Last Updated on by
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:
Leave A Comment?