© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill 4-1 Math and Dosage Calculations for Health Care Third Edition Booth & Whaley Chapter

McGraw-Hill

4-1

© 2010 The McGraw-Hill Companies, Inc. All rights reserved

Math and Dosage Calculations for Health

Care Third EditionBooth & Whaley

Chapter 4: Equipment for Dosage Measurement

© 2010 The McGraw-Hill Companies, Inc. All rights reservedMcGraw-Hill

4-2

Learning Outcomes Identify equipment used to administer medication.

Indicate the appropriate equipment for delivering various types of medicine.

Measure medications using the calibrations on the equipment.

Describe the method of administration appropriate for each piece of measuring equipment.


4-3

Introduction

To prepare the correct dosage, it is important to be familiar with and use equipment properly.

Accurately read the dosage markings

Administration routes• Oral

• Parenteral – bypassing the digestive tract

• Topical / transdermal

• Drops, sprays, and mists

• Vaginal and rectal


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Oral Administration

Measuring devices are calibrated or marked at varying intervals.Calibrations are used to

• Measure the amount of liquid in the container

• Compare to desired dose

• Match physician’s order units• If container and order do not match, convert order to

units of measurement to be used.


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Oral Administration (cont.)

EquipmentMedicine cups

Droppers

Calibrated spoons

Oral syringes


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Medicine cupsMeasurements from all three systems

• Metric • Household • Apothecary

Meniscus • Curve in the surface of the liquid• Measure quantity at the bottom of the curve


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Rule 4 - 1Rule 4 - 1

Do not use medicine cups for doses less than 5 mL, even if the cup has calibrations smaller than 5 mL.

To ensure accuracy use• a dropper• a calibrated spoon• an oral syringe


4-8

Droppers

Uses Measure and

administer small amounts of oral liquid medication

Deliver medication to the eyes, ears, and nose

Oral pediatric doses

Units of measurement vary with dropper Packaged with product

Do not interchange droppers


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Calibrated Spoons

Used with pediatric and elderly patients

Administer medication directly into the mouth or into food or beverage


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Oral Syringes

Used for quantities less than 5 mL

Safety featuresEccentric tipsTinted

Not sterile


4-11

Oral Syringes (cont.)

Rule 4 – 2 Rule 4 – 2 1. Never attach a hypodermic needle to an oral

syringe.

2. Never inject an oral dose.

3. In emergencies, you may use a hypodermic syringe without a needle to measure and administer liquid oral doses, but never while its needle is attached.


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When a patient cannot take medication orally, medications can be administered through a tube to the stomach.

Types Nasogastric tube Nasal-small bowel tube PEG tube Jejunostomy tube


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Error Alert!

Utensil used must provide the calibration needed to accurately measure the dose.

ExampleExample

Which would you select to administer ½ tsp. of a liquid medication?


4-14

Practice

Determine if the statements below are true.

1. You may use a hypodermic syringe with a needle to measure liquid for oral administration.

2. Oral and hypodermic syringes are identical in appearance.

3. Measuring spoons used for baking are acceptable for measuring liquid medications.

False

False

True


4-15

Practice

4. Oral medication comes in a bottle labeled 200 mg/5 cc. The dose to be administered is 600 mg. Which of the following is the correct dose?

a) 1 tspb) 2 tspc) 1 tbspd) 2 tbsp

= 15 mL


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Hypodermic Syringes

Parenteral administration

Administer medications by injection Intravenous (IV) Intramuscular (IM) Intradermal (ID) Subcutaneous (Sub-Q)


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Standard Syringes

Calibrated in milliliters (mL)Metric system is used most

oftenMay be marked in minims

Allow for measurement of small doses

3-mL syringe most common


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Standard Syringes (cont.)

Zero calibration – edge of barrel near needle

Leading ring - tip of plunger closest to needle

Trailing ring – ring farthest from needle

Click to view syringe


4-19

Trailing RingLeading Ring

Hypodermic Syringes (cont.)

Plunger

Leading RingTrailing Ring

Leading Ring

Barrel

Syringe hub

Needle


Plunger


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Safety Syringes

Same components as standard syringe

Safety shields protect needle

Reduce the chance of needlestick injury

3 mL syringe with retractable needle


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Prefilled Syringes

A single, standard dose of medication Use once and discard

Usually marked in tenths of a mL

Measure the dose carefully

Discard any excess medication

prior to injection


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Prefilled Syringes

Rule 4 - 3Rule 4 - 3When using a prefilled syringe, always examine the markings to determine whether the syringe is calibrated in milliliters or milligrams and calculate the dose accordingly.


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Insulin Syringes (cont.)

Used only to measure and administer insulin

Calibrated in units Insulin doses order in units U-100 insulin most common form

• 100 units of insulin per 1 mL

Syringes available in 30, 50, and 100 Unit capacities


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100 Unit Insulin Syringe

50 Unit Insulin Syringe


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Comparison of insulin syringes:

50 unitsyringe

100 unitsyringe


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Rule 4 - 4Rule 4 - 4Never use any type of syringe other than an insulin syringe to measure and administer insulin.


