LAST is a life-threatening complication resulting from high plasma concentrations of local anaesthetic (LA). It most commonly occurs due to accidental intravascular injection or rapid systemic absorption.
Clinical Presentation
| System | Early Signs | Late/Severe Signs |
|---|---|---|
| CNS | Circumoral numbness, metallic taste, tinnitus, and dizziness. | Seizures, coma, respiratory arrest. |
| Cardiovascular | Tachycardia, hypertension (initial). | Bradycardia, hypotension, heart block, VF/Asystole. |
Management & Prevention
- Immediate Action: STOP injection, call for help, manage airway (100%
), and control seizures (benzodiazepines).
- Specific Antidote: Lipid Emulsion Therapy (Intralipid) is the definitive treatment. It acts as a “lipid sink” to sequester the highly lipophilic LA molecules from systemic circulation.
- Prevention: Use ultrasound guidance, aspirate frequently before injection, and use the lowest effective dose.
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