Medication Basic Math

Logical Life Center

Medication Training

Objectives

• Learn the formula for IV Flow Rate, Infusion Time, and Total Volume

• Discuss Formula from the video

• Learn the common conversion factors

• Learn the common medication errors

When administering IV

• Know:– Flow rate, infusion time, and total volume– Use one of the following equations:

• flow rate (mL/hr) = total volume (mL) ÷ infusion time (hr)• infusion time (hr) = total volume (mL) ÷ flow rate (mL/hr)• total volume (mL) = flow rate (mL/hr) × infusion time (hr)

• For example, if you must administer 1 L (1,000 mL) of fluid over 4 hours, use the first formula to calculate the flow rate, like so:

• flow rate (mL/hr) = total volume (mL) ÷ infusion time (hr)• flow rate (mL/hr) = 1,000 ÷ 4• flow rate (mL/hr) = 250• The flow rate is 250 mL/hr.

Common Conversions

• Common Conversion Factors in Medical Dosage Calculations• As a healthcare professional, you have to convert patient weights, fluid

volumes, medication weights, and more. Conversion math isn’t hard to do as long as you know the basic conversion factors. Here are the most useful ones:

• Converting lb to kg and kg to lb– lb = kg × 2.2– kg = lb ÷ 2.2

• Converting mL to L and L to mL– mL = L × 1,000– L = mL ÷ 1,000

• Converting mg to g, g to mg, mg to mcg, and mcg to mg– mg = g × 1,000– g = mg ÷ 1,000– mcg = mg × 1,000– mg = mcg ÷ 1,000

Unacceptable Errors

• Making sure that you correctly calculate a dose doesn’t matter much if the medication itself is incorrect or the dosing instructions are unclear. Some abbreviations in prescriptions are unacceptable because they cause ambiguity and confusion.

Unacceptable Errors

Abbreviation

Mistaken Meanings Better Choice

DC or D/C

Does it mean “discontinue” or “discharge”?

Write discontinue or discharge.

HSDoes it mean “half-strength” or “at bedtime”?

Write at bedtime or a designated time.Also write out the specific dosing strength and/or quantity

QD

Does it mean “every day” or “right eye”? QD looks like OD, which means “right eye.” (OS means “left eye.”)

Write every day.

QODDoes it mean “every other day” or “daily”?

Write every other day or daily, according to patient’s needs.

MSO4Does it mean “magnesium sulfate” or “morphine sulfate”?

Write magnesium sulfate or morphine sulfate.

Unacceptable Errors

U or IUDoes it mean “unit” or “zero”? Could it be mistaken for “0” or “10”?

Write units.

IV

Does it mean “intravenous,” “international units,” or “4”?

IV is an acceptable abbreviation for “intravenous,” but the doc could write international units or intravenous to be clearer.Or “4”

SQ or SC

Does it mean “subcutaneous” or could it be mistaken for “5Q” (“5 every”)?

Write Subq, subcut, subcutaneous, or 5 every.

TIWDoes it mean “twice a week” or “three times a week” (the real meaning)?

Write twice a week or three times a week.

cc

Does it mean “cubic centimeter” or “milliliter”? Could it be mistaken for “00”?

Write milliliter or mL.

Ug or gDoes it mean “microgram” or “Ugh”? Could it be mistaken for mg?

Write microgram or mcg.

ODDoes it mean “once daily” or “right eye”?

Write once daily or right eye.