IV Dosage CalculationsBasic to Complex Critical Care IV Dosage Formulas
By Sally Fox Harris RN BSN
Copyright © 2017 Sally Fox Harris RN BSNPublisher: Sound Ink 2All rights reserved.ISBN: 13: 978-0-692-64158-3ISBN-10: 0692641580 Cover Design by: Coalescent Creativewww.coalescentcreative.com
Disclaimer:The practice problems are provided to help you improve your dosage calculation skills. Every effort has been made to provide accurate dosage ranges and drug supply mixes within the practice problems. When working in a clinical setting always use APPROVED medication references.
Any comments? Please send to: [email protected]
To my husband Dan,Thank you for building an office space just for me. A seized opportunity to decorate—I mean, work on this book.
To my twin sister Sue,Your witty input infused the task of generating hundreds of mathematical equations a fun endeavor. OK, so the word fun, it’s a stretch.
To my brave kids, Holle, Glory, David, Nate and Nick, Thank you for your honest and helpful application of red ink onto the manuscripts.
To my Father-in-Law Jack, “The Wordist”, One skilled in the imaginative use of words.
To my childhood friend Linda,Cheers to you. You got me across the finish line. Cheers to us.
Dedication
iv
Table of Contents
Introduction vi
Twelve Rights of Medication Administration vii
Chapter 1IV Push 1The Formula Method
Chapter 2 Basic IV Dosage Formulas 9Gravity and IV Pump Systems
Chapter 3 A Comparison Study 23Dimensional Analysis, Ratio-Proportion, Wrinkle Method Chapter 4 The Wrinkle Method 29Critical Care IV Dosage Formulas Chapter 5 Building Confidence ...Practice problems 41The Wrinkle Method Approach Chapter 6 Building Confidence ... Solutions 49Solutions for Chapter 5
v
Chapter 7 Unit Conversion 65Changing Units of Measurement
Chapter 8 Reconstitution and Dilution 75Of Powder and Liquid Medications Chapter 9 Formulas to Go 89A Quick Reference: IV Dosage Calculation Formulas
Need to know:
• Basic medical terminology, medications and administration • How-to round numbers up or down • How-to cancel out like units (used with unit conversion, Chapter 7) • Division and multiplication
Table of Contents
vi
Scary as it may sound, having just passed the nursing board NCLEX examination, I was now the RN entrusted to provide care for patients in the Cardiovascular Intensive Care Unit, CVICU. Most of the CVICU patients required multiple IV lines. Often, over the course of a 12 hour shift, those IV lines would become a huge tangled mess, which, I was sure, had to be the handy work of gremlins lurking just under the bed.
Gremlins, however, were the least of my worries. I had to calculate flow rates that delivered the right dose of medication to the patient. My dosage calculation skills, well, let’s just say, lacked proficiency. To my rescue, and in the name of patient safety, a fellow RN showed me a quick and easy method for calculating complex IV dosage rates. Today, I call that method the wrinkle method.
It’s called the wrinkle method because, according to the dictionary, wrinkle means a change in customary procedure or method. The wrinkle method, unlike the customary methods of dimensional analysis and ratio-proportion, uses a group of formulas that make complex IV dosage calculations easy, even when titrating.
There are, in addition to the above mathematical methods, several other tools that are commonly used to determine right dose delivery for critical care IV infusion drugs.
The most utilized tool is the programmable (smart) IV infusion pump. It has an awesome bedside feature in that it can perform dosage calculations for you; however, to ensure accurate calculations, great caution must be taken when inputting requested information.
Another handy tool is the IV drug dosage chart. It requires excellent hand eye coordination and, when working with non-standard drug mixes, it may have limited value.
Whatever method you choose—for patient safety—always double check for right dose delivery.
Introduction
vii
Twelve Rights of Medication Administration
When administering any medication, for patient safety, the Rights of Medication Administration must be followed. The Rights, depending on the source, may vary in number and order; however, this book addresses only one—Right Dose.
Twelve Rights of Medication Administration1. Right Patient2. Right Time 3. Right Route4. Right Dose5. Right Response6. Right Reason7. Right Documentation8. Right Assessment & Evaluation9. Right Client Education10. Right to Refuse Medication11. Right Expiration Date
1
The easiest approach to calculating IV push medications is to use the formula method.
Unlike the traditional methods of dimensional analysis and ratio-proportion, the formula method is simple, straight forward and bedside friendly. Therefore, to keep IV push dosage calculations easy, only instructions for the formula method are covered. Please note that some IV push medications may be supplied in a form that is not suitable for administration until it is reconstituted or diluted. Reconstitution or dilution are done PRIOR to any dosage calculation.
A review on how-to reconstitute and dilute can be found in Chapter 8, page 83.
IV Push The Formula Method
Chapter 1
2
Understanding Drug Concentration
Drug concentration: (Strength) Drug concentration describes how strong or weak a medication mixture is. It identifies how much drug and how much liquid are in the mixture. Example: 10 mg of a drug mixed with 10 mL of a liquid. Written: 10 mg/10 mL
Final concentration: Final concentration is the same as the drug concentration only described in smaller terms.Example: Drug concentration: 10 mg/10 mL is reduced to a smaller term. Final concentration: 1 mg/mL Measurements used in drug concentrations:Drugs are measured in: mg (milligrams) mcg (micrograms) g (grams) units (units)
Liquids are measured in: mL (milliliters)
Chapter 1
IV Push Drug concentration
3
The Formula Method
The Formula:
Explanation of formula:(O) Order = Ordered Dose(H) Have = the amount of drug (mg, mcg, g, units).(V) Volume = the amount of liquid (mL).
× (O) Order
Volume (mL) = mL to administer(H) Have
I V Push The Formula Method
4
Chapter 1 I V Push
The Formula Method/Example
Example: Drug concentration: Zofran 40 mg/20 mL
(O) Order: Zofran 4 mg to be given IV push (IVP)(H) Have: 40 mg (V) Volume: 20 mLHow many ____ mL will you administer to deliver the right dose of 4 mg?
× (O) Order
Volume (mL) = mL to administer(H) Have
× =(O) 4 mg
(V) 20 mL 2 mL(H) 40 mg You will administer 2 mL.
Example: Final concentration: Zofran 2 mg/mL
Drug concentration: Zofran 40 mg/20 mL is reduced to a final concentration.Final concentration: 2 mg/mL(O) Order: Zofran 4 mg to be given IVP (H) Have: Zofran 2 mg(V) Volume: 1 mL How many _____ mL will you administer to deliver the right dose of 4 mg?
× (O) Order
Volume (mL) = mL to administer(H) Have
× ( = 2 (O) 4 mg
V) 1mL mL(H) 2 mg
You will administer 2 mL.
5
IV Push Practice Problems
The Formula:
1. Order: Demerol 25 mg IVP q 4 hr Have: Demerol 100 mg/2 mL Administer: _____ mL
2. Order: Lasix 20 mg SIVP over 1-2 min Have: Lasix 100 mg/10 mL Administer: _____ mL
3. Order: Benadryl 12.5 mg IVP Have: Benadryl 50 mg /mL Administer: _____ mL 4. Order: Fentanyl 25 mcg IV push now. Have: Fentanyl 200 mcg /2 mL Administer: _____ mL 5. Order: Labetalol 0.25 mg/kg slow IVP over 2 min Have: Labetalol 100 mg/20 mL Wt: 84.5 kg Ordered dose is: _____ mg Administer: _____ mL
6. Ordered: Romazicon 0.2 mg IVP now Have: Romazicon 0.5 mg/5 mL Administer: _____ mL 7. Order: Vasotec 0.625 mg IVP over 5 min, repeat in one hour if needed Have: Vasotec 1.25 mg/2 mL Administer: _____ mL
× (O) Order
Volume (mL) = mL to administer(H) Have
IV Push Practice problems
6
IV Push Practice Problems
8. Order: Digoxin 0.125 mg IVP Have: Digoxin 0.5 mg/mL Administer: _____ mL
9. Ordered: Fentanyl 75 mcg IVP over 3-5 min Have: Fentanyl 250 mcg/5 mL Administer: _____ mL
10. Order: Bumex 1 mg IVP now Have: 2.5 mg/10 mL Administer: _____ mL
Chapter 1 IV Push
Practice problems
7
IV Push Practice Solutions
The Formula:
1. 0.5 mL Order: Demerol 25 mg IVP q 4 hr Have: Demerol 100 mg/2 mL
× =
25 mg2 mL 0.5 mL
100 mg
2. 2 mL Order: Lasix 20 mg slow IVP (SIVP) over 1-2 min. Have: Lasix 100 mg/10 mL
× =20 mg
10 mL 2 mL100 mg
3. 0.25 mL Order: Benadryl 12.5 mg IVP Have: Benadryl 50 mg /mL
× =12.5 mg
1 mL 0.25 mL50 mg
4. 0.25 mL Order: Fentanyl 25 mcg IV push now. Have: Fentanyl 200 mcg /2 mL
× =25 mcg
2 mL 0.25 mL200 mcg
× (O) Order
Volume (mL) = mL to administer(H) Have
IV Push Practice solutions
8
IV Push Practice Solutions
5. 21 mg 4.2 mL Order: Labetalol 0.25 mg/kg slow IVP Have: Labetalol 100 mg/20 mL Wt: 84.5 kg Calculate Order:
× =0.25 mg 84.5 kg 21 mg
Dosage Calculation
× = 4.221 mg
20 mL mL100 mg
6. 2 mL Order: Romazicon 0.2 mg IVP Have: Romazicon 0.5 mg/ 5 mL
× 5 = 2 0.2 mg
mL mL0.5 mg
7. 1 mL Order: Vasotec 0.625 mg IVP Have: Vasotec 1.25 mg/2 mL
× 2 = 10.625 mg
mL mL1.25 mg
Chapter 1 IV Push
Practice solutions
9
IV Push Practice Solutions
8. 0.25 mL Order: Digoxin 0.125 mg IVP Have: Digoxin 0.5 mg/mL
×1 = 0.25 0.125 mg
mL mL0.5 mg
9. 1.5 mL Order: Fentanyl 75 mcg IVP Have: Fentanyl 250 mcg/5 mL
× 5 = 1.5 75 mcg
mL mL250 mcg
10. 4 mL Order: Bumex 1 mg IVP Have: 2.5 mg/10 mL
×10 = 4 1 mg
mL mL2.5 mg
IV Push Practice solutions
11
There are two delivery systems used to administer IV infusion medications.
The Gravity SystemWhen using the gravity system calculate a drip rate (gtt/min).
The IV Pump SystemWhen using the IV pump system calculate a flow rate (mL/hr).
Chapter 2
Basic IV Dosage Formulas Gravity and IV Pump Systems
12
Gravity System Overview
The Gravity System uses the Drops Per Minute (DPM) formula to calculate a drip rate (gtt/min); It regulates how fast or slow the IV fluid should infuse.
