# LA and epi

Discussion in 'NBDE Exams & Licensure Exams' started by dyana, Jun 22, 2008.

1. ### dyana 2+ Year Member

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a 40 lbs child requires multiple surgeries under LA. the max # of cartidges of lidocaine with 1:100000 epi that may be safely add at one time is....
plz explain how to attempt these qns.....
thanks...

2. ### docsmiley newbie 2+ Year Member

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one way is to use clarks rule...divide the healthy adult dose by 1/3.and that gives the child dose..
for 2% lignocaine with epinephrine, in a 2.2 ml cartridge, the upper adult dose is 4 and a half cartridges...
so the child safe dose would be one and a half cartridges..
is there any other simpler method to calculate this ??
if any one knows of it..do reply..

3. ### ItsGavinC DentistModerator Emeritus 15+ Year Member

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A child should not receive more than 4.4 mg/kg or 2.0 mg/lb of anesthesia.

A 40lb child could therefore receive 80 mg of local.

2% Lidocaine has 34-36 mg of local in it (some carps have 1.7ml others have 1.8ml but it doesn't really matter).

80/36 = a little more than 2. So a 40lb child can have 2 carpules of 2% Lido.

4. ### ItsGavinC DentistModerator Emeritus 15+ Year Member

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By the way, that is the dumbest "rule" I've ever heard in my life--no offense directed at you. We shouldn't divide ANY adult dose by 1/3 for a child. A child isn't simply 1/3 an adult. That's a great way to kill a child, as has been demonstrated by many dentists and physicians, unfortunately.

Weight (or body surface area which is even better!) should ALWAYS be used when calculating pediatric drug dosages.

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