Nursing: Dosage Calculation Conversions and Formulas Flashcards

Question 1

Define Kilograms and Pounds (1 kg = 2.2 lb).

Accepted Answer

The weight conversion behind every weight-based order: one kilogram equals 2.2 pounds, so a weight in pounds is divided by 2.2 to give kilograms.

Question 2

Define Grams and Milligrams (1 g = 1,000 mg).

Accepted Answer

The metric step between the two units most tablet labels use: one gram contains 1,000 milligrams, so converting moves the decimal point three places.

Question 3

Define Milligrams and Micrograms (1 mg = 1,000 mcg).

Accepted Answer

The conversion used for small, potent doses: one milligram contains 1,000 micrograms, written mcg. Mixing the two up produces a thousandfold dosing error.

Question 4

Define Liters and Milliliters (1 L = 1,000 mL).

Accepted Answer

The volume conversion for IV fluids and intake: one liter holds 1,000 milliliters. IV bags are labelled in either unit, and rates are always set in millilitres.

Question 5

Define Teaspoon (tsp = 5 mL).

Accepted Answer

The household volume measure equal to 5 millilitres, used when converting oral liquid orders for patients and families who measure at home.

Question 6

Define Tablespoon (tbsp = 15 mL).

Accepted Answer

The household volume measure equal to 15 millilitres, or three teaspoons. Confusing it with a teaspoon triples the dose, a known home-dosing error.

Question 7

Define Fluid Ounce (1 oz = 30 mL).

Accepted Answer

The household volume unit counted as 30 millilitres in nursing calculations, used most often for recording oral intake from cups, cartons and bottles.

Question 8

Define Cup (1 cup = 240 mL).

Accepted Answer

The household measure equal to 8 fluid ounces, counted as 240 millilitres when calculating oral intake or converting diet orders.

Question 9

Define Desired Over Have (D/H × Q).

Accepted Answer

The basic dose formula: the dose ordered (desired) divided by the dose on hand (have), multiplied by the quantity that dose comes in, such as one tablet or 5 mL.

Question 10

Define Dimensional Analysis.

Accepted Answer

A calculation method that chains conversion factors as fractions so unwanted units cancel top and bottom, leaving only the unit the answer needs.

Question 11

Define Ratio and Proportion.

Accepted Answer

A dosage method that sets the known strength equal to the unknown dose as two equal ratios, then cross-multiplies to solve for the missing quantity.

Question 12

Define Conversion Factor.

Accepted Answer

A fraction equal to one, written with the same quantity in two units, such as 1,000 mg over 1 g, that changes a value's unit without changing its size.

Question 13

Define Concentration (Dose on Hand).

Accepted Answer

The amount of drug in a set volume of liquid, printed on the label as a dose per volume, such as 100 mg per 5 mL or 1,000 units per mL.

Question 14

Define IV Flow Rate (mL/hr).

Accepted Answer

The volume of IV fluid given each hour, found by dividing the total volume in millilitres by the infusion time in hours; it is the number entered into a pump.

Question 15

Define IV Drip Rate (gtt/min).

Accepted Answer

The number of drops per minute for gravity tubing, found by multiplying the volume in millilitres by the drop factor and dividing by the time in minutes.

Question 16

Define Drop Factor (gtt/mL).

Accepted Answer

The number of drops that make one millilitre for a particular IV tubing set, printed on the tubing package and needed for every gravity drip-rate calculation.

Question 17

Define Macrodrip Tubing.

Accepted Answer

IV tubing that forms large drops, with a drop factor of 10, 15 or 20 gtt/mL, used for routine adult infusions and fast fluid replacement.

Question 18

Define Microdrip Tubing.

Accepted Answer

IV tubing that forms small drops at 60 gtt/mL, used for small volumes and precise rates; with it, drops per minute equal millilitres per hour.

Question 19

Define Infusion Time.

Accepted Answer

How long an IV volume takes to run, found by dividing the total volume by the hourly rate; the result is in hours and is often converted to a clock time.

Question 20

Define Weight-Based Dosing (mg/kg).

Accepted Answer

Prescribing a drug as an amount per kilogram of body weight, so the single dose equals the ordered amount multiplied by the patient's weight in kilograms.

Question 21

Define Safe Dose Range.

Accepted Answer

The minimum and maximum daily or single dose recommended for a patient's weight, which a nurse calculates and compares with the order before giving a pediatric medication.

Question 22

Define Units (Heparin and Insulin).

Accepted Answer

A measure of a drug's biological activity rather than its weight, used for heparin, insulin and some vitamins; it is not converted to milligrams.

Question 23

Define Leading Zero.

Accepted Answer

A zero placed before a decimal point in a dose under one, as in 0.5 mg, so a faint or missed decimal point cannot be misread as a whole number.

Question 24

Define Trailing Zero.

Accepted Answer

A zero written after a decimal point in a whole-number dose, as in 2.0 mg. It is banned because a missed decimal point makes the dose ten times larger.

Question 25

Define The Joint Commission Do Not Use List.

Accepted Answer

The Joint Commission's official list of medication abbreviations banned in US clinical documentation: U, IU, QD, QOD, trailing zeros, missing leading zeros, MS, MSO4 and MgSO4.

Question 26

Define mcg (Microgram).

Accepted Answer

The safe abbreviation for microgram. The Greek-letter form µg is on the error-prone list because a handwritten µ can be read as m, giving a thousandfold overdose.

Question 27

Define PO (By Mouth).

Accepted Answer

From the Latin per os, the abbreviation for giving a medication orally, swallowed as a tablet, capsule or liquid.

Question 28

Define NPO (Nothing by Mouth).

Accepted Answer

From the Latin nil per os, an order that the patient takes no food or fluids orally, often before surgery or when swallowing is unsafe.

Question 29

Define Subcut (Subcutaneous).

Accepted Answer

The recommended way to write the subcutaneous route, into fatty tissue under the skin. ISMP lists SC and SQ as error-prone because they can be misread.

Question 30

Define BID (Twice a Day).

Accepted Answer

From the Latin bis in die, a timing abbreviation for a medication given two times a day, usually about 12 hours apart according to facility schedule.

Question 31

Define TID (Three Times a Day).

Accepted Answer

From the Latin ter in die, a timing abbreviation for a medication given three times a day, commonly scheduled with meals or about every 8 hours.

Question 32

Define PRN (As Needed).

Accepted Answer

From the Latin pro re nata, an order for a medication given only when the patient needs it, with a stated reason and a minimum interval between doses.

Question 33

Define STAT (Immediately).

Accepted Answer

From the Latin statim, an order to give a one-time dose immediately, usually expected within minutes of the order being written.

Question 34

Define QD and QOD (Do Not Use).

Accepted Answer

Banned abbreviations for daily and every other day. The period after Q can be read as I, turning daily into four times a day; write daily and every other day.