NCLC Program
NURS 128
MATERNAL CHILD NURSING
DOSAGE
CALCULATION MODULE
Complete prior to first Peds Clinical session. There will be a
dosage calculation assessment on the first day of Peds
clinical.
PN 2023/2024
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PEDIATRIC DOSAGE CALCULATION MODULE
PURPOSE
The purpose of this module is to assist the student nurse to adapt previously learned
knowledge and skills related to dosage calculations to the calculation of medications for
infants and children. Upon completion of this unit, the student will demonstrate competency
in calculating:
A.
safe dose for a child based on weight
B.
fractional doses from a larger dose
ASSUMPTIONS
It is expected that the student nurse will possess the knowledge and skills required in
previous nursing courses regarding the administration of medications and the
calculation of fractional doses from larger doses for infants and children.
RATIONALE
Nurses must have an understanding of the safe dosage of medications that they administer
to infants and children, as well as knowledge of the expected action, possible side effects,
and signs of toxicity. Unlike adult medications, there is no standardized dosage ranges for
infants and children. Instead, there is information regarding safe dosage ranges based on
weight and/or age. Therefore, it is the responsibility of the nurse to ensure that the ordered
dose is safe for the pediatric patient. Adult doses are often based on an average weight of
150 pounds. Drugs are often prepared and packaged in average adult-dosage strengths.
Therefore, the ability to calculate fractional doses from larger doses is essential.
USE OF THE MODULE
Students are responsible for being knowledgeable in the content of this module. Students are
expected to be self-directed in completing this module and to seek assistance from faculty as
needed.
EVALUATION
The student will be expected to achieve 100% on at least 1 dosage calculation test. If the
student does not successfully complete the first test attempt with 100%, it is strongly
suggested that the student review and remediate in the lab the information that presented
difficulty before retesting. If the student does not successfully complete the second attempt,
the student must review and remediate in the lab before the third attempt. All attempts
must be completed by the scheduled due date and time.
The student will have a maximum number of three attempts to pass the exam. Failure to
pass the exam in three attempts will result in the student receiving an unsatisfactory grade
in clinical. The first exam will be given during scheduled lecture time. If required, the second
and third test location TBA.
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STUDENTS WILL BE PROVIDED WITH A CALCULATOR FOR ALL MEDICATION EXAMS.
In the clinical setting, the student will use their own calculator. Students will not
be able to use their own PDAs or cell phones for these exams and test questions.
There will also be drug/dosage calculation problems on all three of the exams in
NURS 128 and NURS 248. Students will be provided with a calculator for those
problems.
UNIT I
Learning Activities
*Review Pediatric Maintenance Fluid Calculation on page 1276 Table 35.4*
Calculation of Drug Dosages
1.
Read and complete activities associated with SAFE DOSAGE CALCULATION FOR
CHILDREN, contained in this module.
2.
Complete the practice problems for Unit I, in this module.
3.
Review answers to practice problems for Unit I can be found on page 11.
4.
Review “Medication Administration” content in your textbook, chapter 35.
UNIT I • There are six steps the nurse must take to ensure that the dose given to the child is
safe. If the medication is an IV infusion, a seventh step will be necessary.
STEP 1: FIND THE SAFE DOSAGE GUIDELINES FOR THE MEDICATION ORDERED.
Dosage guidelines for medications given to children may be found in a variety of sources. In
the clinical setting a variety of references are available to determine safe dosage guidelines.
Your clinical instructor will direct you to the references you are to use. For the purposes of
this module and for all dosage calculation exams and test questions, the student
will be provided with the safe dosage guidelines.
The safe dosage guideline provides the nurse with three important pieces of information.
a.
It tells the nurse the safe, maximum quantity of medication per weight (in
kilograms) that the child may have.
b.
It identifies the time span over which the safe maximum quantity can be
administered.
c.
It also specifies the safe dosage range considering the route ordered.
Example: The safe dose for Morphine is 0.1 – 0.2 mg/kg/dose. If a range is given for
the safe dose (as in this example) the nurse should always use the larger value for
the calculations. For example: if a child weighs 10 kg, he can receive 1- 2 mg of
Morphine q 3-4 hours (0.1mg x 10kg = 1.0mg, 0.2mg x 10kg = 2mg)
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Example: The safe dosage range for Gentamycin is a maximum of 5-7 mg/kg/24 hours.
