Intermediate IV Therapy and Flow Rate Problems/ Learn
Jean Montgomery, Austin Community College

Examples

• Example 1
• Example 2
• Example 3
• Example 4
• Example 5
• Example 6
• Example 7
• Example 8
• Example 9

The doctor writes and order for NS 1000mL to infuse over 6 hours.

Equipment needed:

0.9% Normal Saline (type of solution) 1000mL bag (volume to be infused)
Primary IV Tubing (Macrodrip tubing 10 gtt/mL)

 The doctor's orders restated. Type of IV Solution - Normal Saline (0.9%) Amount of IV Fluid to be Administered - 1000mL The Period of time the fluid is to be administered - over 6 hours.
 1000mL 6hr = 166.67 mL hr =167 mL hr

Every hour for the next 6 hours the client will receive 167 mL of fluid.

Electronic pumps are desirable for more accurate monitoring of IV fluid and medication administration. The primary rate of infusion would be programmed into the electronic pump or EID (Electronic Infusion Device) at 167 mL/hr. This increment of time (mL/hr) is one of the most commonly used forms of flow rate that is used in the management of IV therapy. Remember to follow the rules for rounding when the volume amount is a fraction.

Safety Alert: Healthcare providers should check the IV infusion hourly on adult clients and more frequently with pediatric clients to ensure that the client is tolerating the infusion without problems and to verify the appropriate volume is being administered.

What would happen in a remote area if there were no electric pumps available (EIDs) to monitor IV therapy?
It will be nearly impossible to accurately manage an IV infusion using a flow rate of mL/hr. It would be time consuming and inappropriate to sit at the bedside for one entire hour and ensure that the client received the appropriate fluid amount.

Instead, the healthcare provider monitors a smaller increment of time (15 seconds) and the flow rate delivered by the calibration of the IV set to determine the rate of infusion of the IV fluids. To calculate this answer we need to know the speed of delivery of the IV tubing (the calibration or the drop factor). To help demonstrate this, we will continue to use the same example.

The doctor writes and order for NS 1000mL to infuse over 6 hours.

Equipment needed:
0.9% Normal Saline (type of solution) 1000mL bag (volume to be infused)
rimary IV Tubing (Macrodrip tubing 10 gtt/mL)

We have already calculated that the rate is 167mL/hr. We also know that our primary tubing is calibrated into 10 gtt/mL, which is also referred to as the drop factor.
The inner diameter of the IV tubing (calibration) determines delivery speed (gtt/min)

We can use the drop factor 10 gtt/1 mL and then use the rate in mL/hr to compute how many gtts/min should be delivered.

We could further divided by 4 to determine how many drops would fall in 15 seconds. You could then use your second hand on your watch to count 7 drops that should drip in 15 seconds. This is much easier to manually monitor at the bedside if there is no electronic pump available.

Safety Alert: Healthcare providers should always compute gtt/min when using a dial a flow meter and they should monitor for the correct amount of dripping activity. This gives added assurance that the dial a flow is accurately functioning.
Now that you have completed this lesson, you should be able to define the differences between the manual pump and electronic pumps, calculate flow rates in gtts/min and mL/hr and finally, you should be able to compute a flow rate based on the amount of time for infusion.

Determine the flow rate.

Infuse an IV of D5NS (Dextrose 5% and Normal Saline or 0.9%) 1000mL q8hr.
What is the flow rate (mL/hr) the EID (Electronic Infusion Device) must be set at?

 To figure mL hr use the simple formula of volume time = flow rate

Volume = 1000mL and Time = 8 hr

 1000mL 8hr = 12.5 mL hr

The EID cannot infuse at that rate. You must round appropriately. The rule for rounding is that any remainder greater than or equal to 0.5 must be rounded up to the nearest whole number. Any value less than 0.5 is rounded down to the nearest whole number.

