Dosage Calculation using Dimensional Analysis Part 1 NURS

Dosage Calculation using Dimensional Analysis Part 1 NURS B 260

Conversions to Know Between systems: kg and lb. , gr. and mg. , oz. and grams, oz. and m. L. , in. and cm. , tsp and m. L. , tbsp. and m. L. , Within systems Lb. and oz. , m. L and L, mg and g. , tsp and tbsp. , quarts and gallon, pints and qts. , cup and oz. , pints and oz. , hours and minutes

Rounding Rules 0. 5 and above: Round Up 0. 49 and below: Round Down Drops/min: round to whole number Round at the end Follow rounding directions Answers must be rounded correctly for the answer to be graded as correct on dosage calculation exams

Other Key Concepts For answers less than one, a zero must precede the decimal point Example: 0. 5 mg. not. 5 mg. For answers that are whole numbers, write the number only. Example: 5 m. L. not 5. 0 m. L. These rules must be followed on exams

Steps to Follow Read each problem accurately. Determine pertinent information Determine what you need to solve for (x) and place to left of problem Correctly set up the problem. Start with the same unit of measure as (x) Cancel units of measure and reduce fractions as needed Perform checks and balances Solve the problem Round appropriately!!!!! Evaluate for logic and accuracy Transcribe answer accurately

Competency 1: Convert units of measure to another Your client weighs 124 pounds. Convert the weight to kg. and round nearest tenth. X kg = 1 kg x 124 lb 2. 2 lb 1 Answer: 56. 4 kg.

Competency 1 Practice 1. Your client weighs 15. 6 kg. Convert this to the nearest whole pound. 2. Your client’s incision is 5 inches long. Convert this to cm. State your answer in tenths. 3. The client is on a fluid restriction of 1500 m. L. per day How many ounces per day is this?

1. X lb. = 2. 2 lb. x 15. 6 kg. 1 2. X cm. = 2. 54 cm 1 in. 3. X oz. = 1 oz. X 30 m. L. x 5 in. 1 1500 m. L. 1 Answers: 34 pounds, 12. 7 cm. , 50 oz.

Conversions with 2 steps 1. The client is on a fluid restriction of 1. 5 L per day How many ounces per day is this? X oz. = 1 oz. x 1000 m. L x 1. 5 L 30 m. L. 1 L 1

Competency 2: Calculate the measurement of medication when the strength is not available The health care provider orders Pepcid 20 mg. p. o. twice per day. Pepcid 10 mg. tablets are available. How many tablets will you give for one dose?

X tabs. = 1 tab x 20 mg. 1 Answer: 2 tablets

Competency 2 Practice 1. Morphine Sulfate 2 mg. is ordered IV push now. The vial reads Morphine Sulfate 8 mg. /1 m. L. How many m. L. will you give? Answer: 0. 25 m. L 2. Potassium Chloride 20 m. Eq. p. o. is ordered now. The available liquid is 40 m. Eq. /15 m. L. How many m. L. will you give? Answer: 7. 5 m. L. 3. Atenolol 25 mg. is ordered p. o. once per day. Atenolol 50 mg. tablets are available. How many tablets will you give? Answer: ½ tablet

Competency 3: Calculate the number of doses available from bulk supply Amoxicillin suspension 100 mg. p. o. is ordered every 8 hrs. The label reads 125 mg. /5 m. L. The bottle contains 120 m. L. How many doses are in this bottle of suspension?

X dose = 1 dose x 125 mg. x 120 m. L 100 mg. 5 m. L. 1 Answer: 30 doses

Competency 3 practice Advil 400 mg. is ordered 3 times daily after oral surgery. The bottle contains 25 tablets that are 200 mg. each. How many full doses are in the bottle? X dose = 1 dose x 200 mg. x 25 tabs 400 mg. 1 tab 1 Answer: 12 doses

Competency 4: Reconstitute dry drugs with diluents and calculate the proper volume to be administered The order reads Ampicillin 375 mg. IM now. The 500 mg. vial is to be diluted with 1. 8 m. L. of normal saline to yield a concentration of 250 mg. / 1 m. L. How many m. L. will you give?

X m. L. = 1 m. L x 375 mg. 250 mg. 1 Answer: 1. 5 m. L.

Competency 4 Practice Medication: Penicillin G Sodium Diluent 4 m. L Units/m. L 1, 000 units/m. L Order: Penicillin G Sodium 2 million units IM. How many m. L would you administer?

