HPAT Practice Question Section 1

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?

A. 180µL

B. 6mL

C. 1.8mL

D. 18mL



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Solution:

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

Therefore,

3mg/kg X 60 kg X 1000mL/10000 mg =18 mL

The correct answer is D.