 Pediatric Medication Calculations

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

Review 1 teaspoon = 5 mL / cc 1 tablespoon = 15 mL / cc
1 ounce = 30 mL /cc Remember the clock! grains to grams to milligrams. How to calculate medication dose using ration / proportion. 16 oz = 1 pound (body weight)

IV Fluid Calculation Adult (Review)
Step # 1 Total number of milliliters ordered = ml / hr number of hours to run Step # 2 Milliliters per hour x tubing drip factor = gtt/min Minutes

Pounds to Kilograms Pounds to kilograms = pounds 2.2
In pediatrics you need to carry out to the hundredths (do not round especially in the infant or small child)

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 Notes medication would be calculated based on 9.23 kilograms. DO NOT ROUND to 9.2

New Calculations Mg / kg dosing based on weight (kg)
Safe dosing ranges IV pediatric infusion rates IV administration of meds per volutrol or syringe pump. 24 hour fluid calculation

Calculations of pounds to kilograms
If a child weighs 84 lbs, what is the weight in kg? 84lb : x kg 84 divided by 2.2 = kg 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 2.89 = kg

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 the safe range to see if it falls within the safe zone.

Calculation A child is 2 years and weighs 36 lbs is receiving Amoxicillin 215 mg po tid for a bilateral otitis media (ear infection). Patient weight in kg = kg Davis drug guide: PO (children) < 40 kg: 6.7 to 13.3 mg / kg q 8 hours. (low range)16.36 x 6.7 = mg q 8hours (high range)16.36 x 13.3 = mg q 8 hours Safe range: to mg of Amoxicillin Q 8 hours. Is the dose safe? Yes, it falls within the safe range.

How much medication do you give?
Physician order Amoxicillin 215 mg every 8 hours. Suspension comes 250 mg per 5 ml. 250 mg 215 mg 5 ml = x ml 1075 250x Give 4.3 mL / cc po every 8 hours

Safe Dose Ranges Read the medication ranges carefully
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 mls 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 mL per hour

Fluid Calculation 64 pound child
Convert pounds to kilograms = kg Fluid calculations: 100 mL x 10 kg = 1000 mL 50 ml x 10 kg = mL 20 ml x 9.09 kg = 181 mL 1681 mL / 24 hours or 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 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 ½ = 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 ½ = 2522 mL / 24 hours or 105 mL / hour.

IV bolus A 6 year old with dehydration is admitted to your unit. The referring hospital has an adult IV set-up. (drip factor of 15 gtt/ml) The physician order is to infuse 90 mL of normal saline over 1 hour. At what rate will you set the IV rate? (90 ml x 15 gtts) divided by 60 minutes Hourly rate would be 23 gtts/minute

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.

Syringe Pump

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: 0.25 mg / kg q 12 hr IV up to 40 mg/day.

Example #1 Convert pounds to kg: 44 lb = 20 kg Determine safe dose:
20 kg x 0.25 mg = 5 mg 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 mL of Pepcid

Example #1 Drug guide: dilute with 5 or 10 mL and infuse over 2 minutes. The medication would be injected directly into the tubing of actively running IV; inject slowly over 1 to 2 minutes.

Example #2 Child: 4 years: weight 17 kg
Physician order: Fortaz (Ceftazidime) 280 mg IV q 8 hours Drug guide: Safe dose 30 to 50 mg/kg/day 50 mg/mL over 30 minutes Drug supplied as 1 gram powder. Directions: Dilute with 10 mL of sterile water to equal 95 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 x = 2.94 mL

Example # 2 Adding medication to the volutrol
Take the 2.94 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 In and infant or child has a nasogastric tube in that is draining fluid the physician will often write and order for: NG drainage – cc/cc replacement 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 cc’s 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. You IV would be set at 115 mL + 37 mL = 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 80% or better to be able to safely administer medications in the clinical setting.

NG Fluid Replacement Order to replace NG suction loss
Often written by MD to read Replace cc / cc NG output every 4 hours

Practice Problem At 0700 report the NG output for the last 4 hours is 120 mL. Divide 120 mL by 4 (hours) = 30 mL Add the 30 mL to the hourly IV rate Example: IV rate is 120 mL per hour 120 mL + 30 mL = 150 mL Run the IV at 150 mL over the next 4 hours