Rounding rules

[Nina96]

I start my pediatric rotation next semester in a pediatrician office. I just want to know how to round my drug calculations for these patients I looked up some examples and wanted to know if I'm right. Physician orders Tylenol 15 mg per kg per dose for 1 year old that weighs 21lbs amount on hand is 160mg/5ml how many ml would you administer per dose? My answer comes out to 4.474 ml. Is this amount rounded to the tenths or hundredths place? Also another question a a 35 lb child is ordered rocephin 50mg per kg IM divided in 2 doses amount available is 350 per ml? I come up with 2.27 ml divided by 2 which come out to be 1.136 ml which I rounded to 1.1ml.

[KelRN215, BSN, RN]

Your math is correct. You cannot measure 4.47 mL accurately so you round to 4.5 mL. For the IM, again, your math is correct and you cannot accurately measure 1.136 mL so rounding to 1.1 mL is correct. Usually 1 mL is the maximum volume administered IM in this age group.

In reality, at least anywhere I've ever worked, orders written as 15 mg/kg or 50 mg/kg with the child's weight measured in pounds would be rejected by the pharmacy. The ordering provider needs to do the math and order Tylenol 143 mg (which he or she would probably just order 140 mg) or Rocephin 795 mg IM. We check the math to make sure the dose is correct, as does the Pharmacist, but the order isn't valid unless the dose to administer is actually specified in it.

Also, it's always important to check the policies and procedures of the facility in which you're doing your rotation. You will have a clinical instructor to guide you.