This means that the most a child can safely receive is 7 mg of Gentamycin per kg
of body weight. For example: if the child weighs 3.4 kg, he can receive a
maximum of 7 mg/24 hours x 3.4kg = 23.8 mg of Gentamycin. This is the
maximum dose that the child can receive in a 24 hour time period. If the order for
Gentamycin is q 8 hours, the three doses added together cannot exceed 23.8 mg.
(PLEASE NOTE THAT THE NUMBER “23.8” IS NOT ROUNDED OFF TO 24
MG!)
STEP 2: FIND THE CHILD'S MOST RECENT WEIGHT AND CONVERT IT TO KILOGRAMS.
The child's most recent weight should be obtained in order to calculate whether or not a
particular medication is safe. Over a period of time particularly if they are ill, a child may lose
or gain a significant amount of weight (especially during hospitalization) which could alter the
safeness of a prescribed drug.
Most safe doses of medications are stated per kilogram. If the child has been weighed in
pounds, the weight must be converted to kilograms. (Although in the clinical setting, the
policy is to weigh all patients in kilograms). To convert pounds to kilograms, divide the
pounds by 2.2 (There are 2.2 pounds in each kilogram).
Example: How many kg does 66 lb Laura weigh?
30 kg
2.2 kg 66 lb
(A good “rule of thumb” to use if you want to verify that you have done this step correctly is
to remember that if you have done the conversion correctly your weight in kilograms will be
a smaller number than the weight was in pounds and ounces)
STEP 3: CALCULATE THE MAXIMUM SAFE DOSAGE OF MEDICATION FOR THE CHILD'S
WEIGHT.
In order to calculate the maximum safe dose, multiply the child's weight (in kilograms) by
the amount of the drug recommended per kg over a 24 hour period or per dose
Example: Bobby weighs 14 lbs.
The order reads Ampicillin 250 mg IV q 4 hours.
Step 1:
Determine safe dose guideline.
The safe dose of Ampicillin in mild-moderate infections is 50-100 mg/kg/day, IM
or IV.
Step 2:
Convert weight to kg.
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6.3636 kg
2.2 kg
14 lb
Note: It is impractical to deal with a number with as many digits as 6.3636 so it is
necessary to round this off. The accepted "rule of thumb" is to round off to 2
places past the decimal point. In order to do this, look at the following
information: If the 3rd number past the decimal point is 5 or greater, round the
second number past the decimal point up; if it is less than 5, the second number
past the decimal point stays the same. In this example, the 3rd number past the
decimal point is a 3, therefore you would leave the second number past the
decimal point the same, making the weight 6.36 kg
Step 3:
Calculate the maximum safe dose.
100 mg/kg/24 hours
× 6.36 kgs
ANSWER: 636 mg/24 hours is the maximum safe dose that the child can receive.
STEP 4: COMPARE THE AMOUNT OF MEDICATION THAT THE PHYSICIAN HAS ORDERED FOR
24 HOURS OR PER DOSE WITH THE MAXIMUM SAFE DOSE CALCULATED IN STEP 3.
Most of the time, the safe dose guidelines will specify "per 24 hour". When this is the case,
the nurse must calculate the amount of medication the child is to receive in a 24 hour time
period and then compare it with the maximum safe dose. For example, if a medication is
ordered q 4 hours, then there would be 6 doses given in 24 hours. The nurse must multiply
the amount of medication ordered by the number of times it is given in a 24 hour time
period.
Example: Bobby's Ampicillin is ordered 250 mg IV q 4 hours. Infuse over 15 minutes.
How much Ampicillin will Bobby receive in 24 hours?
a.
Calculate number of doses per 24 hours:
24 hours/Q 4 hours = 6 doses/24 hours
b.
Multiply the amount of each dose ordered by the frequency ordered.
