Pediatric Medication
Calculations
UNRS 314
Jan Bazner-Chandler
CPNP, CNS, MSN, RN
Conversions you need to remember
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1 teaspoon = 5 mL / cc
1 tablespoon = 15 mL / cc
1 ounce = 30 mL /cc
1 gram (g) = 1000 milligrams (mg)
1 milligram (mg) = 1000 micrograms (mcg)
1 liter (L) = 1000 milliliters (mL)
Measuring cup
How many mL in 4
teaspoons?
Intake and Output charted in mL
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If an infant consumes 3 ½ ounces of formula
how many mL was consumed?
grains (gr) to milligrams (mg)
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gr 1 = 60 mg
gr ¾ = 45 mg
gr ½ = 30 mg
gr ¼ = 15 mg
Calculations
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Pounds to kilograms
Safe Dosing
How to calculate medication dose using
ration / proportion
IV medicaitions
24 hour fluid calculations
Naso-gastric drainage replacement
Pounds to Kilograms
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Pounds to kilograms = pounds
2.2
Nursing Alert:
In pediatrics you need to carry out to the
hundredths (do not round)
Kilogram Example
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20 pounds 5 ounces
First need to convert 5 ounces to a fraction of
a pound 5 divided by 16 = 0.31
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20.31 pounds divided by 2.2 = 9.23 kilograms
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Note medication would be calculated based
on 9.23 kilograms. DO NOT ROUND
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Calculations of pounds to kilograms
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If a child weighs 84 lbs, what is the weight in
kg?
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84lb = ____ kg
84 divided by 2.2 = 39.18 kg
Pounds to kilograms
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If a child weights 6 lbs 6 ounces what is the
weight in kg?
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6 ounces = 0.37 pounds
16 ounces
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6.37 pounds divided by 2.2 kg = 2.89 kg
Calculations
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mg / kg dosing based on weight
Safe dosing ranges
IV pediatric infusion rates
IV administration of meds per volutrol or
syringe pump.
24 hour fluid calculation
Nasogastric fluid replacement
Medication dosage
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For a dosage of medication to be safe, it
must fall within the safe range as listed in a
Drug Handbook, PDR or other reliable drug
reference.
Dosage based on mg/kg and Body Surface
Area
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The dose of most pediatrics drugs is based
on mg/kg body weight or Body Surface Area
(BSA) in meters squared.
For testing purposed mg / kg will be used.
BSA method of calculations may be seen in
NICU, ICU and high acuity areas.
Safe Medication Dose
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Calculate daily dose ordered (Physician
orders)
Calculate the low and high parameters of
safe range (from drug book)
Compare the patient’s daily dose to see if it
falls within the safe range.
Dosing
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How to calculate pediatric medication amount
per day and per dose:
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http://www.youtube.com/watch?v=PFDxR5Rt
nYQ
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Video can be accessed through
www.pedstudent.com under medication link
Calculation
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A child is 2 years and weighs 36 lbs
Physician order: Amoxicillin 215 mg po tid for a
bilateral otitis media (ear infection)
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First you would need to change 36 lbs to kg
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36 divided by 2.2
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Patient weight in kg = 16.36 kg
Calculating Safe Range
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Davis drug guide: PO (children) < 40 kg:
Amoxacillin 6.7 to 13.3 mg / kg q 8 hours.
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(low range)16.36 x 6.7 = 109.6 mg q 8hours
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(high range)16.36 x 13.3 = 217.5 mg q 8 hours
Safe Range
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109.6 mg to 217.5 mg of Amoxicillin Q 8
hours.
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Is the 215 mg dose ordered by the MD
safe? Yes (it falls within the safe range)
How much medication do you give?
Amoxicillin Suspension comes:
250 mg per 5 mL you want to give 215
mg
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250 mg 215 mg
5 ml = x ml
1075
250x
Give 4.3 mL po every 8 hours
Administration of mL / pediatric
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mL can be administered up to the tenths
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PO medication via oral syringe
http://www.youtube.com/watch?v=dTj5_y_VuMg
Safe Dose Ranges
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Read the medication ranges carefully: dosing
can be for:
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dose range for 24 hours
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dose range for q 8 hours
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dose range for q 12 hours
Fluid Control
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Crucial in the pediatric population
Units often have policies that children under a
certain age are on a fluid control pump.
Key concepts
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Fluid overload must be avoided
Time over which a medication should be
administered is critical information
Minimal dilution (end concentration of
medication) is important for medications such
as aminoglycosides.
Collecting therapeutic blood levels
Fluid overload
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Know what the IV rate is.
Hourly recording of IV fluid intake.
Don’t try and catch up on fluids.
Calculate fluids used to administer IV
medications into the hourly fluid calculations.
Daily Fluid Needs
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Fluid needs should be calculated on every
patient to assure that the infant / child is
receiving the correct amount of fluids.
Standard formula for pediatrics needs to be
memorized.
IV fluid calculations
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The maintenance dose for administration of
IV fluids is based on the following formula
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100 mL of fluid for the 1st 10 kg of weight
50 mL of fluid for the 2nd 10 kg of weight
20 mL of fluid for and additional kg
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You need to memorize this
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Practice problem
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Jose weighs 16 pounds
Weight in kg = 7.27 kg
Using the formula provided how many ml of
fluid would he need in 24 hours.
Fluid Calculation
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7.27 kilograms
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100 mL x 7.27 kg = 727 mL
727 mL / 24 hours or 30
mL per hour
Fluid Calculation
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64 pound child
Convert pounds to kilograms = 29.09 kg
Fluid calculations:
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100 mL x 10 kg = 1000 mL
50 ml x 10 kg = 500 mL
20 ml x 9.09 kg = 181 mL
1681 mL / 24 hours or 70
mL / hour
Fluid Calculations
Fluid calculations can be rounded. You cannot
administer a fraction of a mL.
