Local anaesthetic systemic toxicity
Nov 13, 2025
When Local Turns Systemic: Understanding Local Anaesthetic Systemic Toxicity (LAST)
Local Anaesthetic Systemic Toxicity (LAST) is a rare but potentially life-threatening complication of regional anaesthesia and infiltration techniques. It occurs when plasma concentrations of local anaesthetic become excessive, leading to central nervous system (CNS) and cardiovascular toxicity. 🏥
Although most cases occur during or immediately after the initial injection — often due to inadvertent intravascular administration — LAST can also develop later from accumulation or delayed absorption, particularly with continuous infusions or high total doses.
🔹 Recognising LAST
Early neurological signs:
🔸 Circumoral numbness, metallic taste, tinnitus (early signs)
🔸 Dizziness, agitation, or slurred speech
🔸 May progress to seizures, coma, or respiratory depression (late signs)
Cardiovascular signs:
🔸 Bradycardia, hypotension, arrhythmias
🔸 Severe cases: cardiac arrest, often without preceding CNS symptoms
🔹 Preventive Measures
Perioperative nurses are essential in safe practice through vigilance and teamwork. Key preventive actions include:
🔸 Confirming correct drug, dose, and concentration
🔸 Using incremental injection with frequent aspiration
🔸 Supporting use of ultrasound guidance where appropriate
🔸 Ensuring resuscitation equipment and lipid emulsion (20%) are immediately available
🔸 Observing the patient closely during and after injection — most events occur within minutes
🔹 Immediate Nursing Management
If LAST is suspected:
🔸 Stop local anaesthetic administration immediately (including infusions if running)
🔸 Call for help and initiate standard resuscitation measures
🔸 Maintain oxygenation and ventilation
🔸 Commence 20% lipid emulsion therapy as per ANZCA protocol
🔸 Continue cardiac and vital sign monitoring, documenting all interventions and responses
Simulation training and adherence and review of local LAST management protocols enhance preparedness and outcomes. Early recognition and a rapid, coordinated response save lives. ❤️
Build Knowledge ✅
Improve Safety ✅
References:
Australian and New Zealand College of Anaesthetists. (2014). PS03: Guidelines for the management of major regional analgesia (Professional document). ANZCA. http://hdl.handle.net/11055/21
Barrington, M. J., & Kluger, R. (2013). Ultrasound guidance reduces the risk of local anesthetic systemic toxicity following peripheral nerve blockade. Regional Anesthesia and Pain Medicine, 38(4), 289–299. https://doi.org/10.1097/AAP.0b013e318292669b
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