The drip rate (gtt/min) is controlled by a mechanical device: • The most common is the roller clamp; It’s part of the IV tubing. • The flow regulator uses a dial to manually set a drip rate; It’s added
to the IV tubing.
In some clinical settings, like the ER, when an exact drip rate may not be critical, the speed is approximated instead of calculated. Example: The ER nurse, when infusing IV fluids like Normal Saline or Lactate Ringers, may approximate the drip rate: Slow speed: TKO = To Keep Open Medium speed Fast speed: WO = Wide Open
If the drip rate has been calculated, the drops should be counted for one minute to ensure accuracy.
Drops Per Minute (DPM) terms: • The drip rate (gtt/min) is how fast or slow the medication is infusing. • The drip factor, also called drop factor, is the number of drops of fluid per mL (gtt/mL). Each IV tubing has a drip factor located on the IV tubing package.
Common Drip Factors (gtt/mL) for IV tubing:A. Mini or Micro drip set - Used for infants, children and sensitive medications. 60 gtt/mL B. Macro drip set - Used to deliver large volumes or to infuse quickly. 10 gtt/mL 15 gtt/mL 20 gtt/mL
Chapter 2
The Gravity System Overview
13
Drops per Minute (DPM) formula
To change a pump rate (mL/hr) to a gravity rate (gtt/min)
Note: IV drip rates (gtt/min) require whole numbers and may need to be rounded up or down to the nearest whole number. Example: 12.6 gtt/min = 13 gtt/min
Gravity Examples:
1. Using the DPM formula, calculate the drip rate (gtt/min).
Order: Zantac 50 mg/100 mL to infuse over 20 minutesIV tubing: 10 gtt/mL (drip factor)What is the drip rate (gtt/min)? _______
The drip rate is 50 gtt/min. 2. Change a pump rate (mL/hr) to a gravity drip rate (gtt/min).
The pump is infusing at 50 mL/hr ,using a 10 gtt/mL tubing, what will the drip rate (gtt/min) be?
The drip rate is 8 gtt/min.
×=
total volume to be infused (mL) drip factor (gtt/mL)drip rate (gtt/min)
total infusion time in minutes
×=
infusion rate (mL/hr) drip factor (gtt/mL)drip rate (gtt/min)
60 minutes
×=
total volume to be infused (mL) drip factor (gtt/mL)drip rate (gtt/min)
total infusion time in minutes
× = 50
100 mL 10 gtt/mLgtt/min
20 minutes
50 mL/hr × 10 gtt/mL = 8 gtt/min
60 min
The Gravity System Drops per Minute (DPM) Formula
14
Gravity System Practice Problems
Calculate the following drip rates (gtt/min) using the DPM formula. Drops Per Minute (DPM) Formula:
1. Order: Give 50 mL IVPB (IV piggy back) over 30 minutesIV tubing: 10 gtt/mL (drip factor)Drip rate (gtt/min): _____
2. Order: Infuse 1 liter Normal Saline over 8 hoursIV tubing: 15 gtt/mLDrip rate (gtt/min): _____
3. Order: Give 1 liter Normal Saline over one hourIV tubing: 10 gtt/mLDrip rate (gtt/min) : _____
4. Order: Give LR at 125 mL/hrIV tubing: 10 gtt/mLDrip rate (gtt/min): _____
Solutions on page 15
×=
total volume to be infused (mL) drip factor (gtt/mL)drip rate (gtt/min)
total infusion time in minutes
Chapter 2
Gravity System Practice Problems
15
Solutions ... Gravity System Practice Problems
1. 17 gtt/min Order: 50 mL over 30 minutes IV tubing: 10 gtt/mL
×=
50 mL 10 gtt/mL17 (gtt/min)
30 minutes
2. 31 gtt/min Order: 1 liter over 8 hours IV tubing: 15 gtt/mL1,000 mL 5 gtt/mL
31 (gtt/min)8 hr 60 minutes (480 minutes)
× 1=
×
3. 167 gtt/min Order: 1 liter over one hour IV tubing: 10 gtt/mL
× =
1,000 mL 10 gtt/mL167 (gtt/min)
60 minutes
4. 21 gtt/min Order: LR at 125mL/hr IV tubing: 10 gtt/mL
× =
infusion rate (mL/hr) drip factor (gtt/mL)drip rate (gtt/min)
60 minutes
× 10 = 21
125 (mL/hr) (gtt/mL) (gtt/min)
60 minutes
Gravity System Practice Solutions
16
IV Pump System
The IV infusion pump system uses a programmable IV pump. The flow rate (mL/hr) is controlled electronically—based on the input information.
Depending on the IV pump, flow rates (mL/hr) may need to be rounded up or down to the nearest whole number. Example: 12.3 mL/hr = 12 mL/hr
IV Pump System Formulas
For basic IV infusion medications, there are three formulas.
1. Flow Rate (mL/hr)
2. Infusion Time
3. Infusion Volumes
=total volume to infuse (mL)
mL/hrtime in hours (hr)
=total volume to infuse (mL)
infusion timemL/hr
× =infusion rate (mL/hr) infusion time infusion volumes
Chapter 2IV Pump System
Basic IV Infusion Formulas
17
Examples for Basic IV Infusion Pump Formulas
1. Calculate Flow Rate (mL/hr)
Order: 1 Liter to infuse over 12 hours Convert: 1 Liter = 1,000 mL
=1,000 (mL)
83 mL/hr12 (hr)
2. Calculate Infusion Time Order: 1 Liter Normal Saline at 125 mL/hr Convert: 1 Liter = 1,000 mL
=total volume to infuse (mL)
infusion timemL/hr
3. Calculate Infusion Volumes Order: Normal Saline 150 mL/hr for 3 hours
=total volume to infuse (mL)
mL/hrtime in hours (hr)
= 8 1,000 (mL)
hours125 mL/hr
× =infusion rate (mL/hr) infusion time infusion volumes
× 3 = 450 150 (mL/hr) (hr) mL
IV Pump System Examples of Basic IV Infusion Formulas
18
Calculate Flow Rate (mL/hr)
=total volume to infuse (mL)
mL/hrtime in hours (hr)
1. Order: Normal Saline 500 mL over 3 hoursmL/hr: _____
2. Order: Ampicillin 500 mg/100 mL over 30 minmL/hr: ____
3. Order: Antibiotic 2 g/100 mL infuse over 45 minutesmL/hr: _____
4. Order: LR 1,000 mL over 6 hoursmL/hr: _____
5. Order: Truth Serum 25 mL over 10 minutesmL/hr: _____
Solutions on page 21
Chapter 2
IV Pump System Practice Problems
19
Calculate Infusion Time =
total volume to infuse (mL)infusion time
mL/hr
1. Order: 1 Liter Banana Bag at 125 mL/hrInfusion Time: _____
2. Order: 40 Meq KcL in 100 mL IV at 75 mL/hrInfusion Time: _____
3. Order: Normal Saline 500 mL at 50 mL/hrInfusion Time: _____
4. Order: Lasix 100 mg/100 mL at 15 mL/hrInfusion Time: _____
5. Order: Normal Saline 1 Liter at 200 mL/hrInfusion Time: _____
Solutions on page 22
IV Pump System Practice Problems
20
Calculate Infusion Volumes
1. Order: LR infuse at 75 mL/hr over 8 hours
Total Volume Infused: _____
2. Order: Normal Saline at 200 mL/hr over 4 hoursTotal Volume Infusion: _____
3. Order: Lasix at 8 mL/hr times 10 hoursTotal Volume Infused: _____
4. Order: Banana Bag at 125 mL/hr over 8 hoursTotal Volume Infused: _____
5. Order: D5W at 50 mL/hr x 6 hoursTotal Volume Infused: _____
Solutions on page 23
× =infusion rate (mL/hr) infusion time infusion volumes
Chapter 2
IV Pump System Practice Problems
21
Solutions ... Flow Rate (mL/hr)
1. 167 mL/hr Order: Normal Saline 500 mL over 3 hours
= 167 500 (mL)
mL/hr3 (hr)
2. 200 mL/hr Order: Ampicillin 500 mg/100 mL over 30 min
= 200
100 (mL)mL/hr
0.5 (hr) 3. 133 mL/hr
Order: Antibiotic 2 g/100 mL to infuse over 45 minutes Convert: 10 minutes into hours.
=45 min
x(hr) ×1 hr
1 60 min= 0.75 hr
= 133
100 (mL)mL/hr
0.75 (hr)
4. 167 mL/hr Order: LR 1,000 mL over 6 hours
= 167
1,000 (mL)mL/hr
6 (hr)
5. 156 mL/hr Order: Truth Serum 25 mL over 10 minutes Convert: 10 minutes into hours.
10 minX (hr) =
1 hr2 60 min
× 0.16 hr=
25 mLx (hr) 156 mL/hr
0.16 (hr)= =
=total volume to infuse (mL)
mL/hrtime in hours (hr)
IV Pump System Solutions
22
Solutions ... Infusion Time
1. 8 hours Order: Banana Bag 1 Liter at 125 mL/hr 1 Liter = 1,000 mL
= 8 1,000 (mL)
hours125 mL/hr
2. 1 hour 30 min Order: 40 Meq KcL in 100 mL IV at 75 mL/hr
= 1 100 (mL)
hours 30 min75 mL/hr
3. 10 hours Order: Normal Saline 500 mL at 50 mL/hr
= 10
500 (mL)hours
50 mL/hr
4. 6.6 hours Order: Lasix 100 mg/100 mL at 15 mL/hr
100 (mL) 6.6 hours
15 mL/hr=
5. 5 hours Order: Normal Saline 1 Liter at 200 mL/hr
Convert: 1 Liter = 1,000 mL
1,00 (mL)hours
200 mL/hr= 5
=total volume to infuse (mL)
infusion timemL/hr
Chapter 2
IV Pump System Solutions
23
Solutions ... Infusion Volumes
1. 600 mL Order: LR infuse at 75 mL/hr over 8 hours
× 8 = 600 75 (mL/hr) (hr) mL
2. 800 mL Order: Normal Saline at 200 mL/hr over 4 hours
× 4 ( = 800 200 (mL/hr) hr) mL
3. 80 mL Order: Lasix at 8 mL/hr times 10 hours
× 10 ( = 80 8 (mL/hr) hr) mL
4. 1,000 mL Order: Banana Bag at 125 mL/hr over 8 hours
× 8 ( = 1, 000 125 (mL/hr) hr) mL
5. 300 mL Order: D5W at 50 mL/hr x 6 hours
× 6 ( = 300 50 (mL/hr) hr) mL
× =infusion rate (mL/hr) infusion time infusion volumes
IV Pump System Solutions
25
Traditionally, complex critical care IV dosage calculations are solved using dimensional analysis and/or ratio-proportion methods. There is, however, an easier method. It’s the wrinkle method.
