Pediatric Medication Calculations
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)
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
- Pounds to kilograms
- Safe Dosing
- How to calculate medication dose using ration / proportion
- IV medicaitions
- 24 hour fluid calculations
- Naso-gastric drainage replacement
Slide 7 Slide 8
- 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
- 6.37 pounds divided by 2.2 kg = 2.89 kg
- 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
- 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.
- How to calculate pediatric medication amount per day and per dose:
- Video can be accessed through www.pedstudent.com under medication link
- 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
- 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 mg215 mg
5 ml = x ml
- Give 4.3 mL po every 8 hours
Administration of mL / pediatric
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
- Crucial in the pediatric population
- Units often have policies that children under a certain age are on a fluid control pump.
- 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
- 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
- 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.
Slide 28 Slide 29
- 64 pound child
- Convert pounds to kilograms = 29.09 kg
- 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.
- 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.
- 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.
- 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.
- 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
- Two great articles that explain the concept of “flushing” the line after giving an IV medication
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.
- Child: 5 years: weight 44 lbs
- Order: famotidine (Pepcid) 5 mg IV bid
Slide 41 Slide 42
- 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
- Calculate the dose
- Pepcid is provided as 10 mg/mL
- 10 mg = 5 mg
1 mL x mL
10x 0.5 mL of Pepcid
- Child: 4 years: weight 17 kg
- Physician order: Fortaz (Ceftazidime) 280 mg IV q 8 hours
Drug Guide Information
- 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
Safe dose is 30 to 50 mg/kg/day
Drawing up the medication:
1 gram / 10 mL or 95 mg / 1 mL
95 mg = 280 mg280
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
- The drug guide states that the drug can be safely administer over 30 minutes.
- 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?
- 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.
- 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.
- 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.