Calculations Chapter 12

Drip, drip, drip, drip……..“Someone call a plumber!”

Drip Rates & Dimensional Analysis

This process can be used for any multistep conversions. As long as you use the correct conversion factor and

the units cancel properly you will get the correct answer.

Basics of Dimensional Analysis

• Can be used with any units.• First determine what the question is asking.• What are the units of your answer?• Units from the numerator can cancel with the

same units in the denominator.• After only the desired unites remain:– Multiply Numerators– Multiply denominators– Reduce

An Example:Consider the question:Calculate the drops per minute of an infusion 1.5gm in 500ml D5W, infused at 50mg/minute, with a drip factor of 20gtts/ml.

1. Write down all of the ratios from the problem.2. Determine what the question is asking.3. What are the units of the answer?

• What are the units of the answer?

• So, Let’s start with a conversion that uses drops in the numerator.

• Next, we need to cancel mls

•Now, We need to get ride of gms.

• Now, to get rid of the mg

• Remember to check that all of the units cancel.

• Now Multiply

• And Reduce

Chapter 12: Calculation of Medications for Intravenous Uses

• Get out math chapter 12.• Some scratch/blank paper.• Your calculator.

• A physician orders 1 L of D-5-W to be infused over 8 hours using a drop factor of 15 drops/mL. What is the drip rate for this infusion?

• What is the rate of milliliters per hour? • What is the rate of milliliters per minute?

• A physician orders a continuous infusion of D-5-NS to infiltrate for 24 hours. The drop factor is 15 gtts/mL and the flow rate is 35 mL/hr. How many 1-L containers of the fluids would be needed to fulfill these orders?

• A container of 500 mL of D-5-W is infusing at the rate of 30 drops per minute using a drop factor of 20 drops/mL. How many milliliters per hour will the patient receive?

• How long will it take for the fluids to infuse? How many milliliters per minute should the patient receive?

• A physician orders VANCOMYCIN 1 g to infuse over 12 hours in 750 mL of fluids. The drop factor is 15 drops/mL. How many milliliters per minute will the patient receive?

• How many drops per minute should the patient receive? • How many milligrams of vancomycin per hour will the patient

receive? • How many micrograms of vancomycin will the patient receive an

hour?

• An order for PIPERACILLIN 1.5 g in 250 mL NS q6h is sent to the pharmacy. The medication is to infuse over 45 minutes. How many milliliters per hour would the patient receive?

• What would be the most appropriate drop factor for this infusion? • How many milliliters per minute should the patient receive? • How many drops per minute should the patient receive with the

set chosen?

• A physician orders HEPARIN SODIUM 500 U/hr to be administered in 250 mL of D-5-W. HEPARIN 10,000 U have been added to the fluids. What is the volume of fluids that the person should receive each hour?

• If the infusion set is 10 gtts/mL, what should be the flow rate? • How long will this container of fluids last?

• A physician orders CEFAZOLIN 0.5 g in 50 mL NS to be infused over 45 minutes. How many milliliters per hour should the fluids infuse?

• If the drop factor is 25 drops/mL, what is the flow rate? • How many milligrams of CEFAZOLIN will the patient receive in 10

minutes?

• A heart patient has an order for NITROGLYCERIN 10 mcg/min. D-5-W 100 mL contains NITROGLYCERIN 20 mg. How many milliliters per hour should the patient receive?

• How many milliliters per minute should the patient receive? • If the drop factor is 10 drops/mL what is the flow rate? • How long will the medication take to infuse? • How many milligrams of NITROGLYCERIN should the patient

receive each hour?

• Administer 80ml/hr via a set calibrated at 15gtt/ml.

• 1400ml D5W with 20mEq KCl/L has been ordered to run over 12 hours. Set is calibrated at 15gtt/ml.

• A patient is to receive 1400ml of 0.9% NaCl in 14 hours using a 15gtt/ml set.

• An IV of 400ml was ordered to infuse in 7 hours using 20gtt/ml tubing. With 2 hours remaining you discover only 100ml left in the bag. At what rate will you need to reset the rate of flow to ensure proper infusion?

• An IV of 1200ml was scheduled to run in 10 hours using 15gtt/ml tubing. After 4 hours only 140ml have infused. Recalculate the rate for the remaining solution.

• An IV of 1000ml was ordered to infuse in 20 hours. With 3 hours of infusion time left you discover that 800ml have infused. The tubing set used is 10gtt/ml. Recalculate the drip rate.

• An IV of 1200ml was ordered to run over 5 hours with the set calibrated at 20gtt/ml. After 2 hours you notice that 600ml have infused. Recalculate the drip rate.

• An IV of 1000ml was ordered to infuse in 8 hours using 10gtt/ml tubing. With 2 hours remaining, you discover that only 200ml is left in the bag. At what rate will you need to reset the rate of flow to ensure proper infusion?

• An IV of 1200ml was scheduled to run in 12 hours using 15gtt/ml tubing. After 8 hours, only 600ml have infused. Recalculate the rate for the remaining solution.