 The answer is to set the EID rate at 13 mL hr

Infuse an IV of LR (Lactated Ringers) 1000mL over 12 hours using an EID.
What is the flow rate?

 use the formula volume time = flow rate

Volume = 1000mL and Time = 12 hr

 1000mL 12hr = 83.3 mL hr

The EID cannot infuse at this rate. You must round appropriately. Since the value is less than 0.5 in the answer, the answer must be rounded down to the nearest whole number.

 The answer is to set the EID rate at 83 mL hr

An IV of 250 mL of D10 is to infuse at a rate of 50 ml/hr. How long will it take for this infusion to complete?

The simple formula of division can be altered slightly to answer this question:

 Volume x flow rate = time or volume flow rate = time

The Volume is 250mL and the rate of infulsion is 50mL/hr

Remember to set up your problem so that the proper units cancel. In this case, you need mL to cancel so 50 mL is placed in the denominator and 1 hour is placed in the numerator to accurately reflect the flow rate. Therefore, this IV infusion will take 5 hours to complete.

At midnight a client has 400 mL of IV solution infusing at a rate of 75mL/hr.

At what time do you anticipate the IV bag will be empty?

Use the same formula:

 Volume x flow rate = time or volume flow rate = time

The Volume is 400mL and the Rate of infusion is 75mL/hr

In this case, you need mL to cancel so 75 mL is placed in the denominator and 1 hour is placed in the numerator to accurately reflect the flow rate. It will take 5.3 hours to infuse. Fractional hours are converted to minutes by multiplying 60 minutes by the fraction obtained.

 Therefore, it will take 5 hours and 18 minutes to infuse. The original time was 2400 (midnight) so add 5 hours and 18 minutes. It will be 05:18 when this IV bag will be empty.

Remember to set up your problem so that the unwanted units cancel and the wanted units mg/hr are left.

Determine the drip rate (gtt/min)

The doctor orders an IV to infuse at 50mL/hr. Calculate the manual infusion rate in gtt/min for minidrip tubing (60gtt/mL). Determine the number of drops that should infuse in 15 seconds.

To solve for gtt/min, you can multiply the flow rate x drop factor x 1hr/60min

 Flow rate Drop Factor Conversion Wanted Quantity 50mL hr X 60gtt mL X 1hr 60min = 50 gtt min

Remember to set up your problem so that the proper units cancel.

A client is to receive 500mL of an antibiotic over 6 hours. The tubing to deliver the medication is calibrated at 10gtt/mL. Determine the manual flow rate in gtt/min. Calculate the number of drops that will infuse in 15 seconds.

To solve for gtt/min you will first need to solve for the flow rate in mL/hr.

 50mL 6hr =83.3 mL hr =83 mL hr

You must round appropriately. Since the value is less than 0.5 in the answer, the answer must be rounded down to the nearest whole number.

Now you can solve for gtt/min. gtt/min = flow rate x drop factor x 1hr/60min

 Flow rate Drop Factor Conversion Wanted Quantity 83mL hr X 10gtt mL X 1hr 60min = 13.8 gtt min =14 gtt min

Remember to set up your problem so that the proper units cancel. Also remember to round appropriately.

An IV infusing at 60 mL/hr is infusing through equipment calibrated at 20gtt/mL. Calculate the infusion rate in gtt/min. Then determine the number of drops that will infuse in 15 seconds.

To solve for gtt/min, you can multiply the flow rate x drop factor x 1hr/60min

 Flow rate Drop Factor Conversion Wanted Quantity 60mL hr X 20gtt mL X 1hr 60min = 20 gtt min

Remember to set up your problem so that the proper units cancel.

Now you can solve for how many drops will infuse in 15 seconds. To do this you will do the following
infusion rate (gtt/min) x 1 min/60sec (conversion) x 15sec/1

 Infusion rate Conversion Time needed Wanted Quantity 20 gtt min X 1min 60sec X 15sec 1 5 gtt every 15 seconds

Remember to set up your problem so that the proper units cancel. Approximately 5 drops should infuse every 15 seconds.