X m. L = 1 m. L x 2, 000, 000 units 1 Answer: 2 m. L would be injected. Dilution would be with 4 m. L prior to drawing up the medication

Competency 5: Demonstrate on a syringe how to administer medication 1 m. L syringe (may be called TB syringe_ Marked with tenths and hundredths Insulin syringes (units for U 100 insulin) typically orange 100 unit syringes marked in 2 units 50 unit lo-dose syringes marked in 1 unit 3 m. L syringes Marked with 0. 1 m. L and 0. 05 m. L syringes Each line is 0. 2 m. L 10 m. L syringes and larger available for other uses (special IV lines, feeding tubes)

Competency 6: Calculate the Infusion Rate for IV fluids Key concepts Drops per minute for IV infusing by gravity Electronic IV pumps/Smart Pumps Macrodrip sets 10 -20 gtt per m. L Microdrip sets 60 gtt per m. L

Competency 6 Practice: Manual or Gravity IV infusions Your client is receive 1000 m. L of Normal Saline over 8 hours. The drop factor is 20 gtt. /m. L. Calculate the drip rate of this infusion in gtt. /min. X gtt = 20 gtt x 1000 m. L x 1 hr. Min 1 m. L 8 hours 60 min Answer: 42 gtt. /min

Competency 6 Practice: Electronic Pump IV infusions Your client is receive 1000 m. L of Normal Saline over 8 hours. At what rate should you set the IV pump (in m. L. /hr. )? X m. L. = 1000 m. L hr. 8 hrs. Answer: 125 m. L/hr.

Competency 6 Practice Order: 300 m. L of D 5 W over 12 hours. The drop factor is 60 gtt. /m. L. Calculatethe drip rate in gtt. /min. Order: Zosyn 2 g in 50 m. L. of NS IVPB to infuse via pump over 30 minutes. At what rate in m. L. /hr will you set the pump?

X gtt = 60 gtt. X 300 m. L x 1 hr. min 1 m. L. 12 hr. 60 min. Answer: 25 gtt. /min. X m. L = 50 m. L x 60 min. hr. 30 min 1 hr. Answer: 100 m. L/hr.

Competency 7: Calculate the running time of IV fluid The IV bag has 450 m. L remaining. It is infusing at 35 gtt/min via tubing that has a drop factor of 15 gtt/m. L. How many hours will it take for this volume of fluid to infuse? X hrs. = 1 hr. x 1 min 60 min. 35 gtt. x 15 gtt. x 450 m. L 1 m. L 3. 2 hours or 3 hours and 12 minutes 1

Competency 7 Practice 1. Calculate the gtt. per minute rate needed to infuse 250 m. L over 3 hours using IV tubing with a drop factor of 20 gtt. /m. L. 2. A 50 m. L. IVBP bag is infusing at 50 gtt. /min via tubing with a drop factor of 60 gtt. /m. L. How many minutes will it take the IV to infuse?

X gtt. = 20 gtt. x 250 m. L x 1 hr. min. 1 m. L 3 hrs. 60 min. Answer = 28 gtt. /min. X min. = 1 min. x 60 gtt. x 50 m. L. 50 gtt. 1 m. L 1 Answer = 60 min.

Competency 8: Calculate the amount of medication received when only a portion of the IV bag infused The confused client pulls out his IV after the infusion of only 150 m. L of an IV bag containing Vancocin 500 mg. in 200 m. L. of NS. How many mg. of Vancocin did the client receive? X mg. = 500 mg. X 150 m. L. 200 m. L 1 Answer: 375 mg.

Competency 8 practice 1. The client’s IV “infiltrates” after the infusion of only 100 m. L of an IV bag containing Vancocin 1 g. in 250 m. L. of NS. How many mg. of Vancocin did the client receive? 2. 1. 6 million units of Penicillin G K in 150 m. L of D 5 W is ordered to infuse over 45 minutes. The IV stops after 20 minutes. How many units of Penicillin remain in the bag? (Answer as whole number) 3. The infusion of Aminophylline 200 mg. in 500 m. L of D 5 W stopped after 350 m. L had infused. How many mg. of Aminophylline remain in the bag?

X mg. = 1000 mg. x 1 g 250 m. L. Answer: 400 mg. 100 m. L. 1 X units = 1, 600, 000 units x 20 min. 45 min. 1 Answer: 711, 111 units infused. 1, 600, 000 – 711, 111 = 888, 889 units X mg. = 200 mg. X 350 m. L 500 m. L 1 Answer: 140 mg. infused. 200 mg. – 140 mg. = 60 mg remaining