250 mg/dose
×6 doses in 24 hours
ANSWER: 1500 mg is the maximum amount of the medication that the child
can receive in a 24 hour time period
In some instances, safe dosage guidelines will specify per dose. These are usually
your PRN medications.
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Example: Maria weighs 7 lbs. The order reads:
Morphine 0.5 mg IV Q 2 – 4 hours PRN.
Step 1:
Determine safe dose guideline. Morphine may be given 0.1 – 0.2
mg/kg/ dose q 2-4 hours.
Step 2:
Convert weight to kilograms.
3.18 kg
2.2 kg
7 lbs
Step 3:
Calculate the maximum safe dose.
Step 4:
In this instance, the nurse need only compare the amount ordered
(0.5mg/dose) with her calculations from Step 3.
STEP 5: DECIDE IF THE AMOUNT OF MEDICATION ORDERED FALLS WITHIN THE MAXIMUM
SAFE DOSAGE PARAMETERS.
If the amount of medication ordered is less than the maximum safe dose, it may be
determined to be safe for that particular child and the nurse may administer the medication
as ordered. In other words, if step 4 is less than step 3, the dose is safe.
If the amount of medication ordered is more than the maximum safe dose, it may be
determined to be unsafe for that particular child and the nurse may not administer the
medication as ordered. Or, in other words, if step 4 is more than step 3, the dose is unsafe.
The nurse would consult with the physician who wrote the medication order to determine the
appropriate course of action for this medication order.
Example: Bobby is to receive Ampicillin 1500 mg in 24 hours. The maximum safe dose
calculated previously was 636 mg/24 hours. Is the ordered dose safe?
No, it is not. (1500 mg is more than 636 mg)
STEP 6: CALCULATE THE AMOUNT OF MEDICATION TO BE GIVEN PER DOSE:
The nurse is to utilize previously learned methods for calculating the amount of medication to
be given.
Dose Ordered
--------------- X How it is supplied (mL, tab,etc)
Dose on Hand
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Supplied: Ampicillin 100mg/mL
250 mg
_______
100 mg
X 1mL =
2.5mL
STEP 7: If the medication to be given is an IV infusion: CALCULATE HOW FAST THE
MEDICATION WILL BE INFUSED. Pediatric IV calculations will always use microdrip tubing
(60gtts/mL)
Infuse medication over 15 minutes.
2.5 mL
______
X
15 mins
Reduce if you can:
2.5mL
______
1mins
60 mins
______
1hr
X
4 mins
____
1h
=
10mL
_______
1h
NOTE: on all dosage calculation quizzes and dosage calculation questions on exams
you will be instructed to calculate the amount of the medication to administer even
if it is not safe! The purpose of these exercises is to verify your ability to do the
math, not what you would do if the medication is not safe.
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EXAMPLE OF THE ENTIRE SIX-STEP PROCESS
EXAMPLE: Patient has diagnosis of otitis media.
Order: Amoxicillin 75 mg. PO q8°
Weight: 70 lbs.
Safe Dosage: 20-40 mg/kg/day in 3 divided doses.
Drug Available: 125mg/5ml
Step 1:
Determine the safe dosage guideline. The safe dosage guideline for
Amoxicillin is 20-40 mg/kg/day.
Step 2:
Find the weight in kg.
31.82 kg
2.2 kg
70 lb
Step 3:
Calculate the maximum safe dose/ 24 hours
31.82 kg
×40 mg
1272.8 mg/24°
Step 4:
Calculate the amount ordered for 24° or per dose.
Order is for 75 mg PO q 8 hours.
q 8 hr = 3 doses/24 hours
75 mg/dose
×3 doses
225 mg/24 hours ordered
Step 5:
Determine if the dosage ordered is safe.
Compare the amount ordered for 24 hours with the maximum safe
dose.
225 mg is less than 1272.8 mg. Therefore, the dosage ordered is safe.
Step 6:
Calculate the amount of medication to be given.
Amount of Amoxicillin on hand = 125 mg/5 ml
Amount ordered is 75 mg.
75 mg
×5 ml=3 ml
125 mg
Therefore, the volume to be given is 3 ml.
Remember: If the medication is an IV infusion there will be 7 steps.
