Download Promoting Safe Medication Administration

SSAC2006.WY100.SG1.1
Administering Medications
to Patients
Calculating medication dosages in the clinical setting
Core Quantitative Issue
Ratios and Proportions
The safe and accurate administration of
medications is an essential nursing skill
that takes concentration and practice.
Supporting Quantitative Concepts
Conversions
XY Scatter Plot
Prepared for SSAC by
Shari Goldberg – Colby-Sawyer College
© The Washington Center for Improving the Quality of Undergraduate Education. All rights reserved. 2006
1
Overview of Module
Drug calculations are an important and valued skill for nurses. The
accurate calculation of medications during administration prevents
medication errors and potential harm to patients.
This module is designed to take you through the process of calculating
medication doses. An understanding of some basic math concepts is
an important foundation when determining the amount of medication to
be given to a patient. This module will give you an opportunity to
practice conversions and proportions, and apply these concepts to
determine accurate dosage calculations.
Slide 3-4:
•Explanation of variables in medication administration
Slide 5:
•Statement of a problem
Slide 6-8:
•Review of unit conversion and decimal placement
Slides 9-11:
•Solution of problem
Slide 12-13 :
•end of module assignment
Slides 14-16
•Glossary, appendices
2
Background Information: Conceptual Thinking
When determining the correct amount of medication to give to a
patient, there are four variables to consider:
V = the vehicle
(tablet, oral
suspension,
injectable liquid)
D = desired
amount, or the
medication
order
x = the
correct
medication
dosage
H = on hand
or available
medication
Order: Compazine
10 mg PO qid
How many mg of
Compazine are in each
tablet?
How is the medication
delivered?
The amount of medication
that you actually give to
your patient
3
Background Information: Conceptual Thinking
•
In a medication order, you will be supplied with
the desired amount (D)
•
You will be able to determine what medication
is available (H). Just look at the label.
•
The vehicle (V) is always “1” when tablets are
prescribed. When injectables or oral
suspensions are ordered V is the number of
milliliters.
•
Order: Compazine 10 mg PO qid
D = 10 mg
The medication label
What is the value of H?
Used with permission of GlaxoSmithKline
In what form will this medication be
The amount of medication that will be given (x),
is the one unknown value that you will need to
calculate.
The value of x should include a number and
the method of delivery such as PO or IM.
delivered?
V=?
You know:
•how many milligrams are ordered
•how the medication will be delivered
(tablet).
4
So, what is the value of x?
Problem
Mrs. B. is an 80-year-old woman who lives in an assisted living facility.
She has been complaining of ear pain and has a history of recurring
otitis media. On exam, her tympanic membrane is red and swollen. The
nurse practitioner diagnoses otitis media and orders:
Amoxicillin/clavulanate (Augmentin) 0.5g PO q12h.
Used with permission of GlaxoSmithKline
•How many milliliters of Augmentin need to be administered to Mrs. B.?
• How many times each day will this medication be administered?
5
Metric Conversions, Creating a Spreadsheet
Notice on Slide 5 that the medication order is in grams and the medication
label is in milligrams. You will need to convert from grams to milligrams.
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
B
Grams
0.025
0.05
0.075
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
2.50
2.75
3.00
3.25
3.50
3.75
4.00
C
D
Milligrams Kilograms
25
0.000025
50
0.00005
75
0.000075
250
0.00025
500
0.0005
750
0.00075
1000
0.001
1250
0.00125
1500
0.0015
1750
0.00175
2000
0.002
2250
0.00225
2500
0.0025
2750
0.00275
3000
0.003
3250
0.00325
3500
0.0035
3750
0.00375
4000
0.004
Let’s review conversions within the metric system.
We will create a spreadsheet to compare grams,
milligrams, and kilograms.
Recreate the spreadsheet.
•The values in column B for grams will be given.
Build a formula to find the values for column C
(milligrams) and column D (kilograms).
Looking at the spreadsheet that you have made:
•What do you notice about the relationship of grams and
milligrams? Grams and kilograms?
= cell with a number in it •If you know the value in grams, and you need to convert
to milligrams, will the number in milligrams be larger or
6
= cell with a formula in it smaller?
Metric Conversions, XY Scatter Plot
Let’s explore the information that we
entered into the spreadsheet.
Note that metric units are used in the
healthcare setting.
Recreate this graph.
Metric Conversions
For help click here.
4500
The graph compares the
number of grams with the
number of milligrams. The
number of grams is on the xaxis and the number of
milligrams is on the y-axis.
Milligrams (mg)
4000
3500
3000
2500
2000
1500
1000
500
0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Grams (g)
•What do you notice about the graph? What happens to the number of
grams when the number of milligrams increases? Why?
Looking at your graph:
• 2.0 grams = _____ milligrams?
•3500 milligrams = _____ grams?
7
Procedure: Unit conversions
As stated in the problem on Slide 5, Mrs. B. needs 0.5 g of Augmentin. We
have the medication in the medication cart, but it is in mg.
