Math: Basic Tutorials : Infusion Rates for Intravenous Piggyback (IVPB) Bags

Infusion Rates for Intravenous Piggyback (IVPB) Bags

Intravenous Piggyback (IVPB) is a method of administering secondary medications through an existing IV line, typically over a short period. These medications are delivered intermittently, often diluted in a small IV bag and infused at a controlled rate. Proper calculation of IVPB infusion rates is crucial to ensure the correct medication dose is administered within the prescribed time frame.

This section covers the principles of IVPB administration, with examples on how to calculate flow and dosage rates, ensuring safe and accurate medication delivery.

Intravenous (IV) Piggyback Solutions

Clients can receive a second infusion using an IV piggyback line hung alongside the first. Usually, a secondary IV interrupts the administration of the primary IV medication. The primary IV resumes after the secondary IV has finished. Since the two lines do not mix, we only need to calculate the flow and dosage rates for the secondary line.

Examples

Click on the titles below to view each example.

Example 1

Example 1:
An IVPB is infusing at $120 m L / h$ . The concentration is 50 mg in 100 mL of NS. What is the dosage rate in mg/min?
There are a few things we need to convert to get $120 m L / h$ to the dosage rate of mg/min. First, we can infuse the concentration of 50 mg in 100 mL of NS.	$\frac{120 m L}{1 h} \times \frac{50 m g}{100 m L} = \frac{60 m g}{1 h}$
Next, we need to convert hours into minutes	$\frac{60 m g}{1 h} \times \frac{1 h}{60 m g} = 1 m g / m i n$
Solution:	The dosage rate for this IV piggyback is 1 mg/min.

Example 2

Example 2:
Your client is a 125 lb adult. An order for Tagamet 5mg/kg in 50 ml D5W IVPB to be infused in 20 minutes. Use the label below with the drop factor 10 gtts/mL.
a. How many mL of Tagamet will you add to the IV fluid?
First, we have to find the weight of the client in kg.	$125 l b = \frac{1 k g}{2.2 l b} = 56.82 k g$
The order for Tagamet is for 5 mg/kg.	$56.82 k g \times \frac{5 m g}{1 k g} = 284.1 m g$
Thus the order should be 284.1 mg. Next, the Tagament strength from the label is 300mg/2mL.	$284.1 m g \times \frac{2 m L}{300 m g} = 1.9 m L$
Solution:	1.9 mL should be added to the IV.
b. What will be your flow rate in gtts/min?
First, we convert Tagamet in 50 mL using the drop factor 10 gtt/mL.	$50 m L \times \frac{10 g t t}{1 m L} = 500 g t t$
Then we find the flow rate by dividing the time of 20 minutes.	$\frac{500 g t t}{20 m i n} = 25 g t t / m i n$
Solution:	The flow rate will be 25gtt/min
c. In mL/h?
Converting 50 mL in 20 minutes to mL/h	$\frac{50 m L}{20 m i n} \times \frac{60 m i n}{1 h} = 50 m L / h$
Solution:	The flow rate will be 15mL/h

Example 3

Example 3:
An order of morphine sulfate 200 mg IVPB in NS 1000 mL to be infused at a rate of 20 mcg/kg/h stat. The client weighs 134 kg.
a. How many mg/h of this narcotic analgesic will the client receive?
First, we calculate the mcg required for a client weighing 134 kg at the infusion rate of 20 mcg/kg.	$134 k g \times \frac{20 m c g}{1 k g} = 268 m c g$
Now we convert the 268 mcg/h to mg/h.	$\frac{268 m c g}{1 h} \times \frac{1 m c g}{1000 m c g} = 2.68 m g / h$
Solution:	The client will receive 2.68 mg/h IVPB immediately.
b. How many mL/h of the solution will the client receive?
The order of 200 mg IVPB in NS 1000 mL can be used with the 2.68 mg/h to calculate the mL/h to be administered.	$\frac{1000 m L}{200 m g} \times \frac{2.68 m g}{1 h} = 13.4 m L / h$
Solution:	The client will receive 13.4 mL/h of morphine sulfate.

Practice

IVPB Practice Questions

Last Updated: Jun 25, 2025 4:00 PM
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