Medical Math Perform medical mathematical conversions common to the medical/health professions.

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 and cc are interchangeable) 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

Cubic centimeters = cc Millimeters = ml 1 oz = 30 cc or ml ml and cc are interchangeable. To find out how many cc a pt. drank or voided, you would multiply 30 X oz. Example: Ted drank 3 oz. of milk, how many cc did he drink? 30 X 3 = 90 cc or ml

Height Calculations The patient’s height is usually measured and documented in medical records as centimeters (cm) Nursing med math problems frequently require inches to be converted into centimeters 1 inch = 2.54 cm 1 cm = 0.393701 inches Example: A patient who is 67 inches is 170.2 cm (67 x 2.54 = 170.18, rounded to 170.2)

Temperature Calculations In medical settings, temperature is usually referred in degrees (°) Celsius. Subsequently, nursing med math problems frequently require conversions between Fahrenheit and Celsius Celsius to Fahrenheit: °C x 9/5 + 32 = °F Fahrenheit to Celsius: (°F – 32) x 5/9 = °C

Temperature Conversions Fahrenheit to Celsius: To convert from Fahrenheit to Celsius you must use the following formula: C=(F-32)5/9 Example: Mary’s temperature is 101F and your sister wants to know what that would be in C you would convert it: C=(101-32)5/9 (101-32= 69 X5=345/9=38.3 C

Temperature Conversion Celsius to Fahrenheit: In order to convert Celsius (C) to Fahrenheit (F) you must use the following formula: F= (C)9/5 + 32 For example: Your sister took your nephew to the Doctor and the nurse told her the babies temperature is 38C you tell her the babies temp is _ in Fahrenheit F=(38C) x9=342/5=68.4 + 32 =100.4F

Math Problems Answer each question on your own and then check answer with next slide. Adam voided 2 oz how many ml did he void? A nurse had a syringe fill with 10 cc of blood he used .5 ml for a lab test. How much was left? If a pt. drinks ¼ of a 12 oz soda, how many cc has she drank? If a pt. drank 3 oz of soda and 2 oz of milk, how many cc did she drink? Multiply 3 x 30 and 2 x 30 then add together = A male pt. is on intake and output. If he voided 240 cc how many oz. did he void. Divide 240 by 30 = A lab tech measures 30 ml of a urine sample in a 4 oz. container. How many more ml is needed to fill the container.

Volume and Mass Calculations Medications are often administered in units of milligrams (mg) and milliliters (mL) Nursing med math problems frequently require conversions between grams, milligrams, and micrograms, and liters, milliliters, and microliters Liters, milliliters, and microliters are used to express drug volume for dosing Grams, milligrams, and micrograms are used to drug mass for dosing

Check your answers: 60 ml 9.5 ml 90 cc 150 cc 8 oz. 90 ml To find out how many cc a pt. drank or voided, you would multiply 30 X oz. 9.5 ml 90 cc 150 cc 8 oz. 90 ml

Teaspoons and Tablespoons One teaspoon (tsp.) = 5 cc or 5 ml One tablespoon (tbs.) = 15 cc or 15 ml If a Dr. ordered a pt. to take 3 teaspoons of a medication how many cc would the pt. take? 3 x 5 = 15 cc or ml How many tablespoons is that? (15cc/ 15 tbs = 1tbs)

Check your math… Answer each question then check your answers on next slide. If a pt. was to take three teaspoons of Amoxil how many cc/ml would they take? You went to the Dr. and he gave you a prescription for Phenergan 25 mg/5cc. The Dr. wants you to take 25mg how many teaspoons would you take? The doctor ordered the nurse to give an infant 1½ teaspoon of Tylenol. How many cc would you give? Your mother is treating you for a cold and wants to give you Dimetapp. The instructions say to give 22.5 cc and your mother only has a tsp. How many tsp. would she give? On the previous question how many tbs would she give?

Answers… Check your answers 15 cc 3 tsp x 5cc = 15 cc 1 tsp 25 mg= 5cc 1 tsp = 5cc ½ tsp = 2.5cc 5cc + 2.5cc =7.5cc 4 ¼ tsp 5cc=1 tsp 22.5/5=4.25 or 4 ¼ tsp 1 ½ tbs 1 tbs = 15 cc 22.5/15= 1 ½ tbs

Weight Check it out…. 1 kg or (kilogram) x 2.2 lb (pounds)=lbs If an infant weights 4.09 kg their weight in lb is: 4.09kg x 2.2lb = 8.998 or 9lbs 1 lbs / 2.2 = kilograms If an infant weighs 10 lbs how much is that in kg? 10 lbs/2.2=4.54kg

Work the math… If an infant weighted 10 lbs at birth and the doctor needs to order medicine and needs to know how much the infant weights in Kg what would you tell him? The doctor orders you to give a toddler Amoxil 10 mgm/cc. The toddler weights 20lbs. The dosage is 10mgm/kg.How much would you give the toddler?

Answers…. 10lb x .454 kg = 4.54 kg 20lb x .454 kg = 9.08 Kg 10 mgm/kg/cc 10 x 9.08 =90 cc

Converting inches to centimeters One inch= 2.5 centimeters. If a person has a wound and it is 10 inches in diameter how many inches is it in cm? 10 X 2.5 = 25 cm. The wound is 25 cm in diameter. If a person has a 15 cm cut on their arm could they cover it with a 2 inch band aide? 15 / 2.5 = 6 inches no they would need three band aides.

Time Calculations In medical settings, military time is generally used rather than civilian (standard or conventional) time units This prevents confusion in the Medication Administration Record, or MAR and when documenting in the patient’s chart Use of military time minimizes risk of drug administration errors that may result from mix-ups between a.m. and p.m. hours

How to Calculate Time For a military time that's 1300 or larger, simply subtract 1200 to get the standard time. So for example if someone says "Meet me in room 202 at 1545," you'd just subtract 1200 from 1545 to get 3:45pm. If you want to convert standard time to military time, add 1200 to any time from 1:00pm to 11:00pm. So if you want to say 6:30pm in military lingo, add 1200 to 6:30 to get 1830.

Military Time