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Tuberculin Syringes

Used for doses less than 1 mLCalibrated in

hundredths of a mL

Requires careful measurement

Examples:PPD skin testVaccinesHeparinPediatric

medicinesAllergen extracts


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Tuberculin Syringes (cont.)

1 mL Tuberculin Syringe

0.5 mL Tuberculin Syringe


4-29

Tuberculin Syringes (cont.)

Comparison of tuberculin syringes:

0.5 mL syringe

1 mL syringe


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Syringes for Established IV Lines

Used to administer medication and fluids directly into a patient’s vein

Uses the injection port of an IV line

Advantages Eliminates repeated punctures for the patient Decreased risk of needlestick injuries Compatible drugs can be administered together Enables drug delivery on a periodic basis Enables dilution of the medication


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Syringes for Established IV Lines (cont.)

Plastic injection tip

Injection port on IV line


4-32

Large-Capacity Syringes

Not all medication can be delivered in doses of 3 mL or less.

Syringes with 5 mL, 6 mL, 12 mL are available Volume is measured in milliliters but calibrations

between may vary.

Look carefully at the marks to measure an accurate amount of medication.


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Large-Capacity Syringes (cont.)

10 mL syringe


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Error Alert!

Pay close attention to the calibration of any syringe you use.

Check the marks carefully.

Always align the leading ring with calibration.


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Ampules, Vials, and Cartridges

Cartridge Vial

Ampule


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Cartridges

Prefilled container shaped like a syringe barrel

One dose of medication

Fits a reusable syringe

ExamplesTubex®

Carpuject®


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Ampule

Sealed container holding one dose of medication

Snaps open

Use a standard syringe to withdraw the medication


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Vials

Container covered with a rubber stopper

Contain one or more doses of medication

Either liquid or powder form of medication that must be reconstituted


4-39

Preparing the Syringe

Rule 4 - 5Rule 4 - 5 In most circumstances, the person who prepares a syringe for injection should deliver the injection.

Exceptions include:1. Pharmacy technicians who prefill syringes for

nurses, medical assistants, or patients2. Nurses or medical assistants preparing a syringe

for a physician3. Health-care workers teaching a patient to

administer his or her own medication


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Needle Gauge and Length

Choose appropriate needle for injectionGauge

• Interior diameter

• Smaller gauges correspond to larger diameters

• Use larger needles for more viscous drugs and deeper injections


4-41

Needle choice (cont.)

Length• The injection site determines length.

• Length must be long enough to reach the desired area of tissue.

• Length must not be so long that it penetrates beyond the desired area.

Needle Gauge and Length (cont.)


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Needle Gauge and Length (cont.)

Type of Injection Needle GaugeLength (inches)

for Adults

Intradermal 25 – 26

Subcutaneous 23 – 27

Intramuscular 18 – 23 1 – 2

85

83

85

21


4-43

Practice

Identify the parts of this syringe:

Barrel

Syringe hub

Needle


PlungerA. B.

C.D.

E.

F.


4-44

Practice

You have an order to administer 1.5 mL of a medication. It comes in a 3 mL prefilled syringe. What should you do?

ANSWER Carefully check the calibration and discard the excess medication prior to giving the injection. In this case, you would discard 1.5 mL medication. You should NEVER attempt to inject the correct dose without removing the excess medication first.


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Topical Medications

Gels, creams, ointments, and pastes

Apply directly to the skinUse a glove, tongue blade, or cotton-tipped

applicator

Avoid contact your own skin• Wear non-sterile gloves

to apply or remove


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Transdermal Medications

Form of topical medication absorbed through the skin.

Use a self-adhesive patch. Place patch on clean, dry, hairless skin with no rash

or irritation and with good circulation. Rotate placement sites. Remove older patches and dispose of them

properly. Mark each new patch with your initials, the date, and

the time.


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Transdermal Medications (cont.)

Maintain a consistent level of medication in the blood.

Bypass GI system.

Uses Cardiovascular drugs Hormones Allergy medications Pain medications


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Drops, Sprays, and Mists

Drops Instillations Nose, eyes, and ears Use the equipment that comes with the drug to

administer the medication.

Mists Inhaled by patient Vaporizers – water used to create mist Nebulizers and metered dose inhalers (MDIs)

Sprays Nose and throat


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Vaginal and Rectal Medications

Rectal Suppositories

Enemas for liquid forms of medication

Creams and foams

Vaginal Suppositories

Tablets

Douches for liquid forms of medication

Creams and foams


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Apply Your Knowledge

Which type of delivery device is used to administer medication to the eyes and ears?

ANSWER Dropper

What instructions should you provide a patient who is starting a new medication delivered by a transdermal patch?

ANSWER The patch should be put on clean, dry, hairless skin with no rash or irritation. Placement sites should be rotated. Older patches should be removed and disposes of properly.


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Apply your Knowledge

What kind of syringe is used to deliver vaccinations?

ANSWER Tuberculin


4-52

Apply your Knowledge

How many mL are indicated on this syringe?

ANSWER 1.6 mL


4-53

End of Chapter 4

Nothing will work unless you do.

~Maya Angelou

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© 2010 The McGraw-Hill Companies, Inc. All rights reserved McGraw-Hill 4-1 Math and Dosage Calculations for Health Care Third Edition Booth & Whaley Chapter