The wrinkle method is a name given to a group of formulas; They are easy to remember and simple to use.
To demonstrate how easy the wrinkle method formulas are compared to the traditional formulas, a comparison study is used.
The comparison study shows how each method, dimensional analysis, ratio-proportion and the wrinkle method, is used to claculate a flow rate (mL/hr).Each method will use the same critical care IV dosage calculation problem.
Since the focus of this chapter is to compare the three methods above, the wrinkle method is not introduced in detail. Chapter 4 will explain step-by-step how the wrinkle method works.
Chapter 3
A Comparison Study Dimensional Analysis, Ratio-Proportion, Wrinkle Method
26
Comparison Problem Order: Dopamine to infuse at 10 mcg/kg/min Have: Dopamine 400 mg in 250 mL Wt: 65 kg
Solve for the flow rate (mL/hr) using:
• Dimensional Analysis • Ratio-proportion • Wrinkle Method
Chapter 3
The Comparison Study Comparison problem
27
Dimensional Analysis Method
Dimensional analysis is a mathematical system using conversion factors to move from one unit of measurement to a different unit of measurement. Dimensional analysis formula: Comparison problem: Order: Dopamine 10 mcg/kg/min. Have: Dopamine 400 mg in 250 ml Wt: 65 kg Solve for the Flow Rate (mL/hr): _____
1. Draw a line with desired units at the end.
2. Place known values and conversion factors on the line. Position them either on the top or bottom to facilitate the cancellation of undesired units.
Order: 10 mcg/kg/min Drug concentration: 400 mg/250 mL Wt: 65 kg
Conversion Factors: 1 mg =1,000 mcg 60 minutes = 1 hr 10 mcg 250 mL 65 kg 60 minutes 1mg
mL/hrkg minutes 400 mg 1 1 hr 1,000 mcg
× × × × =×
3. Cancel out like units. Leave only desired units.
10 mcgkg × minutes
250 mL×
400 mg65 kg
×60 minutes
×1
1 mg×
1 hr 1,000 mcg= mL/hr
4. Multiply / Divide
10 250 mL 65 60 1× × × × = 24.4 mL/hr
1 400 1 1 hr 1,000
The flow rate is 24 mL/hr.
a b c d eX
b c d e f= × × × ×
mL hr
The Comparison Study Dimensional Analysis Method
28
Ratio-Proportion Method
Ratio is used to make a comparison between two things. A ratio is written like a fraction: Proportion says two ratios are equal.A proportion is written: Ratio-proportion formula:
Comparison problem: Order: Dopamine 10 mcg/kg/min. Have: Dopamine 400 mg in 250 mL Wt: 65 kg Solve for the flow rate (mL/hr): _____
1. Convert, mg to mcg (1 mg = 1,000 mcg) Have: Dopamine 400 mg/250 mL 400 mg 1, 000 400, 000 mcg× =
Now Have: Dopamine 400,000 mcg in 250 mL
2. Multiply ordered dose
10 mcg 65 kg/min 650 mcg/min× =
Total dose to be infused is 650 mcg/min. What is the flow rate (mL/hr) _____ ?
(Continued on page 29)
a bor
b a
a c
b d=
known value known valueknown value desired value
=
Chapter 3
The Comparison Study The Ratio-Proportion Method
29
Ratio-Proportion Method ... Continued
3. Set up a Ratio-Proportion formula This will determine how many mL of solution contain 650 mcg.
400,000 mcg 650 mcg250 mL (x) mL
=
4. Cross - Multiply400, 000 mcg (x) mL 250 mL 650 mcg× = × 5. Divide both sides by 400,000 mcg 400,000 mcg400,000 mcg
250 mL mg (x) mL
400,000 mcg× 650
× =
250 mL mcg(x)mL
× 650 =
400,000 mcg
mL 0.40= The Order is 650 mcg/min. There are 650 mcg/minute in 0.40 mL. What is the flow rate(mL/hr) _____ ? 6. Set up a Dimensional Analysis formula.
mL/hr
0.40 mL1 minutes
× 60 minutes
=
× = 24
mL/hr1 hr
600.40 mL mL/hr
1 hr
The flow rate is 24 mL/hr.
The Comparison Study The Ratio-Proportion Method ... continued
30
Chapter 3
The Comparison Study The Wrinkle Method
The Wrinkle Method
The wrinkle method defines a group of formulas. Each formula generates a value called the BedsideValue (BV). The (BV) is then used to calculate both the flow rate (mL/hr) and dosage rate.
mcg/kg/min:
Comparison problem: Order: Dopamine 10 mcg/kg/min. Have: Dopamine 400 mg in 250 mL Wt: 65 kg Solve for the flow rate (mL/hr): _____
1. Convert mg to mcg (1 mg = 1,000 mcg) Have: Dopamine 400 mg/250 mL
Now Have: Dopamine 400,000 mcg/250 mL
2. Calculate the BedsideValue (BV)÷ ÷ ÷ =400, 000 mcg 250 mL 60 minutes 65 kg 0.41(BV)
BedsideValue (BV) = 0.41
3. Calculate the flow rate (mL/hr) Use the BedsideValue (BV) 0.41
Flow Rate =
The flow rate is 24 mL/hr.
÷mcg ÷ mL ÷ 60 minutes kg = BedsideValue (BV)
400 mg 1, 000 400, 000 mcg× =
=10
24 mL/hr0.41
= Order
mL/hr(BV)
31
The Comparison Study How-to check Flow Rate (mL/hr) Accuracy
How to Check Flow Rate (mL/hr) Accuracy
To ensure the right dose of medication is delivered to the patient, all flow rates (mL/hr) must be checked for accuracy.
If the flow rate was calculated using dimensional analysis or ratio-proportion methods, the dosage calculations must be repeated to check for flow rate accuracy. This approach is time consuming, and the same mistake(s) could be repeated.
If the flow rate (mL/hr) was calculated using the wrinkle method, use the dosage rate formula below to check for flow rate accuracy.
Dosage Rate Formula: Dosage Rate = (mL/ hr) × Bedside Value (BV)
Example:Using the Wrinkle Method to Solve the Comparison problem: Order: Dopamine 10 mcg/kg/min. mL/hr: 24 Bedside Value (BV): 0.41 If the flow rate is 24 mL/hr, then the calculated dosage rate is 10mcg/kg/min.
= (mL/ hr) × (BV) dosage rate × (Β =24 mL / hr V) 0.41 9.8mcg / kg / min
33
Introducing a refreshing alternative from the customary methods of dimensional analysis and ratio-proportion. It’s the wrinkle method.
The wrinkle method, unlike the traditional methods that can be confusing to use, makes solving and titrating complex critical care IV dosage calculations easy. No need to depend on programmable IV pumps and/or drug dosage charts any longer. Instead of a crutch, use them as a tool to check flow rate (mL/hr) accuracy—ensuring right dose delivery.
Chapter 4
The Wrinkle Method Critical Care IV Dosage Formulas
34
Wrinkle Method Overview
• The wrinkle method is a collection of seven formulas. • Two basic formulas • Five formulas that have slight variations from the basic formulas • The goal of each formula is to calculate a value. • That value is called the BedsideValue (BV).
• The BedsideValue (BV) represents: • The drug concentration you have on hand (i.e., 50 mg/250 mL). • The patient’s weight (in kg), if required.
• The BedsideValue (BV) is used to calculate both: • Flow rate (mL/hr) • Dosage rate
The wrinkle method has three easy steps
Step One: Convert, if required Example: Convert mg to mcg or lbs to kg
Step Two: Calculate the BedsideValue (BV) • To calculate the BedsideValue (BV), use one of the wrinkle method formulas. • The (BV) is used in step three to calculate a flow rate (mL/hr) and dosage rate.
Step Three: Calculate both: • Flow Rate (mL/hr) Round up or down as needed. • Dosage Rate
Calculating both flow rate (mL/hr) and dosage rate is a quick way tocheck for right dose delivery.