*Review Pediatric Maintenance Fluid Calculations on page 1276 Table 35.4
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PRACTICE PROBLEMS
Directions:
Complete the following sample problems. The answers are provided for you
on page 10. You are provided with the safe dosage guidelines. If you have problems with any
part of this exam, please go back and review the module or seek assistance from your theory
instructor, your clinical instructor or the nursing resource instructor.
1. Melanie has a strep infection.
The order reads: Penicillin VK 100 mg PO q 6 hrs.
Child’s weight: 31 lbs.
Drug Available: 125mg/5ml
Step 1:
What is the safe dosage for Penicillin?
15-50 mg/kg/24 hours in three to six doses
Step 2:
kg = ____________________________________________________
Step 3:
Maximum safe dose for 24 hours _____________________________
Step 4:
Amount ordered for 24 hours ________________________________
Step 5:
Is the dose safe? __________________________________________
Step 6:
Calculate the amount to be given _____________________________
2. Patrick (12 years old) has a seizure disorder.
The order reads: Phenytoin (Dilantin) 150 mg, PO, B.I.D.
Child’s weight: 110 lbs.
Drug Available: 125mg/5ml
Step 1: What is the safe dosage for Dilantin?
6 – 7 /kg/24 hours in two divided doses
Step 2:
kg = ____________________________________________________
Step 3:
Maximum safe dose for 24° __________________________________
Step 4:
Amount ordered for 24°_____________________________________
Step 5:
Is the dose safe? __________________________________________
Step 6:
Calculate the amount to be given _____________________________
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3.
Rachel (2 months old) has congestive heart failure.
The order reads: Digoxin (Lanoxin) Maintenance dose: 0.05 mg, PO, Q12h
Child’s weight: 8 lbs.
Drug Available: 0.05mg/1ml
Step 1:
What is the safe dosage for Digoxin?
Child 1 month to 2 years old:0.01-0.02 mg/kg/24 hours in two divided doses
Step 2:
kg = ____________________________________________________
Step 3:
Maximum safe dose for 24° __________________________________
Step 4:
Amount ordered for 24°_____________________________________
Step 5:
Is the dose safe? __________________________________________
Step 6:
Calculate the amount to be given _____________________________
4. Michael has a systemic infection.
The order reads: Oxacillin 200 mg, IV, q 6 h. Infuse over 15 minutes.
Child’s weight: 30 lbs.
Drug Available: 250mg/2.5ml
Step 1:
What is the safe dose for Oxacillin?
50-100 mg/kg/24 hours in four to six divided doses
Step 2:
kg = ____________________________________________________
Step 3:
Maximum safe dose for 24° __________________________________
Step 4:
Amount ordered for 24°_____________________________________
Step 5:
Is the dose safe? __________________________________________
Step 6:
Calculate the amount to be given _____________________________
Step 7:
How fast will the medication infuse (mL/h)? _____________________
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5.
Beth has post appendectomy pain.
The order reads: Morphine 10mg IV Q 2 – 4 hours PRN for pain. Infuse over 15
mins.
Child’s weight: 70 lbs.
Drug Available: 2mg/1ml
Step 1:
What is the safe dose for Morphine?
0.1mg – 0.2 mg/kg/dose IV Q 2- 4 hours PRN
6.
Step 2:
kg = ____________________________________________________
Step 3:
Maximum safe dose per dose ________________________________
Step 4:
Amount ordered per dose ___________________________________
Step 5:
Is the dose safe? __________________________________________
Step 6:
Calculate the amount to be given _____________________________
Step 7:
How fast will the medication infuse (mL/h)? _____________________
Brandon had a circumcision 1 hour ago and is fussy.
The order reads: Acetaminophen 50mg PO Q 4 hours PRN for pain.
Child’s weight: 7lbs. 8ounces
Drug Available: 160mg/5ml
Step 1:
What is the safe dose for Acetaminophen?
10 mg – 15 mg/kg/dose PO 4 hours PRN
Step 2:
kg = ____________________________________________________
Step 3:
Maximum safe dose per dose ________________________________
Step 4:
Amount ordered per dose ___________________________________
Step 5:
Is the dose safe? __________________________________________
Step 6:
Calculate the amount to be given _____________________________
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ANSWER KEY TO PRACTICE PROBLEMS
1.
