Local anaesthetic systemic toxicity

complications local anaesthetic nerve blocks regionalanaesthesia 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

Stay connected with news and updates!

Join our mailing list to receive the latest news and updates from our team.
Don't worry, your information will not be shared.

We hate SPAM. We will never sell your information, for any reason.

Want to keep learning?

Want more content like this? Check out our premium membership for exclusive content. 

Click Here for Access

 

 

Join our mailing list for free weekly educational content.

 

By entering your details you consent to receiving amazing educational materials and updates about our products and events.