Chapter 4
The Wrinkle Method Overview
35
Basic Knowledge for Critical Care Continuous IV Medications
The units of measurement used for critical care continuous IV medications are: • mg (milligrams) • mcg (micrograms) • g (grams) • units (units)
The dosage rates for critical care continuous IV medications are written: • mg/min • mcg/min • mcg/kg/min • units/min • mg/hr • units/hr • units/kg/hr
The Wrinkle Method Basic Knowledge
36
Dosage Rate Formulas ending with min • mg/min • mcg/min • mcg/kg/min • units/min These formulas ending in min are divided by 60 minutes. This is the basic formula: mg/min mcg/min
mcg/kg/min
units/minunits ÷ mL ÷ 60 minutes = BedsideValue (BV)
mg ÷ mL ÷ 60 minutes = BedsideValue (BV)
mcg ÷ mL ÷ 60 minutes = BedsideValue (BV)
÷mcg ÷ mL ÷ 60 minutes kg = BedsideValue (BV)
Chapter 4
The Wrinkle Method Dosage Rate Formulas
37
The Wrinkle Method Dosage Rate Formulas
Dosage Rate Formulas ending with hr • mg/hr • units/hr • units/kg/hr These formulas ending in hr are NOT divided by 60 minutes. This is the basic formula: mg/hr
units/hrunits ÷ mL = BedsideValue (BV) units/kg/hr
÷units ÷ mL kg = BedsideValue (BV)
mg ÷ mL = BedsideValue (BV)
38
Using the BedsideValue (BV)
The BedsideValue (BV) is used to calculate both the flow rate (mL/hr) and the dosage rate. Flow Rate = Dosage Rate = (BV) = BedsideValue
= Order
mL/hr(BV)
= (mL/ hr) × (BV) dosage rate
Chapter 4
The Wrinkle Method Using the Bedside Value (BV)
39
mg/min
How -to use:1. This is the basic formula for dosage rates ending in min. 2. Divided by 60 minutes
Example: Order: Cordarone IV 0.5 mg/min Have: Cordarone 900 mg/500 mL Solve for mL/hr: _____
Step One: Convert, No conversion required. Order is in mg, drug concentration is in mg, (900 mg/500 mL)
Step Two: Calculate the BedsideValue (BV)
Step Three: Calculate both Flow Rate =
Dosage Rate =
mcg ÷ mL ÷ 60 minutes = BedsideValue (BV)
÷ ÷ =
÷ ÷ =
mg mL 60 minutes BV
900 mg 500 mL 60 minutes 0.03 BV
= Order
mL/hr(BV) =
0.517 mL/hr
0.03
= (mL/ hr) × (BV) dosage rate × =17 0.03 0.5 mg
The Wrinkle Method Example (mg/min)
40
mcg/min
How-to use: 1. Use the basic formula: mg ÷ mL ÷ 60 minutes = (BV) 2. Convert mg to mcg 3. Divided by 60 minutes
Example: Order: Nitroglycerin 10 mcg/min Have: Nitroglycerin 50 mg/250 mL Solve for mL/hr: _____
Step One: Convert, mg to mcg, (1 mg = 1,000 mcg) Order is in mcg, drug concentration is in mg, (50 mg/250 mL) Now Have: 50,000 mcg/250 mL
Step Two: Calculate the BedsideValue (BV)
Step Three: Calculate both
Flow Rate =
Dosage Rate =
mcg ÷ mL ÷ 60 minutes = BedsideValue (BV)
× =50 mg 1, 000 50, 000 mcg
÷ ÷ =
÷ 250 ÷ = 3.33
mcg mL 60 minutes BV
50, 000 mcg mL 60 minutes BV
= 3 10
mL/hr3.33
= Order
mL/hr(BV)
× =3 3.33 10 mcg= (mL/ hr) × (BV) dosage rate
Chapter 4
The Wrinkle Method Example (mcg/min)
41
mcg/kg/min
How-to use: 1. Use the basic formula: mg ÷ mL ÷ 60 minutes =(BV) 2. Convert mg to mcg 3. Insert kg 4. Divide by 60 minutes
Example: Order: Dopamine 10 mcg/kg/min Have: Dopamine 400 mg/250 mL Wt: 84.5 kg Solve for mL/hr: _____
Step One: Convert, mg to mcg (1 mg = 1,000 mcg) Order is in mcg, drug concentration is in mg, (400 mg/250 mL)
Now Have: 400,000 mcg/250 mL
Step Two: Calculate the BedsideValue (BV)
Step Three: Calculate both Flow Rate = Dosage Rate =
÷mcg ÷ mL ÷ 60 minutes kg = BedsideValue (BV)
× = 400400 mg 1, 000 , 000 mcg
mcg ÷ mL ÷ 60 minutes ÷ kg=BV
400,000 mcg ÷ 250 mL ÷ 60 minutes ÷ 84.5 kg = 0.31 BV
= 10
32 mL/hr0.31
= Order
mL/hr(BV)
= (mL/ hr) × (BV) dosage rate × =32 0.31 10 mcg
The Wrinkle Method Example (mcg/kg/min)
42
units/min
How-to use:1. Use the basic formula: mg ÷ mL ÷ 60 minutes = (BV) 2. Convert mg to units 3. Divide by 60 minutes
Example: Order: Vasopressin 0.04 units/min Have: Vasopressin 100 units/100 mL Solve for mL/hr: _____
Step One: Convert, No conversion required. Order is in units, drug concentration is in units, (100 units/100 mL)
Step Two: Calculate the BedsideValue (BV)
Step Three: Calculate both Flow Rate = Dosage Rate =
units ÷ mL ÷ 60 minutes = BedsideValue (BV)
÷ ÷ =
÷100 ÷ = 0.016
units mL 60 minutes BV
100 Units mL 60 minutes (BV)
= 0.04
2.5 mL/hr0.016
= Order
mL/hr(BV)
= (mL/ hr) × (BV) dosage rate 2.5 × 0.016 = 0.04 units
Chapter 4
The Wrinkle Method Example (units/min)
43
mg/hr
How-to use:1. This is the basic formula for dosage rates ending in hr. 2. Do NOT divide by 60 minutes
Example: Order: Morphine 2 mg/hr Have: Morphine 50 mg/50 mL Solve for mL/hr: _____
Step One: Convert, No conversion required. Order is in mg, drug concentration is in mg, (50 mg/50 mL)
Step Two: Calculate the BedsideValue (BV)
Step Three: Calculate both
Flow Rate =
Dosage Rate =
mg ÷ mL = BedsideValue (BV)
÷ =
÷ =
mg mL BV
50 mg 50 mL 1 BV
= 2 2
mL/hr1
= Order
mL/hr(BV)
= (mL/ hr) × (BV) dosage rate 2 × 1 = 2 mg
The Wrinkle Method Example (mg/hr)
44
units/hr How-to use:
1. Use the basic formula: mg ÷ mL =(BV)2. Convert mg to units 3. Do NOT divide y 60 minutes
Example: Order: Heparin 1,300 units/hr Have: Heparin 20,000 units/500 mL Solve for mL/hr: _____
Step One: Convert, No conversion required. Order is in units, drug concentration is in units, (20,000 units/500 mL) Step Two: Calculate the BedsideValue (BV)
Step Three: Calculate both Flow Rate =
Dosage Rate =
units ÷ mL = BedsideValue (BV)
÷ =
÷ =
units mL BV
20, 000 units 500 mL 40 BV
= 33 1,300
mL/hr40
= Order
mL/hr(BV)
= (mL/ hr) × (BV) dosage rate 32.5 × 40 = 1, 300 units
Chapter 4
The Wrinkle Method Example (units/hr)
45
The Wrinkle Method Example (units/kg/hr)
units/kg/hr
How-to use:
1. Use the basic formula: mg ÷ mL = BedsideValue (BV)2. Convert mg to units 3. Insert kg4. Do NOT divide y 60 minutes
Example: Order: Heparin 18 units/kg/hr Have: Heparin 25,000 units/250 mL Wt: 55 kg Solve for mL/hr: _____
Step One: Convert, No conversion required. Order is in units, drug concentration is in units, (25,000 units/250 mL)
Step Two: Calculate the BedsideValue (BV)
Step Three: Calculate both
Flow Rate =
Dosage Rate =
÷units ÷ mL kg = BedsideValue (BV)
÷ ÷ =
÷ ÷ =
units mL kg BV
25,000 units 250 mL 55 kg 1.8 BV
= 1018
mL/hr1.8
= Order
mL/hr(BV)
= (mL/ hr) × (BV) dosage rate 10 ×1.8 = 18 units
47
It’s easy to solve complex critical care IV dosage calculations when using the wrinkle method formulas. They’re easy to remember, simple to work and powerful at the bedside. With a little practice, you will soon have the confidence to calculate your own flow rates (mL/hr).
And always – for patient safety – double check the accuracy of your flow rates for right dose delivery.
Conversion of units may be required in some of the calculations. For a review, please see Chapter 7, page 73.
Chapter 5
Building Confidence ... Practice Problems The Wrinkle Method Approach
48
Wrinkle Method Formulas … Review
Dosage Rate Formulas ending with min • mg/min • mcg/min • mcg/kg/min • units/min
These formulas ending in min are divided by 60 minutes. This is the basic formula: mg/min mcg/min
mcg/kg/min
units/min
Dosage Rate Formulas ending with hr • mg/hr • units/hr • units/kg/hr
These formulas ending in hr are NOT divided by 60 minutes.This is the basic formula: mg/hr
units/hrunits ÷ mL = BedsideValue (BV)
units/kg/hr
÷units ÷ mL kg = BedsideValue (BV)
mg ÷ mL ÷ 60 minutes = BedsideValue (BV)
mcg ÷ mL ÷ 60 minutes = BedsideValue (BV)
÷mcg ÷ mL ÷ 60 minutes kg = BedsideValue (BV)
units ÷ mL ÷ 60 minutes = BedsideValue (BV)
mg ÷ mL = BedsideValue (BV)
Chapter 5
Building Confidence … Practice Problems Wrinkle Method Formulas - Review
49
Using the BedsideValue (BV)
The BedsideValue (BV) is used to calculate both the Flow Rate (mL/hr) and the Dosage Rate.
Flow Rate =
Dosage Rate =
The wrinkle method has three easy steps
Step One: Convert, if required Example: Convert mg to mcg or lbs to kg
Step Two: Calculate the BedsideValue (BV) • Calculate the BedsideValue (BV) by using one of the wrinkle method formulas. • The (BV) is used in step three to calculate a flow rate (mL/hr) and dosage rate. Step Three: Calculate both: • Flow Rate (mL/hr) Round up or down as needed. • Dosage Rate
Calculating both flow rate (mL/hr) and dosage rate is a quick way todouble check for right dose delivery.
OrderFlow Rate (mL/ hr) =
Bedside Value (BV)
Dosage Rate = (mL/ hr) × Bedside Value (BV)
Building Confidence ... Practice Problems Using the Bedside Value (BV)
50
Solve for: • BedsideValue (BV) • Flow Rate (mL/hr): may need to be rounded up or down • Dosage Rate:
1. Order: Amiodarone 0.5 mg/min Have: 450 mg/250 mL BV: _____ mL/hr: _____
2. Order: Labetalol 1 mg/min Have: 500 mg/250 mL BV: _____ mL/hr: _____
3. Order: Procainamide 2 mg/min Have: Procainamide 4 g/500 mL BV: _____ mL/hr: _____ If the infusion rate is 25 mL/hr, what is the dosage rate _____ ?
4. Order: Lidocaine 2 mg/min Have: 2 g/250 mL BV: _____ mL/hr: _____
5. Order: Diltiazem 8 mg/hr Have: 100 mg/100 mL BV: _____ mL/hr: _____
6. Order: Furosemide 2 mg/hr Have: 100 mg/100 mL BV: _____ mL/hr: _____
Solutions to questions 1 - 6 found on pages 56-58
Chapter 5
Building Confidence ... Practice Problems Wrinkle Method Approach
51
7. Order: Levophed 8 mcg/min Have: Levophed 4 mg/250 mL BV: _____ mL/hr : _____
8. Order: Isuprel 5 mcg/min Have: Isupprel 2 mg/250 mL BV: _____ mL/hr: _____ If the infusion rate is 46 mL/hr, what is the dosage rate _____ ?
9. Order: Norepinephrine 2 mcg/min Have: Norepinephrine 8 mg/250 mL BV: _____ mL/hr: _____
10. Order: Epinephrine 2 mcg/min Have: Epinephrine 2 mg/250 mL BV: _____ mL/hr: _____
11. Order: Brevibloc 150 mcg/kg/min Have: Brevibloc 2.5 g/250 mL Wt: 88 kg BV: _____ mL/hr: _____ 12. Order: Dopamine 15 mcg/kg/min Titrate: Decrease Dopamine by 1 mcg/kg/min every 30 minutes Have: Dopamine 400 mg/250 mL Wt: 50 kg BV: _____ mL/hr: _____ Titrate: 1 mcg/kg/min = _____ mL/hr
Solutions to questions 7- 12 found on pages 59-62
Building Confidence ... Practice Problems Wrinkle Method Approach
52
13. Order: Primacor 0.5 mcg/kg/min Have: Primacor 40 mg/200 mL Wt: 81 kg BV: _____ mL/hr: _____
14. Order: Start Diprivan 25 mcg/kg/min Titrate: Increase 5 mcg/kg/min every 5 minutes to desired sedation Have: Diprivan 1,000 mg/100 mL Wt: 78 kg BV: _____ mL/hr: _____ Titrate: 5 mcg/kg/min = _____ mL/hr
15. Order: Insulin 10 units/hr Have: Insulin 100 units/100 mL BV: _____ mL/hr: _____
16. Order: Heparin 800 units/hr Have: Heparin 25,000 units/250 mL BV: _____ mL/hr: _____ 17. Order: Heparin 18 units/kg/hr Have: Heparin 25,000 units/250 mL Wt. 88 kg BV: _____ mL/hr: _____ 18. Order: Nitroglycerine 16 mcg/min Have: 50 mg/250 mL BV: _____ mL/hr: _____
Solutions to questions 13- 18 found on pages 63-66
Chapter 5
Building Confidence ... Practice Problems Wrinkle Method Approach
53
19. Order: Vecuronium to start at 0.8 mcg/kg/min Titrate: To desired effect, max of 1.2 mcg/kg/min Have: 100 mg in 250 mL Wt: 81 kg BV: _____ 0.8 mcg/kg/min = _____ mL/hr 1.2 mcg/kg/min = _____ mL/hr If the infusion rate is 15 ml/hr, what is the dosage rate _____ ?
