You are treating a 60kg patient for a laceration, which you will need to suture under local anaesthetic. Given that the maximum safe dose of lignocaine is 3mg/kg, what is the maximum volume of a lignocaine 1% weight per volume (w/v) solution that can be administered safely?
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mL = milli litres ; µL = micro litres
1 litre = 1000 mL = 1 kg = 1000 g
1% weight per volume (w/v) solution means
1 litre has 0.01 kg of lignocaine
Or 1000 mL = 10 g = 10,000 mg
3mg/kg X 60 kg X 1000mL/10000 mg =18 mL
The correct answer is D.