How do I recalculate flow rates for infusions?

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1. An IV of 500mL was ordered to infuse in 3 hr using a 15gtt/mL set. With 1 1/2 remaining, you discover that only 150 mL is left in the bag. At what rate will you need to reset the flow?

2. An IV of 1000mL was ordered to infuse in 8 hr. With 3 hr of infusion time left, you discover that 600 mL have infused. The set delivers 20gtt/mL. Recalculate the drip rate, and indicate how many drops you will count in the 15 sec to set the new rate.

Simple math. Do the stuff in parenthesis first, left to right...

150mL/90 min = 1.67 mL/min. Then multiply by the gtt factor.

1.67 mL/min * 15gtts/mL = 25 gtts/min.

As to why we weren't helping that much is that we generally prefer to point the way to the solution and if you follow the pointing, you'll arrive at the solution yourself and understand the result much more concretely than if we spoon feed you the answer.

That method does not work for everyone. I like for someone to work the problem out so that I can see all of the steps and how it was solved. Maybe there was a step that I missed. This forum was made to assist students so I expect people to want to actually help
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That method does not work for everyone. I like for someone to work the problem out so that I can see all of the steps and how it was solved. Maybe there was a step that I missed. This forum was made to assist students so I expect people to want to actually help

This is how I learned how to do flow rates in my Medical Dosage Calculations class and how I used to do it when I was a pharmacy tech. Now that I am in the ADN program, I still do it the same way. So I wasn't aware I was missing steps. The way I posted it has all the steps, in my opinion.

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(400ml/3hr)(1hr/60min)(20gtts/ml)= 44.4gtts/ml or about 44gtts/ml

Over 15secs, you would count 11gtts

so anything over 15 seconds makes it 11/gtt?

I dont understand how you got 44 from that equation. can you break it down for me?

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Specializes in Emergency Department.

Oh, and I missed a small step: how many gtts in 15 seconds. Answer: approximately 7. (25/2)/2=6.5 gtts/15 seconds.

I calculate the rate per minute and then determine the gtt rate/min from that. When I need to answer a rate/hour, I just calculate that instead. It's just some basic math stuff.

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so anything over 15 seconds makes it 11/gtt?

I dont understand how you got 44 from that equation. can you break it down for me?

400/3= 133.33

1/60=0.0166

20/1=20

133.33x0.0166x20=44.26

It should be 44gtts/min. My previous answer said 44gtts/ml.

1min=60sec

60sec/15secs=4

44/4=11

11gtts/15sec

All you have to do is the math inside the parentheses and you will get your answer

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Remember this equation and then just plug in your numbers: ml/time x gtt

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Specializes in Critical Care, ED, Cath lab, CTPAC,Trauma.
That method does not work for everyone. I like for someone to work the problem out so that I can see all of the steps and how it was solved. Maybe there was a step that I missed. This forum was made to assist students so I expect people to want to actually help
HI! Welcome to AN! We are happy to help with homework.....but we won't do it for you. Everyone has been very helpful to you and given you plenty of information. I always ask for what you have done so far so I can best help you k now where you are going awry so I cab best help you stay in the right track.

Yes, this forum was made to help students...but it also states

This is NOT the forum to ask someone to do your homework for you. When asking for assistance with an assignment, please show what you have done first.
Med calculations, while challenging at first, are imperative to a safe practice of nursing...unlike other professions nursing requires you to remember that a majority of what you learn for you will be using it every day....there is very little "worthless" information.

The site that someone gave you earlier in the thread is an important one and a valuabvle one especially for students.

Formula: for gtt(drop)factor

[TABLE=class: formula]

[TR]

[TD][TABLE=class: fraction]

[TR]

[TD=class: numerator] Volume (mL)[/TD]

[/TR]

[TR]

[TD=class: denominator] Time (min)[/TD]

[/TR]

[/TABLE]

[/TD]

[TD] x Drop Factor (gtts/mL) = Y (Flow Rate in gtts/min)[/TD]

[/TR]

[/TABLE]

[TABLE]

[TR]

[TD][/TD]

[TD=align: right]

[/TD]

[/TR]

[TR]

[TD=colspan: 2][/TD]

[/TR]

[/TABLE]

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Specializes in Critical Care, ED, Cath lab, CTPAC,Trauma.
Wait I still don't see how you got 25 for this one..I'm getting 9
watch you conversions. Most problems have several steps....first..what is the question asking.
An IV of 500mL was ordered to infuse in 3 hr using a 15gtt/mL set. With 1 1/2 remaining, you discover that only 150 mL is left in the bag. At what rate will you need to reset the flow?
So the patient need to get 500cc's in3 hours....someone set the pump wrong and you need to correcct it.

You now have only 150cc's of IVF left and that need to infuse over 1 and 1/2 hour. HOw many minutes are in 1 and 1/2 hour.....(if there are 60 min per hour how many min are in 1 1/2 hour?) YThe are 90 min in 1 1/2hour.

so I have 150cc of IVF that needs to infuse over 90 min.Formula:

[TABLE=class: formula]

[TR]

[TD][TABLE=class: fraction]

[TR]

[TD=class: numerator] Volume (mL)[/TD]

[/TR]

[TR]

[TD=class: denominator] Time (min)[/TD]

[/TR]

[/TABLE]

[/TD]

[TD] x Drop Factor (gtts/mL) = Y (Flow Rate in gtts/min)[/TD]

[/TR]

[/TABLE]

150cc

90min X 15 =

so 150 divided by 90 equals...What?...multiply that times the drop(gtt) factor of 15 and you get the new pump setting to infuse that 150cc one 1 and 1/2 hour.

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So you have 400ml of the 1000ml left to infuse at a rate of 20gtt/ml

(400ml/3hr)(1hr/60min)(20gtts/ml)= 44.4gtts/ml or about 44gtts/ml

Over 15secs, you would count 11gtts

where does the 1hr/60 minute equation come from??? my book teaches me something different

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Specializes in being a Credible Source.
So you have 400ml of the 1000ml left to infuse at a rate of 20gtt/ml (400ml/3hr)(1hr/60min)(20gtts/ml)= 44.4gtts/ml or about 44gtts/ml Over 15secs, you would count 11gtts
where does the 1hr/60 minute equation come from??? my book teaches me something different
The factor 1 hr/60 min is simply to convert the drip rate into a per-minute form (as asked for) rather than the per-hour form.
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An I.V of 800mL was started at 9:am to infuse in 4 hr. At 10am, 150mL have infused. The set is calibrated at 15/gtt/mL. Recalculate the flow rate in gtt/min.

Okay so I set it up like this (650ml/4hr) (1hr/60)(15gtt/ml) and i still got the wrong answer. what am I doing wrong??

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An I.V of 800mL was started at 9:am to infuse in 4 hr. At 10am, 150mL have infused. The set is calibrated at 15/gtt/mL. Recalculate the flow rate in gtt/min.

Okay so I set it up like this (650ml/4hr) (1hr/60)(15gtt/ml) and i still got the wrong answer. what am I doing wrong??

You wouldn't be infusing it over 4hrs. It would be 3hrs because 1hr has already gone by.

(650ml/3hrs)(1hr/60min)(15gtts/ml)= ?

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