therapy, typically using Intralipid. This should be administered early in significant toxicity, with an initial bolus (e.g. 1.5 mL/kg of 20% lipid emulsion) followed by an infusion. Lipid therapy acts as a “lipid sink,” sequestering lipophilic local anaesthetic molecules and reducing their bioavailability at target tissues, particularly the heart and brain. Continuous monitoring is essential, including ECG, blood pressure, oxygen saturations, and neurological status. An arterial line may be required in unstable patients. Blood gases and electrolytes should be checked and corrected as needed. Following initial stabilisation, patients should be transferred to a critical care setting for ongoing monitoring, as recurrence of toxicity can occur. The epidural catheter should be reviewed and usually removed. Documentation and incident reporting are important, along with education to prevent recurrence.

Learning Outcomes

1. Observe the management of LAST in a patient with an epidural infusion.
2. Understand the signs and symptoms of LAST.
3. Understand the key management principles of LAST.

External Resources

• Quick Reference Handbook - Association of Anaesthetists (Local anaesthetic toxicity Section 3-10)