Local Anaesthetic Toxicity

Last Updated on by FRCEM Intermediate

Overview

  • sodium channel blockade -> arrhythmias and neurotoxicity

Prevention

  • know your maximum doses
  • aspiration before injecting avoid injecting intravenous or intra-arterial
    small, divided doses
  • inject slowly & ask about symptoms
  • Higher doses can be used is co-administered with adrenaline to reduce systemic absorption of LA
  • increased LA effect in – acidosis, hypoxia, hypercarbia

Clinical Features

Early: Tinnitus, dizziness, anxiety, confusion and perioral numbness
Severe CNS: Seizures, coma
Severe Cardiovascular: bradycardia, hypotension, atrial and ventricular dysrhythmias, cardiovascular collapse and asystole.

Management

  • Stop injecting or infusion
  • Call for help
  • Give 1-1.5 ml/kg IV Lipid emulsion 20% as an IV bolus over 1 minute

 

Onset (min) Duration (min) Max dose (mg/kg) Max mg (70kg person)
Lignocaine (1% or 2%)
(Xylocaine)
2 15-60 3mg/kg 220mg
(11mL 2%)
(22mL 1%)
Lignocaine with adrenaline
(1% or 2%)
2 120-360 7mg/kg 500mg
(25mL 2%)
(50mL 1%)
Bupivicaine (0.25%)
(Marcain)
5 120-240 2.5mg/kg 175mg(50mL)
Bupivicaine with adrenaline 5 180-420 3mg/kg 225mg
Prilocaine (0.5% or 1%)
(Citanest)
2 30-90 7mg/kg 500mg (<70kg)(50mL 1%)
Ropivocaine (0.25%)
(Naropin)
5 120-360 3mg/kg 225mg
Mepivocaine (1%)
(Polocaine)
3-5 45-90 4mg/kg 280mg
(28mL 1%)
Mepivocaine (1%)
With adrenaline
120-360 7mg/kg 400mg




Calculating the maximum dose of local anaesthetic agent

  • Maximum dose of lignocaine without adrenaline is 3 mg/kg.
  • Maximum dose of lignocaine with adrenaline is 7 mg/kg.
  • Lignocaine concentration in solution:
    • 0.25% =  0.25 g/100mL or 2.5mg/mL
    • 0.5%  = 0.5 g/100mL or 5mg/mL
    • 1%     = 1 g/100mL or 10mg/mL
    • 2%     = 2 g/100mL or 20mg/mL
  • Thus, in a 70-kg patient do not use more than:
    • 20 mL 1% plain lignocaine or 10 mL 2% plain lignocaine
    • 48 mL 1% lignocaine with adrenaline or 24 mL 2% lignocaine with adrenaline

Read:

Local Anaesthetic Toxicity

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