20. Order: Vasopressin 0.2 – 0.4 units/min Titrate: to desired effect, max of 0.4 units/min Have: 200 units in 250 mL BV: _____ 0.3 units/min = _____ mL/hr If the infusion rate is 19 mL/hr, what is the dosage rate ______ ?
21. Order: Norepinephrine 2-40 mcg/min Titrate: to desired effect, max of 40 mcg/min Have: Norepinephrine 4 mg/250 mL BV: _____ 2 mcg/min = _____ mL/hr 5 mcg/min = _____ mL/hr If the infusion rate is 50 mL/hr, what is the dosage rate _____ ?
22. Order: Neosynephrine 50 - 300 mcg/min Have: 30 mg/500 mL (1 mg = 1,000 mcg) BV: _____ If the infusion rate is 75 mL/hr, what is the dosage rate _____ ?
23. Order: Midazolam 1 mg/hr Have: Midazolam 100 mg/100 mL BV: _____ mL/hr: _____
Solutions to questions 19- 23 found on pages 67-70
Building Confidence ... Practice Problems Wrinkle Method Approach
54
Chapter 5
Building Confidence ... Practice Problems Wrinkle Method Approach
24. Order: Vasopressin 0.04 units/min Have: Vasopressin 20 units/100 mL BV: _____ mL/hr: _____
25. Order: Dobutamine 10 mcg/kg/min Have: Dobutamine 500 mg/250 mL Wt: 77 kg BV: _____ mL/hr: _____
Solutions to questions 24- 25 found on pages 71
55
Chapter 6
Building Confidence ... Solutions Solutions for Chapter 5
Each practice problem from Chapter 5 is solved using one of the wrinkle method formulas.
Calculations are shown step-by-step.
56
1. BV: 0.03 mL/hr: 17 Order: Amiodarone 0.5 mg/min Have: 450 mg/250 mL
Step One: Convert, No conversion required.Step Two: Calculate the (BV) BedsideValue
Step Three: Calculate both
2. BV: 0.03 mL/hr: 33 Order: Labetalol 1 mg/min Have: 500 mg/250 mL
Step One: Convert, No conversion required.Step Two: Calculate the (BV) Bedside Value
÷ ÷ =500 mg 250 mL 60min 0.03 BV
Step Three: Calculate both
450 mg ÷ 250 mL ÷ 60 min = 0.03 BV
= 0.5
17 mL/hr0.03
OrderFlow Rate (mL/hr) =
BV
Dosage Rate mL/hr BV= × 0.03 mg17 × = 0.5
133 mL/hr
0.03 =
OrderFlow Rate (mL/hr) =
BV
Dosage Rate mL/hr BV= × 17 0.03 mg×
Chapter 6
Building Confidence ... Solutions Practice solutions
57
3. BV: 0.13 mL/hr: 15 Doage rate is 3.25 mg/min at 25 mL/hr Order: Procainamide 2 mg/min Have: Procainamide 4 g/500 mL If the infusion rate is 25 mL/hr, what is the dosage rate? _____
Step One: Convert g to mg, (1 g = 1,000 mg)
Step Two: Calculate the (BV) Bedside Value
Step Three: Calculate both
Dosage rate at 25 mL/hr = 25 × 0.13 = 3.25 mg
4. BV: 0.13 mL/hr: 15 Order: Lidocaine 2 mg/min Have: 2 g/250 mL
Step One: Convert g to mg, (1 g = 1,000 mg)
Step Two: Calculate the (BV) Bedside Value
Step Three: Calculate both
4 gmg =
1,000 mg1 1 g
× 4, 000 mg=
4, 000 mg mL 60min 0.13 BV÷ 500 ÷ =
2 mL/hr
0.13= 15
OrderFlow Rate (mL/hr) =
BV
Dosage Rate mL/hr BV= × 15 0.13 mg× = 2
15 0.13 mg× = 2
2 gmg =
1,000 mg1 1 g
× , 000 mg= 2
2, 000 mg mL 60min 0.13 BV÷ 250 ÷ =
2 mL/hr
0.13= 15
OrderFlow Rate (mL/hr) =
BV
Dosage Rate mL/hr BV= ×
Building Confidence ... Solutions Practice solutions
58
5. BV: 1 mL/hr: 8 Order: Diltiazem 8 mg/hr Have: 100 mg/100 mL
Step One: Convert, No conversion required.Step Two: Calculate the (BV) Bedside Value This order/formula ends in hr, do not divide by 60 minutes.
Step Three: Calculate both
6. BV: 1 mL/hr: 2 Dosage Rate: Order: Furosemide 2 mg/hr Have: Furosemide 100 mg/100 mL
Step One: Convert, No conversion required. Step Two: Calculate the (BV) Bedside Value This order/formula ends in hr, do not divide by 60 minutes. 100 mg mL BV÷100 = 1
Step Three: Calculate both
100 mg mL BV÷100 = 1
8mL/hr
1= 8
OrderFlow Rate (mL/hr) =
BV
Dosage Rate mL/hr BV= × mg8 ×1 = 8
2mL/hr
1= 2
OrderFlow Rate (mL/hr) =
BV
Dosage Rate mL/hr BV= × mg2 ×1 = 2
Chapter 6
Building Confidence ... Solutions Practice solutions
59
7. BV: 0.26 mL/hr: 31 Order: Levophed 8 mcg/min Have: Levophed 4 mg/250 mL
Step One: Convert mg to mcg, (1 mg = 1,000 mcg) Step Two: Calculate the (BV) Bedside Value
Step Three: Calculate both
8. BV: 0.13 mL/hr: 38 Dosage Rate is 6 mcg/min at 46 mL/hr Order: Isuprel 5 mcg/min Have: Isuprel 2 mg/250 mL If the infusion rate is 46 mL/hr, what is the dosage rate? _____
Step One: Convert mg to mcg, (1 mg = 1,000 mcg) Step Two: Calculate the (BV) Bedside Value
Step Three: Calculate both
Dosage rate at 25 mL/hr = × = 46 0.13 6 mcg
4 mgmcg =
1,000 mcg1 1 mg
× 000 mcg= 4,
4, 000 mcg mL 60min V÷ 250 ÷ = 0.26 Β
8mL/hr
0.26= 31
OrderFlow Rate (mL/hr) =
BV
Dosage Rate mL/hr BV= ×
2mcg =
mg 1,000 mcg1 1 mg
× 000 = 2, mcg
2, 000 mcg mL 60min V÷ 250 ÷ = 0.13 Β
5mL/hr
0.13= 38
OrderFlow Rate (mL/hr) =
BV
Dosage Rate mL/hr BV= × mcg38 × 0.13 = 5
Building Confidence ... Solutions Practice solutions
60
9. BV: 0.53 mL/hr: 4 Order: Norepinephrine 2 mcg/min Have: Norepinephrine 8 mg/250 mL
Step One: Convert mg to mcg, (1 mg = 1,000 mcg)
Step Two: Calculate the (BV) BedsideValue
Step Three: Calculate both
10. BV: 0.13 mL/hr: 15 Order: Epinephrine 2 mcg/min Have: Epinephrine 2 mg/250 mL
Step One: Convert mg to mcg, (1 mg = 1,000 mcg) Step Two: Calculate the (BV) Bedside Value Step Three: Calculate both
8 mgmcg =
1,000 mcg1 1 mg
× 000 mcg= 8,
8, 000 mcg mL 60min V÷ 250 ÷ = 0.53 Β
2mL/hr
0.53= 4
OrderFlow Rate (mL/hr) =
BV
Dosage Rate mL/hr BV= × mcg4 × 0.53 = 2
2 mgmcg =
1,000 mcg1 1 mg
× 000 mcg= 2,
2, 000 mcg mL 60min V÷ 250 ÷ = 0.13 Β
2mL/hr
0.13= 15
OrderFlow Rate (mL/hr) =
BV
Dosage Rate mL/hr BV= × mcg15 × 0.13 = 2
Chapter 6
Building Confidence ... Solutions Practice solutions
61
11. BV: 1.89 mL/hr: 79 Order: Brevibloc 150 mcg/kg/min Have: Brevibloc 2.5 g/250 mL Wt: 88 kg
Step One: Convert g to mcg, (1 g = 1,000,000 mcg) Step Two: Calculate the (BV) BedsideValue
Step Three: Calculate both
2.5 gmcg =
1,000,000 mcg1 1 g
× mcg= 2,500, 000
2, 500, 000 mcg mL 60min 88 kg V÷ 250 ÷ ÷ = 1.89 Β
150mL/hr
1.89= 79
OrderFlow Rate (mL/hr) =
BV
Dosage Rate mL/hr BV= × mcg79 ×1.89 = 149.3
Building Confidence ... Solutions Practice solutions
62
12. BV: 0.53 mL/hr: 28 Titrate 1 mcg/kg/min = 2 mL/hr Order: Dopamine 15 mcg/kg/min Titrate: decrease Dopamine by 1 mcg/kg/min every 30 minutes Have: Dopamine 400 mg/250 mL Wt: 50 kg
Step One: Convert mg to mcg, (1 mg = 1,000 mcg) Step Two: Calculate the (BV) Bedside Value
Step Three: Calculate both
Titrate: 1 mcg/kg/min
400 mgmcg =
1,000 mcg1 1 mg
× 000 mcg= 400,
÷ 250 ÷ ÷ = 0.53 Β400, 000 mcg mL 60 min 50 kg V
15mL/hr
0.53= 28
OrderFlow Rate (mL/hr) =
BV
Dosage Rate mL/hr BV= × mcg28 × 0.53 = 15
1mL/hr
0.53= 2
OrderFlow Rate (mL/hr) =
BV
Dosage Rate mL/hr BV= × mcg2 × 0.53 = 1
Chapter 6
Building Confidence ... Solutions Practice solutions
63
13. BV: 0.04 mL/hr: 13 Order: Primacor 0.5 mcg/kg/min Have: Primacor 40 mg/200 mL Wt: 81 kg
Step One: Convert mg to mcg, (1 mg =1,000 mcg) Step Two: Calculate the (BV) Bedside Value
Step Three: Calculate both
40 mgmcg =
1,000 mcg1 1 mg
× 000 mcg= 40,
÷ 200 ÷ ÷ = 0.04 Β40,000 mcg mL 60 min 81 kg V
= 13 0.5
mL/hr0.04
OrderFlow Rate (mL/hr) =
BV
Dosage Rate mL/hr BV= × 13× 0.04 = 0.5 mcg
Building Confidence ... Solutions Practice solutions
64
14. BV: 2.13 mL/hr: 12 Titrate: 5 mcg/kg/min = 2 mL/hr Order: Start Diprivan 25 mcg/kg/min Titrate: Increase 5 mcg/kg/min every 5 minutes Have: Diprivan 1,000 mg/100 mL Wt: 78 kgStep One: Convert mg to mcg, (1 mg = 1,000 mcg) Step Two: Calculate the (BV) Bedside Value
Step Three: Calculate both
Titrate: 1 mcg/kg/min
=1,000 mg
mcg ×1,000 mcg
1 1 mg= 1, 000, 000 mcg
1, 000, 000 mcg mL 60min kg V÷100 ÷ ÷ 78 = 2.13 Β
25mL/hr
2.13= 12
OrderFlow Rate (mL/hr) =
BV
Dosage Rate mL/hr BV= × mcg12 × 2.13 = 25
5mL/hr
2.13= 2
OrderFlow Rate (mL/hr) =
BV
Dosage Rate mL/hr BV= × mcg2 × 2.13 = 4.26
Chapter 6
Building Confidence ... Solutions Practice solutions
65
15. BV: 1 mL/hr: 10 Order: Insulin 10 units/hr Have: Insulin 100 units/100 mL
Step One: Convert, No conversion required. Step Two: Calculate the (BV) Bedside Value This order/formula ends in hr, do not divide by 60 minutes.