• Use a proportion to convert the order for 0.5 g to a dosage in mg.
• Refer to the graph on preceding slide to check your answer.
There are 1000 mg in 1g.
Think of this as a conversion
factor in the form of the ratio
of the number of smaller
units per one of the larger
units: 1000 mg per 1 g.
Key
To convert from the larger to the smaller unit of
measure (g to mg), you want to multiply by the
conversion ratio, 1000 mg per 1 g. To convert
from a smaller to a larger unit (for example, g to
kg), you want to divide by the conversion ratio,
1000 g per 1 kg.
Also
To multiply by 1000 (to convert grams to milligrams), move the decimal
point three spaces to the right. To divide by 1000 (to convert grams to
kilograms) move the decimal point three spaces to the left
You are ready to answer the question posed in Slide 5 
8
Solving the Problem
Now that we know that we want to give Mrs. B. 500 mg of Augmentin, how many mL of
the oral suspension should be administered? Return to the medication label in Slide 5.
The solution is 125mg/5mL. Solving the problem calls for a proportion: How many mL of
the 125mg/5mL oral suspension will deliver 500 mg of Augmentin?
1. There are a few different
methods that can be used to
achieve the same result when
calculating medication
dosages.
2. Refer to the problem in Slide 5.
Create and fill in the table below
for each variable
D=
500mg
3. Solve for X using each of the
H=
125mg
formulas below using pencil
and paper:
V=
5ml
X=
?
a)
H : V :: D : X
H D
b) V  X
c)
D
xV  X
H
The answers for formulas a,
b, and c are the same! Use
the formula that makes the
most sense to you.
9
Solving the Problem
Recreate the spreadsheet below
using the values of the variables
from Slide 9, Box 2. Solve for X.
Insert formula c (Slide 9, Box 3) to
obtain the results for cell E3.
2
3
B
D
500
C
H
125
D
V
5
E
X
20
•You have identified the four
variables involved in determining
the correct medication dose.
•Use only one of the three
formulas in Slide 9, Box 2
Does the value for X
on your spreadsheet
on this page equal the
value for X that you
completed on paper?
= (B3/C3)*D3
So now we know the answers to questions 1&2 on Slide 5:
• Mrs. B. will receive 20 mL of Augmentin q 12h
• Mrs. B will receive Augmentin two times each day.
10
Putting it all together
One goal of this module is for you to understand the variables that
are used to figure out the correct amount of medication to give
to a patient after looking at the medication order.
Let’s practice with a second example.
The medication order is:
Doxycycline 100 mg po bid X10d.
On the medication label you note that each
tablet contains 25 mg.
How many tablets will you give per dose?
1. Add a new row to your spreadsheet and
fill in the known variables (with the same
formula that you used in Slide 10).
2. Solve for x.
3. With pencil and paper, use formula
(a), (b), or (c).
4. Solve for x.
2
3
4
B
D
500
100
C
H
125
25
D
V
5
1
E
X
20
4
Is your answer using the
spreadsheet the same as the
calculation you did by hand?
11
End of Module Assignments 1
Mr. P. has an order for Tagamet: 0.4g PO bid. The drugs available are:
Bottle A
Used with permission of GlaxoSmithKline
1.
2.
3.
4.
5.
6.
Bottle B
Used with permission of GlaxoSmithKline
What is the first thing that needs to be done?
What is the formula that you will use to determine the correct dosage?
If Bottle A is available, how will you set up the formula ?
How many tablets will you give Mr. P. per dose?
If Bottle B is available, how will you set up the formula?
How many tablets will you give Mr. P. per dose?
12
End of Module Assignments 2
Mr. B. is one day post op, and is complaining of pain. He has an
order for Demerol: 35 mg IM q4-6h as needed. The drug
available is Demerol 50 mg. You are preparing to give him an
injection.
7. What additional piece of information do you need? Hint: Think of
the formula.
8. Calculate the amount of Demerol that you will give your patient.
13
Important Dosage Abbreviations
•
•
•
•
•
PO = by mouth
qid = four times per day
IM = intramuscular (injected into the muscle)
q12h = every 12 hours
bid = two times per day
Return to Slide 3
Return to Slide 4
Return to Slide 5
Return to Slide 12
14
Definitions
• Otitis media – The presence of fluid in the middle ear.
• Tympanic membrane – The eardrum.
Return to Slide 5
15
Creating a Graph
You can make a graph by
highlighting a range of data
(here, from B2 to C21) and
then clicking on the chart
wizard button:
4500
4000
Milligrams (mg)
Select a graph type (in this
case, an X-Y scatter plot
connected by a smooth line)
and follow the prompts. You
should enter text for your title
and label each of the axes.
Metric Conversions
3500
3000
2500
2000
1500
1000
500
0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
Grams (g)
Your graph should illustrate the relationship between grams and
milligrams, with grams on the x-axis and milligrams on the y-axis.
Return to Slide 7
16