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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


× =(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


× ( = 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


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


IV Push Practice solutions

8


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


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

×=



× = 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

×=



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)


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


infusion timemL/hr

3. Calculate Infusion Volumes Order: Normal Saline 150 mL/hr for 3 hours



= 8 1,000 (mL)

hours125 mL/hr


× 3 = 450 150 (mL/hr) (hr) mL

IV Pump System Examples of Basic IV Infusion Formulas

18

Calculate Flow Rate (mL/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: _____


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: _____



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: _____



Chapter 2


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)= =



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


infusion timemL/hr

Chapter 2


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



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 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 =


÷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)


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 =


÷ ÷ =

÷ ÷ =

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 Three: Calculate both

Flow Rate =

Dosage Rate =


× =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 Three: Calculate both Flow Rate = Dosage Rate =


× = 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 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)



Flow Rate =

Dosage Rate =


÷ =

÷ =

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)



Flow Rate =

Dosage Rate =


÷ ÷ =

÷ ÷ =

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







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


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: _____


Chapter 5


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: _____



54

Chapter 5


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


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


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 =


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


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)



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


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


BV

Dosage Rate mL/hr BV= ×


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.


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


100 mg mL BV÷100 = 1

8mL/hr

1= 8


BV

Dosage Rate mL/hr BV= × mg8 ×1 = 8

2mL/hr

1= 2


BV

Dosage Rate mL/hr BV= × mg2 ×1 = 2

Chapter 6


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


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? _____



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


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


BV

Dosage Rate mL/hr BV= × mcg38 × 0.13 = 5


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


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


BV


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


BV


Chapter 6


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


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


BV

Dosage Rate mL/hr BV= × mcg79 ×1.89 = 149.3


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



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


BV


1mL/hr

0.53= 2


BV


Chapter 6


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


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


BV

Dosage Rate mL/hr BV= × 13× 0.04 = 0.5 mcg


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


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


BV


5mL/hr

2.13= 2


BV

Dosage Rate mL/hr BV= × mcg2 × 2.13 = 4.26

Chapter 6


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.


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


BV

Dosage Rate mL/hr BV= × 10 1 10 units× =

25, 000 units mL 100 BV÷ 250 =

800 mL/hr

100= 8


BV

Dosage Rate mL/hr BV= × 100 units8 × = 800


66

Chapter 6


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


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


BV16

mL/hr3.33

= 5


67


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


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


BV


mcg15 × 0.08 = 1.2

1.2 mcg mL/hr

0.08= 15

mcg10 × 0.08 = 0.08

68

Chapter 6


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


Dosage rate at 19 mL/hr

200 units 250 mL 60min 0.013 BV÷ ÷ =

0.3 unitsmL/hr

0.013 = 23


BV

Dosage Rate mL/hr BV= × units23× 0.013 = 0.3

19 units× 0.013 = 0.25

69


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


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


BV

5 mcg/minmL/hr

0.26 BV= 19

Dosage Rate mL/hr BV= × 50 × 0.26 = 13 mcg

70

Chapter 6


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.


30 mgmcg =

1,000 mcg1 1 mg

× mcg= 30, 000

30,000 mcg mL 60 min BV÷ 500 ÷ = 1


BV100

mL/hr3.33

= 30

Dosage Rate mL/hr BV= × mcg75 ×1 = 75

100 mg mL BV÷100 = 1

1mL/hr

1= 1


BV

Dosage Rate mL/hr BV= × mg1×1 = 1

71


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


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)



20 units 100 mL 60min 0.003 BV÷ ÷ =


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


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


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


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=° °


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


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


× =(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


× = 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


× = 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


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


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:

×=



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

=




infusion timemL/hr


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






units ÷ mL = 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

iv dosage calculations - amazon s3 · • the drip rate (gtt/min) is how fast or slow the...

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