Step Three: Calculate both
16. BV: 100 mL/hr: 8 Order: Heparin 800 units/hr Have: Heparin 25,000 units/250 mL
Step One: Convert, No conversion required. Step Two: Calculate the (BV) Bedside Value This order/formula ends in hr, do not divide by 60 minutes. Step Three: Calculate both
100 units 100 mL 1 BV÷ =
10mL/hr
1= 10
OrderFlow Rate (mL/hr) =
BV
Dosage Rate mL/hr BV= × 10 1 10 units× =
25, 000 units mL 100 BV÷ 250 =
800 mL/hr
100= 8
OrderFlow Rate (mL/hr) =
BV
Dosage Rate mL/hr BV= × 100 units8 × = 800
Building Confidence ... Solutions Practice solutions
66
Chapter 6
Building Confidence ... Solutions Practice solutions
17. BV: 1.13 mL/hr: 16 Order: Heparin 18 units/kg/hr Have: Heparin 25,000 units/250 mL Wt. 88 kg
Step One: Convert, No conversion required. Step Two: Calculate the (BV) Bedside Value This order/formula ends with hr, do not divide by 60 minutes Step Three: Calculate both
18. BV:3.33 mL/hr: 5 Order: Nitroglycerine 16 mcg/min Have: 50 mg/250 mL
Step One: Convert mg to mcg, (1 mg =1,000 mcg)
Step Two: Calculate the (BV) Bedside Value Step Three: Calculate both
25, 000 units mL kg BV÷ 250 ÷ 88 = 1.13
18mL/hr
1.13= 16
OrderFlow Rate (mL/hr) =
BV
Dosage Rate mL/hr BV= × 16 1.13 18 units× =
50 mgmcg =
1,000 mcg1 1 mg
× mcg= 50, 000
50, 000 mcg mL 60min V÷ 250 ÷ = 3.33 Β
OrderFlow Rate (mL/hr) =
BV16
mL/hr3.33
= 5
Dosage Rate mL/hr BV= × mcg5 × 3.33 = 16
67
Building Confidence ... Solutions Practice solutions
19. BV: 0.08 mL/hr 10 Dosage Rate is 0.95 mcg/kg/min at 15 mL/hr Order: Vecuronium to start at 0.8 mcg/kg/min Titrate: For effect to a max of 1.2 mcg/kg/min Have: 100 mg in 250 mL Wt: 81 kg If the infusion rate is 15 ml/hr, what is the dosage rate _____ ?Step One: Convert mg to mcg, (1 mg = 1,000 mcg) Step Two: Calculate the (BV) Bedside Value
Step Three: Calculate both
Dosage rate at 15 mL/hr
100 mgmcg =
1,000 mcg1 1 mg
× mcg= 100, 000
100, 000 mcg mL 60min kg V÷ 250 ÷ ÷ 81 = 0.08 Β
0.8 mcg mL/hr
0.08= 10
OrderFlow Rate (mL/hr) =
BV
Dosage Rate mL/hr BV= ×
mcg15 × 0.08 = 1.2
1.2 mcg mL/hr
0.08= 15
mcg10 × 0.08 = 0.08
68
Chapter 6
Building Confidence ... Solutions Practice solutions
20. BV: 0.013 23 mL/hr for 0.3 units/min Dosage rate is 0.25 units/min at 19 mL/hr Order: Vasopressin 0.2 – 0.4 units/min titrate for effect. Have: 200 units in 250 mL
Step One: Convert, No conversion required. Step Two: Calculate the (BV) Bedside Value
Step Three: Calculate both
Dosage rate at 19 mL/hr
200 units 250 mL 60min 0.013 BV÷ ÷ =
0.3 unitsmL/hr
0.013 = 23
OrderFlow Rate (mL/hr) =
BV
Dosage Rate mL/hr BV= × units23× 0.013 = 0.3
19 units× 0.013 = 0.25
69
Building Confidence ... Solutions Practice solutions
21. BV: 0.26 2 mcg/min = 8 mL/hr 5 mcg/min = 19 mL/hr Dosage Rate is 13 mcg/min at 50 mL/hr . Order: Norepinephrine 2-40 mcg/min Titrate: to desired effect, max of 40 mcg/min Have: Norepinephrine 4 mg/250 mL BV: _____ 2 mcg/min = _____mL/hr 5 mcg/min = _____mL/hr If the infusion rate is 50 mL/hr, what is the dosage rate _____?
Step One: Convert, mg to mcg (1 mg = 1,000 mcg) Step Two: Calculate the (BV) Bedside Value
Step Three: Calculate both
Dosage rate at 8 mL/hr =
4 mgmcg =
1,000mcg1 1 mg
× mcg= 4, 000
4, 000 mcg mL 60 min V÷ 250 ÷ = 0.26 Β
2 mcg/minmL/hr
0.26 BV= 8
OrderFlow Rate (mL/hr) =
BV
5 mcg/minmL/hr
0.26 BV= 19
Dosage Rate mL/hr BV= × 50 × 0.26 = 13 mcg
70
Chapter 6
Building Confidence ... Solutions Practice solutions
22. BV: 1 Dosage rate is 75 mcg/min at 75 mL/hr Order: Neosynephrine 50 - 300 mcg/min Have: Neosynephrine 30 mg/500 mL Step One: Convert, mg to mcg (1 mg = 1,000 mcg)
Step Two: Calculate the (BV) Bedside Value Step Three: Calculate both
23. BV: 1 mL/hr: 1 Order: Midazolam 1 mg/hr Have: Midazolam 100 mg/100 mL BV: _____ mL/hr: _____
Step One: Convert, No conversion required.Step Two: Calculate the (BV) Bedside Value This order/formula ends in hr, do not divide by 60 minutes.
Step Three: Calculate both
30 mgmcg =
1,000 mcg1 1 mg
× mcg= 30, 000
30,000 mcg mL 60 min BV÷ 500 ÷ = 1
OrderFlow Rate (mL/hr) =
BV100
mL/hr3.33
= 30
Dosage Rate mL/hr BV= × mcg75 ×1 = 75
100 mg mL BV÷100 = 1
1mL/hr
1= 1
OrderFlow Rate (mL/hr) =
BV
Dosage Rate mL/hr BV= × mg1×1 = 1
71
Building Confidence ... Solutions Practice solutions
24. BV: 0.003 mL/hr: 13 Order: Vasopressin 0.04 units/min Have: Vasopressin 20 units/100 mL BV: _____ mL/hr: _____
Step One: Convert, No conversion required.Step Two: Calculate the (BV) Bedside Value
Step Three: Calculate both
25. BV: 0.43 mL/hr: 23 Order: Dobutamine 10 mcg/kg/min Have: Dobutamine 500 mg/250 mL Wt: 77 kg BV: _____ mL/hr: _____
Step One: Convert, mg to mcg (1 mg = 1,000 mcg)
Step Two: Calculate the (BV) Bedside Value
Step Three: Calculate both
20 units 100 mL 60min 0.003 BV÷ ÷ =
OrderFlow Rate (mL/hr) =
BV0.04
mL/hr0.003
= 13
Dosage Rate mL/hr BV= × 13 × 0.003 = 0.009 mL units
500 mgmcg =
1,000 mcg1 1 mg
× mcg= 500, 000
500, 000 mcg mL 60min kg V÷ 250 ÷ ÷ 77 = 0.43 Β
OrderFlow Rate (mL/hr) =
BV10
mL/hr0.43
= 23
Dosage Rate mL/hr BV= × mL V mcg23 × 0.43 Β = 10
73
When solving a dosage calculation, conversion of units is often required. For example, a patient’s weights may be changed from pounds (lbs) to kilograms (kg). Or, a measurement of medication may be changed from milligrams (mg) to micrograms (mcg). Centimeters (cm) may be used instead of inches (in). Those changes are called unit conversion.
Chapter 7
Unit Conversion Changing Units of Measurement
74
Unit Conversion is changing from one unit of measurement to another unit of measurement with the same value.
Units of Measurement common to the world of nursing: Units of Measurement Value• Fahrenheit to Celsius Temperature • Pounds to Kilograms Weight • Inches to Centimeters Length • Hours to Minutes Time• Gallons to Liters Volume• Quarts to Milliliters Volume
Conversion Factors are a mathematical tool used to change the units of measurement without changing it’s value. Example of Conversion Factors: 2.2 lbs (pounds) = 1 kg (kilogram) 1 inch = 2.54 cm (centimeters)
Conversion factors are written in a ratio (fraction) format.
Example: Conversion Factor =1 kg 2.2 lbs
Ratio Format 2.2 lbs1 kg
or
1 kg2.2 lbs
Chapter 7
Unit Conversion Terms
75
Unit Conversion Formula and example
Conversion Formula:
The desired unit (the unit of measure you want to convert to) will always be placed on top of the conversion factor ratio.
Example:Convert 175 lbs to kg175 lbs = _____ kg Conversion factor: 1 kg = 2.2 lbs
Since the desired unit is kg, kg is placed on top of the conversion factor ratio.