2.
3.
Step 1:
given
Step 2:
4.
Step 1:
given
14.09 kg
Step 2:
13.64 kg
Step 3:
704.5 mg
Step 3:
1364 mg
Step 4:
400 mg
Step 4:
800 mg
Step 5:
Yes
Step 5:
Yes
Step 6:
4 ml
Step 6:
2.0 ml
Step 7:
8mL/h
Step 1:
given
Step 1:
given
Step 2:
50 kg
Step 2:
31.82 kg
Step 3:
350 mg
Step 3:
6.36 mg
Step 4:
300 mg
Step 4:
10 mg
Step 5:
Yes
Step 5:
No
Step 6:
6 ml
Step 6:
5 ml
Step 7:
20mL/h
Step 1:
given
Step 2:
3.64 kg
Step 3:
.07 mg
Step 4:
.1 mg
Step 5:
No
Step 6:
1 ml
5.
6.
Step 1:
Step 2:
given
3.41 kg
Step 3:
51.15 mg
Step 4:
50 mg
Step 5:
Yes
Step 6:
1.56mL
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UNIT II
Administration of Medications to Children
Upon completion of this unit, students will be able to adapt previously learned competencies
in the administration of medication to safe administration of medication to children, using a
developmental approach.
Learning Activities
1. Read Chapter 35 in Maternity and Pediatric Nursing 3rd ed. (Ricci, Kyle, Carman 2017)
2. Complete practice questions for Unit II.
3. Review answers to practice questions for Unit II on page 14.
PRACTICE QUESTIONS FOR UNIT II
1.
Parents may be encouraged to administer oral medications to their children, provided
the nurse prepares the medication and supervises its administration.
True or False
2.
3.
When administering medications that are unpalatable to children, the best nursing
action would be:
a.
Mix with milk or formula, since children like milk products.
b.
Tell the child it tastes like candy.
c.
Use a small amount of a non-essential food item to disguise the taste.
All liquid medications should be measured in a syringe.
True or False
4.
A 1 ml syringe should be used to measure volumes less than 1 ml.
True or False
5.
A child _____________ years or over can be taught to take a tablet.
6.
Best position for the infant during the administration of medications is:
7.
a.
semi-reclining on the left side.
b.
flat with the neck extended.
c.
semi-reclining.
The preferred site for IM injections in infants is:
a.
Vastus lateralis
b.
Ventral gluteal
c.
Dorsal ventral
d.
Deltoid
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8.
Oral medications may be administered in a medicine cup, after accurate measurement in
a syringe is completed, when the child is able to drink from a cup (6-8 months).
True or False
9.
It is advisable to have another nurse assist you in restraining a child for an IM injection.
True or False
10. The child should receive a detailed explanation of the injection.
True or False
11. Ear drops are instilled with the child restrained in supine position and the head turned to
the appropriate side. For a child under 3:
a.
the external auditory canal is straightened by gently pulling the pinna downward
and back.
b.
the ear is pulled up.
c.
the external auditory canal is straightened by gently pulling the pinna back and up.
12. Guidelines for IM injections in school-age children include which of the following?
a.
Inject medication as rapidly as possible.
b.
Insert needle quickly, using a dart-like motion.
c.
Penetrate skin immediately after cleansing site, before skin has dried.
d.
Have child stand, if at all possible, and if child is cooperative.
13. You need to give a medication in a capsule form to a 3 year old child. The child is not
yet able to swallow a capsule. After consulting with the pharmacist, the nurse would:
a.
dissolve it in 30cc of water and give it in a medicine cup
b.
empty the capsule into some jelly and administer it with a spoon
c.
conceal the capsule in the child’s favorite breakfast cereal
d.
mix the medication with 1 teaspoon of the child’s favorite food.
ANSWERS TO PRACTICE QUESTIONS FOR UNIT II
1.
True
8.
True
2.
C
9.
True
3.
True
10.
F
4.
True
11.
A
5.
5 years
12.
B
6.
C
13.
B
7.
A
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