# How do I recalculate flow rates for infusions? - page 2

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... Read More

1. Quote from EmilyEmily
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.
2. (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?
3. 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.
4. Quote from EmilyEmily

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
5. Remember this equation and then just plug in your numbers: ml/time x gtt
6. Quote from EmilyEmily
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
 Volume (mL) Time (min)

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

7. Quote from EmilyEmily
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:
 Volume (mL) Time (min)

x Drop Factor (gtts/mL) = Y (Flow Rate in gtts/min)
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.
Last edit by Esme12 on Jan 22, '13
8. Quote from Mina E.

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

Over 15secs, you would count 11gtts
where does the 1hr/60 minute equation come from??? my book teaches me something different
9. Quote from EmilyEmily
Quote from Mina E.
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.
10. 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??
11. Quote from EmilyEmily
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)= ?
12. Quote from Mina E.
You wouldn't be infusing it over 4hrs. It would be 3hrs because 1hr has already gone by.

(650ml/3hrs)(1hr/60min)(15gtts/ml)= ?
Thank you. I have a question about another problem I did

1. An IV of 500 mL that was to infuse in 2 hr is discovered to have only 150mL left after 30 minutes. Recalculate the flow rate. Set calibration is 15 gtt/mL

so I did 150/90min x 15gtt/mL which gave me 25. But why didn't the equation 1hr/60minutes apply to this one?? when I put that in there the answer came out wrong
13. Quote from EmilyEmily
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??
It's not four hours, since one hour has already passed.

Think about it in relative terms, too. You have 800 cc to give in 4 hours originally. That means you should be giving 200cc/hour, right? But when one hour has passed, only 150 cc was gone. So what does that mean/ Right, it was running too slowly. Someone miscalculated the rate. Yo will take the amount of fluid left, and figure out how to give that amount in the three hours remaining to you.

Slow down, read the question in parts, and don't go on to the next one until you completely understand what you have already. That means, can you explain it to someone else with confidence. No? You don't know it yet. Try some more.