175 lbskg =
1 kg1 2.2 lbs
×
kg 175 1 kg) 2.2
kg 79.5
= ( × ÷
=
To check the answer for accuracy reverse the conversion process. Thedesired unit is placed on top of the conversion factor.
79.5 kglbs =
2.2 lbs ×
1 1 kg
lbs = 79.5 × 2.2 lbs
lbs = 174.9 Round Up
given unit Desired UnitDesired Unit
1 given unit= ×
76
Common Conversion Factors
Weight1 milligram (mg) = 1,000 micrograms (mcg)1 kilogram (kg) = 2.2 pounds (lbs)1 kilogram (kg) = 1,000 grams (g)1 gram (g) = 1,000 milligrams (mg)1 gram (g) = 1,000,000 micrograms (mcg)750 milligrams (mg) = 10 milliequivalent (mEq)1 Grains (gr) = 60 - 65 milligrams (mg)
Volume
1 (mL) = 15 – 16 (gtt) drops1 (L) liter = 1,000 (mL) milliliters1 (tsp) teaspoon = 5 (mL) milliliters1 (tbsp.) tablespoon = 15 (mL) milliliters1 (oz) ounce = 30 (mL) millilitersDrams (dr), not commonly used today
Length1 inch = 2.54 centimeters (cm)39.4 inches = 1 meter (m)1 meter (m) = 1,000 centimeters (cm)
Temperature Fahrenheit to Celsius
Celsius to Fahrenheit
( 32) 1.8F C° − ÷ = °
( 1.8) 32C F° × + = °
Chapter 7
Unit Conversion Common Conversion Factors
77
Practice Problems
Conversion Formula:
Remember, the desired unit (the unit of measurement you want to convert to) is placed on top of the conversion factor ratio.
1. Convert 250 mg to mcg
2. Convert 400,000 mcg to mg
3. Convert 1,500 mL to L
4. Convert 2 g to mg
5. Convert 60 inches to cm
6. Convert 210 lbs to kg
7. Convert 49 kg to lbs
8. Convert 5’ 7” (5 foot 7 inches) to inches 9. Convert 500 mg to mEq
10. Convert 98.6 Fahrenheit to Celsius, (use the formula below) Fahrenheit to Celsius ( 32) 1.8F C° − ÷ = °
given unit Desired UnitDesired Unit
1 given unit= ×
Unit Conversion Practice Problems
78
Solutions
1. mcg = 250,000 250 mg = _____ mcg Conversion factor: 1 mg = 1,000 mcg (desired unit goes on top)
=250 mg
mcg ×1,000 mcg
1 1 mg
= 250 × 1,000
=
mcg mcg
mcg 250,000 mcg
2. mg = 400 400,000 mcg = _____ mg Conversion factor: 1 mg = 1,000 mcg
=400,000 mcg
mg ×1 mg
1 1,000 mcg
= ÷
=
mg 400,000 mg 1,000
mg 400 mg
3. L = 1.5 1,500 mL = _____ Liters (L) Conversion factor: 1 Liter (L) = 1,000 milliliters (mL)
1,500 mLL=
1 L×
1 1,000 mL
= 1,500 ÷ 1,000
= 1.5
L L
L L
Chapter 7
Unit Conversions Solutions
79
Solutions
4. mg = 2,000 2 grams (gm) = _____ mg Conversion factor: 1 gram (gm) = 1,000 mg
=2 g
mg ×1,000 mg
1 1 g
= 2 × 1,000
= 2, 000
mg mg
mg mg
5. cm = 152.4 60 inches = _____ centimeters (cm) Conversion factor: 1 inch = 2.54 cm
=60 inch
cm ×2.54 cm
1 1 inch
= 60 × 2.54
= 152.4
cm cm
cm cm
6. kg = 113.6 210 lbs = ______ kg Conversion factor: 2.2 lbs = 1 kg
=250 lbs
kg ×1 kg
1 2.2 lbs
= 250 ÷ 2.2
=
kg kg
kg 113.6 kg
Unit Conversions Solutions
80
Solutions
7. lbs= 107.8 49 kg = ______ lbs Conversion factor: 2.2 lbs = 1 kg
=49 kg
lbs ×2.2 lbs
1 1 kg
= ×
=
lbs 49 2.2 lbs
lbs 107.8 lbs
8. Inches = 67 5’7” = ______ inches Conversion factor: 1 ft = 12 inches
= 5 ft
in ×12 inches
1 1 ft+ 7
= (5 × 12 ) + 7
= 60 + 7
=
in
in in in
in in
in 67 in
Chapter 7
Unit Conversions Solutions
81
Solutions
9. mEq 6.66 500 mg = _____ mEq Conversion factor: 750 mg = 10 mEq
500 mgmEq =
10 mEq×
1 750 mg
meq = (500 × 10 meq) ÷ 750
meq = 5,000 meq ÷ 750
meq = 6.66 meq
10.
This conversion requires a formula instead of a conversion factor.
( F 32) 1.8 C
( 98.6 32) 1.8 37 C
÷
÷ =
° - = °
° - °
37 Celsius°98.6 Fahrenheit _____ Celsius=° °
Unit Conversions Solutions
83
To put your mind at ease, when working with medications that require reconstitution or dilution, there are two basic steps to follow.
Step One: Add a liquid to the medication.Step Two: Solve the Dosage Calculation.
Dosage calculations are done after reconstituting or diluting.
× (O) Order
Volume (mL) = mL to administer(H) Have
Chapter 8
Reconstitution and Dilution Of Powder and Liquid Medications
84
Terms
Reconstitution is adding a liquid to a powder medication prior to administering. Dilution is adding a liquid to a liquid medication prior to administering.
Diluent: When diluting medications, the liquid used is called the diluent.When reconstituting, the liquid used is a solvent, but may be referred to as the diluent. • Diluent is a liquid that makes a mixture thinner or weaker. • Solvent is a liquid that dissolves a solid resulting in a solution. • Diluent is measured in mL (milliliters). • Common Diluents:
• Sterile Water with or without preservative • Normal Saline (NS), also called 0.9% Sodium Chloride (NaCl) • Bacteriostatic Sterile Water
Solute: (Drug)A solid or liquid that is dissolved or diluted in a liquid. • Solute is measured in:
• mg (milligrams) • mcg (micrograms) • g (grams) • units (units)
Drug concentration: (Strength) Drug concentration describes how strong or weak a medication mixture is. It identifies how much drug and how much liquid are in the mixture. Example: 10 mg of a drug mixed with 10 mL of a liquid. Written: 10 mg/10 mL
Final concentration: The final concentration is the same as the drug concentration only described in smaller terms. Example: Drug concentration: 10 mg/10 mL is reduced to a smaller term. Final concentration: 1 mg/mL
Drug concentration is defined after you have added the liquid to the medication.
Chapter 8
Reconstitution and Dilution Terms
85
Guidelines
To Reduce the Risk of Medication Errors or other adverse patient outcomes associated with reconstitution or dilution of medications always follow the current guidelines:
• Drug manufacturer’s recommendations (medication label or insert)• Hospital’s guidelines• Pharmacist’s instructions
Medication labels will tell you:• If reconstitution or dilution is required prior to administration• What kind of liquid (diluent) to add• How many (mL) to add • The resulting concentration after reconstitution or diluting (example: 2 mg/1 mL)
Properly label the syringe with:• Patient name:• Drug name: • Drug concentration: after reconstitution or dilution • Dose ordered:• Directions for administration: (e.g., slow IV push) • Expiration date & time:
Reconstitution and Dilution Guidelines
86
Chapter 8
Reconstitution and Dilution When to Dilute
When to Dilute
Dilution is adding a liquid to a liquid medication prior to administering.
Not all IV Push (IVP) medications require dilution prior to administration. 1 Unnecessary diluting practices can lead to: • Unlabeled syringes • Mislabeled syringes • Potential contamination • Dosage errors • Other drug administration errors Dilute if: • Drug manufacturer or hospital guidelines recommend. • Dilution will increase accurate dosage control during administration. • Dilution will improve patient comfort or reduce risk of injury at injection site.
1Dilution guidelines: • Follow drug manufacture and/or hospital guidelines for Standard Volume Diluent with resulting concentrations. • Properly label the drug concentration after diluting. • Always conduct a double check of drug dose before administrating.
1. ISMP, Institute for Safe Medication Practices. Acute Care, ISMP Medication Safety Alert. Some IV Medications Are Diluted Unnecessarily In Patient Care Areas, Creating Undue Risk. 2014; June 19.
87
Reconstitution and Dilution Dilution Example
Dilution Example
Order: Morphine 2 mg IV push nowHave: Morphine 10 mg/1 mL
Dilution is recommended because: • Diluting will increase accurate right dose delivery. A drug concentration of 10 mg/1 mL is to concentrated for an accurate dose to be administered. • Diluting will improve patient comfort Morphine may burn during administration. Goal: Drug concentration of 10 mg/10 mL Final concentration of 1 mg/1 mL This will increase accurate dose control and patient comfort when administering.
Step One: Add a liquid (diluent) to the medication Diluent: per guidelines, sterile water or normal saline Have: 10 mg of medication in 1 mL of liquid Goal: 10 mg/10 mL Add: 9 mL plus 1 mL = 10 mL Now Have: 10 mg/10 mL or 1 mg/mL
Step Two: Dosage Calculation (may use either concentration)
Or
× (O) Order
Volume (mL) = mL to administer(H) Have
× =(O) 2 mg
1 mL (V) 2 mL(H) 1 mg
× = 2 (O) 2 mg
10 mL (V) mL (H) 10 mg
88
• Prepares Initials: Advanced Dilution Example
Order: Penicillin G 1,000,000 units IV q 8 hrHave: 5,000,000 units
Per the medication label, dilution is required prior to administration.
You will need to know:A. What is the diluent? B. How many _____ mL of diluent to add to the medication for a final concentration of 1,000,000 units/mL?C. How many _____ mL to administer for a 1,000,000 unit dose? Step One: Add the liquid (diluent) Per the medication label the diluent is sterile normal saline. Instructions read: For a Final Concentration Add Sterile Normal Saline 250,000 units/mL 20 mL 500,000 units/mL 10 mL 1,000,000 units/mL 5 mL Goal: Select the final concentration that best matches the order.
The Order is 1,000,000 units Based on the medication label instructions, for a final concentration of 1,000,000 units/mL, add 5 mL of sterile normal saline.
(Continued on page 89)
Chapter 8
Reconstitution and Dilution Reconstitution Example
89
Advanced Dilution Example Continued
Step Two: Dosage Calculation
Order: 1,000,000 units Have: 1,000,000 units/mL
Answers: A. Diluent is sterile normal salineB. Add 5 mL C. Administer 1 mL for a 1,000,000 unit dose.
