Pediatric dosage calculations

Published

Hi I am going into my second year of nursing which will be pediatrics and maternity. This is the first time I have posted something here although I always read everyone's responses and always find it very helpful so I thought I would give it a try myself. can someone please help me with a couple of dosage calculation problems my professor gave us to prepare for the first day exam? I have asked my professor for the same help but then just told me to read the questions so I am very confused now. below are the problems I could use some explanation on if anyone can help me.

I am still confused on when to round to the tenth place. This two dosage calc questions are similar, yet the answer are rounded differently. Can you please help me understand what I am doing wrong?

3. A physician's order states chloramphenicol 50 mg/kg/day I.V. in divided doses q 6 hours. The child weighs 17 kg.

Each dose would be mg.

3. 50 mg q 6h = 4 doses

x 17 kg

850 = 850 mg/day

850 = 212.5 mg/dose = 213 mg/dose (I left it as 212.5)

4

1. _302.2 mg_ The physician orders Augmentin (amoxicillin and clavulanate potassium)

oral suspension 35 mg/kg/day PO divided in three equal doses.

Patient's weight: 57 lbs

How many milligrams should be administered for one dose?

57 lbs = 25.9 kg 35 mg x 25.9 kg = 906.5 mg/day

906.5 = 302.2 mg/dose

3

On the following question I don't understand why the answer is 0.85mg/kg/day.

5. Yes The physician orders Paveral (codeine sulfate) elixir 3.3 mg po q 6 hrs for pain.

The drug guide recommended dosage is 0.5-1 mg/kg/day

Patient's weight: 34.1 lbs.

Is the physicians order safe?

34.1 lbs = 15.5 kg 3.3 mg x 4 doses = 13.2 mg/day

13.2 mg/day = 0.85 mg/kg/day

15.5 kg

Safe since 0.85 falls within range of 0.5 -1 mg/kg/day

The way I set-up that question is like this:

0.5mg/kg/day X 15.5kg = 7.75mg/day minimum/day

1mg/kg/day X 15.5kg = 15.5mg/day maximum/day

Then I multiply 3.3mg X 4 = 13.2mg/day. Since what the Doctor prescribed is within range I say that this is a safe dose. However my final answer is 13.2mg/day not 0.85mg/kg/day.

Then I proceeded to do the next test and I see the solution is set-up different. Can you please tell me what I am missing?

5. ____yes___ The physician orders Paveral (codeine sulfate) elixir 2.8 mg po q 6 hrs for pain.

The drug guide recommended dosage is 0.5-1 mg/kg/day

Patients weight: 34 lbs.

Is the physicians order safe?

34/2.2= 15.45454545454= 15.5 kg

0.5 x 15.5 = 7.75= 7.8 mg/day is the lower range

1 x 15.5= 15.5 mg/day is the higher range

Safe range is 7.8-15.5 mg/day

MD ordered 2.8 mg q 6 hrs = 2.8 x 4= 11.2 mg/day

11.2 falls in the safe range of 7.8-15.5= dose is safe

Up Vote Up Vote ×
Specializes in MICU.

212.5 should be rounded to 213 because the general rule is that 0.5-0.9 should always be rounded.

All your answers and steps are correct. However the 3rd answer suppose to be 13.2 mg not 0.85mg . The professor/textbook is wrong.

This is how I solved mine:

Doctor's order per day is 3.3mg×4=13.2mg/day

To check whther it is safe is

Lower range: 0.5mg/kg/day×(34.1lb/2.2)=7.75mg/day

Upper range is 1mg/kg/day×(34.1lb/2.2)=15.5

So the safe range is 7.75-15.5

Yes the dosage is safe

Please remove this step from your solution, I think it was a typo: (13.2mg/day ÷15.5kg)=0.85..this answer is irrelevant and the unit doesnt even match

Up Vote Up Vote ×

So if the hundreths place is .5-.9 we round to the tenths? and if the tenths is .5-.9 we round to the whole number?

Up Vote Up Vote ×
Specializes in MICU.

thats correct

Up Vote Up Vote ×

does that rule apply whether it is mg and ml's?

Up Vote Up Vote ×
Specializes in MICU.

rounding is not about mg or ml. it is about rounding to the nearest number whether in hundredth or in tenth. Please don't get it twisted, and another thing is that don't round while solving until you get to your final answer, this would help you get the correct figure or amount

Up Vote Up Vote ×
Specializes in MICU.

i hope that helps

Up Vote Up Vote ×

yes!! that is what I have always done but a few practice problems were not rounded on the weight and the 0.85 answer had me really confused, so thank you so much for clarifying everything for me.

Up Vote Up Vote ×
Specializes in MICU.

you are welcome

Up Vote Up Vote ×
Specializes in Neuro, Telemetry.
thats correct

I hope oped I am just misunderstanding you with your rounding rule advice. What I got from what you said is that when the answer ends in 0.5-0.9 you round to the whole number and when the hundredths place ends in 5-9 ten you round to the tenths. I'm am not quite understanding what you are saying but it doesn't seem correct.

What at place you round to is not dependent on what the ending number is. It is dependent on what place you have been instructed to round to. For IV manual flow rate it is whole numbers. For adult meds it's tenths place. For Pedi it's hundredths place.

Simple rounding:

Whole numbers - 1.0-1.4=1, 1.5-1.9=2

Tenths place - 1.10-1.14=1.1, 1.15-1.19=1.2

hundredths place - 1.110-1.114=1.11, 1.115-1.119=1.12

thats all there is to it.

Unless you are instructed to round to a whole number don't. If your answer is 105.6 unite, don't just go rounding to 106, unless you are told to. Same with tenth and hundredths. Just because you get an answer that is 105.16. Don't just round to 105.2 unless specifically told to round to the tenth place only.

It also seems that your instructor teaches you a little different than mine. For my math tests 212.5 would be correct not 213. And for #1, 302.27 would be the correct answer because it is a Ped calculation and we always round to hundredth on peds (using dimensional analysis) even in basic weight conversions.

Up Vote Up Vote ×
Specializes in MICU.

What at place you round to is not dependent on what the ending number is. It is dependent on what place you have been instructed to round to. For IV manual flow rate it is whole numbers. For adult meds it's tenths place. For Pedi it's hundredths place.

Simple rounding:

Whole numbers - 1.0-1.4=1, 1.5-1.9=2

Tenths place - 1.10-1.14=1.1, 1.15-1.19=1.2

hundredths place - 1.110-1.114=1.11, 1.115-1.119=1.12

thats all there is to it.

that was the instruction given by your instructor...

check this out..

http://www.aultmancollege.edu/Files/Calculations%20and%20Rounding%20Rules.pdf

Up Vote Up Vote ×

ok I understand and yes usually the question will say "round to the tenths" or something like that. I am just going into pediatrics in September and we were never actually taught dosage calculations we were supposed to learn it on our own or take a summer class for it which I didn't because I got 100% on every math quiz but this practice ditto we were given for pediatrics was confusing as to why some were rounded the way they were but I totally get it now with the rounding but does that apply to all medications whether liquid or pills for children?

Up Vote Up Vote ×
+ Add a Comment