•
In child #1 the calculated hourly rate of 29.7
would be rounded to 30 mL / hour.
•
In child #2 the calculated hourly rate of 70.04
would be rounded to 70 mL / hour.
Fluid Calculations
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Since children are in the hospital for various
illnesses they will often have increased fluid
needs: dehydration, fever, vomiting, diarrhea,
inability to take po fluids.
24 hour fluid calculations may be 1 ½ to 2
times maintenance.
Fluid Calculations
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Child number #1 maintenance fluid needs are
713 mL / 24 hours.
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1 ½ time maintenance would be 713 x 1.5 =
1069 mL / 24 hours or 45 mL / hour.
Fluid Calculation
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In child # 2 maintenance fluid needs are 1681
mL / 24 hours.
1 ½ times maintenance would be 1681 x 1.5
= 2522 mL / 24 hours or 105 mL / hour.
IV Buretrol
IV Buretrol
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A buretrol or volutrol is an inline receptacle
between the client’s IV catheter set and the
bag of fluids.
Capacity is 120 to 150 mL
Rationale: the nurse can fill the buretrol to a
certain level and if the IV pump malfunctions,
only the volume in the buretrol will flow to the
client.
Flushing buretrols / solusets
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http://www.iv-therapy.net/node/1319
Two great articles that explain the concept of
“flushing” the line after giving an IV
medication
Syringe Pump
Syringe pumps
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http://www.youtube.com/watch?v=clh6kPXhO
lE
Parenteral Pediatric Medications
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Step 1: Convert lb to kg
Step 2: Determine the safe range in mg/kg
Step 3: Decide whether the dose is safe by
comparing the order with safe dose range
Step 4. Calculate the dose needed
Step 5. Check reference for diluent and
duration for administration.
Example #1
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Child: 5 years: weight 44 lbs
Order: famotidine (Pepcid) 5 mg IV bid
Drug Guide Information
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Usual Dosage:
0.5 mg / kg / day divided twice daily
(maximum 40 mg / day)
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Administration: May be administered IV push
over a period not less than 2 minutes or as
an intermittent infusion over 15 to 30 minutes;
final concentration not to exceed 4 mg/mL.
Example #1
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Convert pounds to kg: 44 lb = 20 kg
Determine safe dose:
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20 kg x 0.5 mg = 100 mg
100 mg divided by 2 (drug is given twice a day)
5 mg is safe it meets mg / kg rule and does not
exceed 40 mg/day.
5 mg bid = total of 10 mg/day
Example #1
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Calculate the dose
Pepcid is provided as 10 mg/mL
10 mg = 5 mg
1 mL x mL
5 =
10x
0.5 mL of Pepcid
Example #2
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Child: 4 years: weight 17 kg
Physician order: Fortaz (Ceftazidime) 280 mg
IV q 8 hours
Drug Guide Information
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Dosing:
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Safe dose 30 to 50 mg/kg/day
Drug supplied as 1 gram powder. Directions:
Dilute with 10 mL of sterile water to equal 95
mg/mL.
Administration: intravenous infusion over 15
to 30 minutes; may be given IV over 3-5
minutes at final concentration of 100 mg/mL
Example #2
Safe dose is 30 to 50 mg/kg/day
• Low range: 17 kg x 30 mg = 510 mg/day
• High range: 17 kg x 50 mg = 859 mg/day
Safe range is 510 to 859 mg/day or 170 to 286
per dose.
If the order is to give the drug q 8 hours you
would need to divide the safe range by 3 or
multiple the q 8 hour dose x 3.
Example #2
Drawing up the medication:
1 gram / 10 mL or 95 mg / 1 mL
95 mg = 280 mg
1 mL
x mL
mL
280
95x = 2.94 mL or 2.9
DO NOT ROUND UP TO 3 mL
Example # 2
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Adding medication to the volutrol
Take the 2.9 mL of Ceftazidine – inject it into
the port on the volutrol and add additional IV
fluid to = 10 mL.
Example # 2
The flush: evidence based practice has
demonstrated that in an effort to get the IV
medication from the volutrol to the patient the
line needs to be flushed with 20 mL of IV fluid
after the medication is into the IV line.
What about the flush?
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THE PHYSICIAN ORDER WILL NEVER
STATE TO FLUSH THE LINE – YOU MUST
DO THIS WITH EACH IV MEDICATION
Example #2
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The drug guide states that the drug can be
safely administer over 30 minutes.
Formula:
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10 mL (medication) + 20 mL flush following the
medication = 30 mL of fluid that needs to infuse
over 30 minutes.
The pump would need to be set at 60 mL for the
medication + the flush to be infused over ½ hour.
NG – cc/cc replacement
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If a child has a nasogastric tube that is
draining fluid the physician will often write
and order for:
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NG drainage – cc/cc replacement q 4 hours
What does this mean?
Nasogastric Output
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NG output is measures q 4 hours.
At the beginning of the shift the night nurse
reports that the drainage was 150 mL for the
last 4 hours and you need to replace this over
the next four hours.
Note: this is in addition to the IV hourly rate
ordered.
Sample problem
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IV hourly rate is 115 mL/hour
NG output to be replaced over the next 4
hours is 150 cc’s or 37 mL/hour.
IV would be set at 115 mL + 37 mL = You
would run the IV at 152 mL / hour for the next
four hours.
Practice Problems
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Do the practice problems.
Can be done individually or in groups.
Testing will be on like problems.
You must achieve 90% or better to be able to
safely administer medications in the clinical
setting.