× (O) Order
Volume (mL) = mL to administer(H) Have
× = 1
÷ × =
1,000,000 units1 mL mL to administer
1,000,000 units
1,000,000 1,000,000 1 mL 1 mL
Reconstitution and Dilution Advanced Dilution Example
90
Chapter 8
Reconstitution and Dilution Reconstitution example
Reconstitution Example
Order: Ampicillin 500 mg IV q 6 hrHave: 500 mg sterile powder
Per the medication label, reconstitution is required prior to administration.
You will need to know:A What is the diluent?B. How many _____ mL of diluent to add to the medication?C What is the final concentration _______ units/mL?D. How many _____ mL to administer for a 500 mg dose?
Medication label reads:Add 1.7 mL sterile water Final Concentration: 250 mg/mL
Step One: Add the liquid Per the medication label add 1.7 mL of Sterile Water to the medication bottle.
Step Two: Dosage Calculation
Answers:A. Diluent is sterile waterB. Add 1.7 mLC. Final concentration is 250 mg/mLD. Administer 2 mL for a 500 mg dose
× (O) Order
Volume (mL) = mL to administer(H) Have
× = 2
÷ × =
(O) 500 mg1 mL(V) mL to be administered
(H) 250 mg
500 mg 250 mg 1 mL 2 mL
91
Practice Problems
1. Order: Cefazolin 500 mg IVP Have: Cefazolin 1 g (gram) powder Per medication label: Add: 2mL sterile water or normal saline Final Concentration: 250mg/mL How many _____ mL will you administer for a correct dose?
2. Order: Zithromax 400 mg IV Have: Zithromax 500 mg powder Per medication label: Add: sterile water 4.8 mL Final Concentration: 100 mg/mL How many _____ mL will you administer for a correct dose?
3. Order: Versed 1 mg IVP Have: Versed 5 mg/mL Dilute for accurate dosage administration. Per medication guidelines, use normal saline for a diluent. A. How many ______ mL will you need to add to make a drug concentration of 5 mg/5 mL? B. How many _____ mL will you administer for a correct dose?
4. Order: Morphine 2 mg IVP Have: 10 mg/mL Diluent: Normal saline Dilute for accurate dosage control and increased patient comfort. A. How many ____ mL will you need to add for a final concentration of 1 mg/mL? B. How many _____ mL will you administer for a correct dose?
5. Order: Ampicillin 750 mg IV q 4 hr Have: Ampicillin 1 g powder (1 g = 1,000 mg) Add: 2mL sterile water Final Concentration: 500 mg/mL
Reconstitution and Dilution Practice problems
92
How many _____ mL will you administer for a correct dose? Practice Problems
6. Order: methylPREDNISolone 75 mg IV Have: methylPREDNISolone 125 mg vial Add: 2 mL of bacteriostatic water Final Concentration: 125 mg/2 mL
How many _____ mL will you administer for a correct dose?
7. Order: Solu-Medrol 100 mg IVP q 6 hr Have: 500 mg powder Add: 8 mL bacteriostatic water Final Concentration: 62.5 mg/mL How many _____ mL will you administer for a correct dose?
8. Order: Methicillin 1 g IV Have: Methicillin 1,000 mg powder (1,000 mg = 1 g) Add: 5 mL of sterile water Final Concentration: 1,000 mg/5 mL How many _____ mL will you administer for a correct dose? 9. Order: Zithromax 250 mg IV BID Have: Zithromax 1 g powder (1 g = 1,000 mg) Add: 9.8 mL sterile water Final Concentration: 100 mg/mL How many _____ mL will you administer for a correct dose?
10. Order: Penicillin G 1,000,000 units Have: 5,000.000 units Per the medication label, reconstitution is required prior to administration.
You will need to know:A. What is the diluent?B. How many _____ mL of diluent to add to the medication for a final concentration of 500,000 units/mL?C. How many _____ mL to administer for a 500 mg dose?
Instructions read:For a Final Concentration Add sterile normal saline250,000 units/mL 20 mL 500,000 units/mL 10 mL
Chapter 8
Reconstitution and Dilution Practice problems
93
Solutions
1. Administer 2 mL Order: Cefazolin 500 mg IV Have: Cefazolin 1 g (gram) powder Add: 2mL of diluent Final Concentration: 250 mg/mLStep One: Add 2 mL of diluent to powderStep Two: Dosage Calculation
2. Administer 4 mL Order: Zithromax 400 mg IV Have: Zithromax 500 mg in powder form Add: 4.8 mL of liquid Final Concentration: 100 mg/mLStep One: Add 4.8 mL to powderStep Two: Dosage Calculation
3. A. Add 4 mL B. Administer 1 mL. Order: Versed 1 mg IVP Have: Versed 5 mg/mLStep One: Dilute by adding 4 mL to Versed Goal: 1 mg of Versed for each mL of solution Have: Already have 1 mL in the Versed bottle (5 mg/mL) Add: 1 mL + ___ mL = 5 mL Drug Concentration: 5 mg/5 mL or Final concentration: 1 mg/mL Step Two: Dosage Calculation
Or
× =O
V mL to administerH
× =
÷ × =
500 mg1 mL 2 mL
250 mg
500 250 1 2 mL
× =O
V mL to administerH
× = 4400 mg
1 mL mL100 mg
× =O
V mL to administerH
× 5 = 15 mg
mL mL5 mg
Reconstitution and Dilution Practice solutions
94
Solutions
4. Add 9 mL Administer 2 mL Order: Morphine 2 mg IV push now Have: Morphine 10 mg/1 mLStep One: Dilute by adding 9 mL Goal: 1 mg of Morphine for each mL of solution (1 mg/1 mL) Have: 1 mL of solution in the bottle (10 mg/mL) Add: ___ mL plus 1 mL = 10 mL Drug Concentration: 10 mg/10 mL or Final concentration: 1 mg/mL Step Two: Dosage Calculation
Or
5. Administer 1.5 mL Order: Ampicillin 750 mg IV q4 hr Have: Ampicillin 1 g powder (1 g = 1,000 mg) Add: 2 mL sterile water Drug Concentration: 1,000 mg/2 mL or Final concentration: 500 mg/mL
Step One: Add 2 mL sterile waterStep Two: Dosage Calculation
Or
× = 11 mg
1 mL mL1 mg
× =O
V mL to administerH
× = 22 mg
1 mL mL1 mg
× = 22 mg
10 mL mL10 mg
× 2 = 1.5750 mg
mL mL1,000 mg
× =O
V mL to administerH
× = 1.5750 mg
1 mL mL500 mg
Chapter 8Reconstitution and Dilution
Practice solutions
95
Solutions
6. Administer 1.2 mL Order: methylPREDNISolone 75 mg IV Have: methylPREDNISolone 125 mg vial Add: 2 mL of bacteriostatic water Final Concentration: 125 mg/2 mLStep One: Add 2 mL bacteriostatic waterStep Two: Dosage Calculation
7. Administer 1.6 mL Order: Solu-Medrol 100 mg IVP q 6 hr Have: 500 mg powder Add: 8 mL bacteriostatic water Final Concentration: 62.5 mg/mLStep One: Add 8 mL bacteriostatic waterStep Two: Dosage Calculation
8. Administer 5 mL Order: Methicillin 1 g IVPB Have: Methicillin 1,000 mg powder (1 g = 1,000 mg) Add: 5 mL of sterile water Final Concentration: 1,000 mg/5 mLStep One: Add 5 mL sterile waterStep Two: Dosage Calculation
× =O
V mL to administerH
× 2 = 1.275 mg
mL mL125 mg
× =O
V mL to administerH
100 mg × 1 mL = 1.6 mL
62.5 mg
× =O
V mL to administerH
× 5 = 5 1,000 mg
mL mL1,000 mg
Reconstitution and Dilution Practice solutions
96
Solutions
9. Administer 2.5 mL Order: Zithromax 250 mg IV BID Have: Zithromax 1 g powder (1 g = 1,000 mg) Add: 9.8 mL sterile water Final Concentration: 100 mg/mL
Step One: Add 9.8 mL sterile waterStep Two: Dosage Calculation
10. A. Diluent is normal saline B. Add 10 mL C. Administer 2 mL Order: Penicillin G 1,000,000 units Have: 5,000.000 units Instructions read: For a Final Concentration Add Sterile Normal Saline 250,000 units/mL 20 mL 500,000 units/mL 10 mL Step One: Add 10 mL sterile water Final Concentration: 500,000 units/mLStep Two: Dosage calculation
× =O
V mL to administerH
×1 = 2.5 250 mg
mL mL100 mg
× =O
V mL to administerH
× 1 = 2 1,000,000 units
mL mL500,000 units
Chapter 8
Reconstitution and Dilution Practice solutions
97
Chapter 9
Formulas to Go
A Quick Reference: IV Dosage Calculation Formulas
98
Chapter 9
Formulas to GoIV Push Formula ( ) Order
(V) Volume mL to be administered( )OH Have
× =
Dimensional Analysis Formulaa b c d e
xb c d e f
= × × × ×
Ratio-Proportion Formula
Gravity System Formulas
Drops per Minute (DPM) formula:
×=
total volume to be infused (mL) drip factor (gtt/mL)drip rate (gtt/min)
total infusion time in minutes
To change a pump rate (mL/hr) to a gravity rate (gtt/min)
×
=infusion rate (mL/hr) drip factor (gtt/mL)
drip rate (gtt/min)60 minutes
IV Pump System Basic Formulas
1. Flow Rate (mL/hr)
2. Infusion Time
3. Infusion Volumes
known value known valueknown value desired value
=
=total volume to infuse (mL)
mL/hrtime in hours (hr)
=total volume to infuse (mL)
infusion timemL/hr
× =infusion rate (mL/hr) infusion time infusion volumes
99
Formulas to Go The Wrinkle Method Dosage Rate Formulas Dosage rates ending with min.
• mg/min • mcg/min • mcg/kg/min • units/min
These formulas ending in min are divided by 60 minutes. This is the basic formula: mg/min
mcg/min
mcg/kg/min
units/min
Dosage rates ending with hr. • mg/hr • units/hr • units/kg/hr
These formulas ending in hr are Not divided by 60 minutes. This is the basic formula: mg/hr
units/hr
units/kg/hr
mg ÷ mL ÷ 60 minutes = BedsideValue (BV)
mcg ÷ mL ÷ 60 minutes = BedsideValue (BV)
÷mcg ÷ mL ÷ 60 minutes kg = BedsideValue (BV)
units ÷ mL ÷ 60 minutes = BedsideValue (BV)
mg ÷ mL = BedsideValue (BV)
units ÷ mL = BedsideValue (BV)
÷units ÷ mL kg = BedsideValue (BV)
100
Chapter 9
Formulas to Go
The BedsideValue (BV)
The BedsideValue (BV) is calculated using one of the wrinkle method formulas. The (BV) is then used to calculate:
Flow Rate =
Dosage Rate =
= Order
mL/hr(BV)
= (mL/ hr) × (BV) dosage rate
Notes
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