Pediatric Medication Calculations UNRS 314 Jan Bazner-Chandler CPNP, CNS, MSN, RN.

Pediatric Medication Calculations

UNRS 314

Jan Bazner-Chandler

CPNP, CNS, MSN, RN

Conversions you need to remember 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 If an infant consumes 3 ½ ounces of formula

how many mL was consumed?

grains (gr) to milligrams (mg) gr 1 = 60 mg gr ¾ = 45 mg gr ½ = 30 mg gr ¼ = 15 mg

Calculations

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

Pounds to kilograms = pounds

2.22.2

Nursing Alert:Nursing Alert:

In pediatrics you need to carry out to the In pediatrics you need to carry out to the hundredths (hundredths (do not rounddo not round))

Kilogram Example

20 pounds 5 ounces First need to convert 5 ounces to a fraction of

a pound 5 divided by 16 = 0.31

20.31 pounds divided by 2.2 = 9.23 kilograms

Note medication would be calculated based on 9.23 kilograms. DO NOT ROUND

Calculations of pounds to kilograms If a child weighs 84 lbs, what is the weight in

kg? 84lb = ____ kg 84 divided by 2.2 = 39.18 kg

Pounds to kilograms

If a child weights 6 lbs 6 ounces what is the weight in kg?

6 ounces = 0.37 pounds

16 ounces

6.37 pounds divided by 2.2 kg = 2.89 kg

Calculations

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

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 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

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

How to calculate pediatric medication amount per day and per dose:

http://www.youtube.com/watch?v=PFDxR5RtnYQ

Video can be accessed through www.pedstudent.com under medication link

Calculation

A child is 2 years and weighs 36 lbs Physician order: Amoxicillin 215 mg po tid for a

bilateral otitis media (ear infection)

First you would need to change 36 lbs to kg

36 divided by 2.2

Patient weight in kg = 16.36 kg

Calculating Safe Range

Davis drug guide: PO (children) < 40 kg: Amoxacillin 6.7 to 13.3 mg / kg q 8 hours.

(low range)16.36 x 6.7 = 109.6 mg q 8hours

(high range)16.36 x 13.3 = 217.5 mg q 8 hours

Safe Range

109.6 mg to 217.5 mg of Amoxicillin Q 8 hours.

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

250 mg 215 mg

5 ml = x ml 1075

250x Give 4.3 mL po every 8 hours

Administration of mL / pediatric mL can be administered up to the tenths

PO medication via oral syringe

http://www.youtube.com/watch?v=dTj5_y_VuMg

Safe Dose Ranges

Read the medication ranges carefully: dosing can be for:

dose range for 24 hours

dose range for q 8 hours

dose range for q 12 hours

Fluid Control

Crucial in the pediatric population Units often have policies that children under

a certain age are on a fluid control pump.

Key concepts

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

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

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

The maintenance dose for administration of IV fluids is based on the following formula

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

You need to memorize this

Practice problem

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

7.27 kilograms

100 mL x 7.27 kg = 727 mL

727 mL / 24 hours or 30 mL per hour

Fluid Calculation

64 pound child Convert pounds to kilograms = 29.09 kg Fluid calculations:

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

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

Child number #1 maintenance fluid needs are 713 mL / 24 hours.

1 ½ time maintenance would be 713 x 1.5 = 1069 mL / 24 hours or 45 mL / hour.

Fluid Calculation

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

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

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

http://www.youtube.com/watch?v=clh6kPXhOlE

Parenteral Pediatric Medications 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

Child: 5 years: weight 44 lbs Order: famotidine (Pepcid) 5 mg IV bid

Drug Guide Information

Usual Dosage:

0.5 mg / kg / day divided twice daily (maximum 40 mg / day)

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

Convert pounds to kg: 44 lb = 20 kg Determine safe dose:

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

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

Child: 4 years: weight 17 kg Physician order: Fortaz (Ceftazidime) 280 mg

IV q 8 hours

Drug Guide Information

Dosing: 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/daySafe 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 280

1 mL x mL 95x = 2.94 mL or 2.9 mL

DO NOT ROUND UP TO 3 mL

Example # 2

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?

THE PHYSICIAN ORDER WILL NEVER STATE TO FLUSH THE LINE – YOU MUST DO THIS WITH EACH IV MEDICATION

Example #2

The drug guide states that the drug can be safely administer over 30 minutes.

Formula: 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

If a child has a nasogastric tube that is draining fluid the physician will often write and order for: NG drainage – cc/cc replacement q 4 hours

What does this mean?

Nasogastric Output

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

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

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.