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.

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

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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??

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.

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Specializes in Critical Care, ED, Cath lab, CTPAC,Trauma.
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. (what needs to infuse over the remaining 1 and 1/2hrs....OR (2hrx60min)-30min=90min.......becasue there is 60 min per hour...)

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

It doesn't work because you jare umping around.

In the above problem....look at what it is asking......Your IV bag ran in too fast You have to now change the gtt rate to infuse 150ml over the remaining 1 and 1/2 hours. (or 90min)

So.....your equation, using the 1hr/60min(to convert hrs to min), is..

(150ml/1.5hrs)x(1hr/60min)x(15gtts/min)=25gtts/min

OR.....your equation, with the mins already converted is...

(150ml/90min)x(15gtts/min)=25gtts/min

WATCH YOUR CONVERSION FACTORS!!!!

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

So....you have (150ml/1.5hr)x(1hr/60min)x(15gtts/min)=25gtts/min

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 which leaves 400ml left (1000ml-600ml=400ml) to be infused over 3 hrs. 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. (gtt rate 15gtt/min)

So what do you need to do here??

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Thank you. I have a question about another problem I did1. 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/mLso 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
When you set up this type of problem, you can use either hours or minutes as the infusion time. If you use hours you must include the 1 hour/60 minute conversion to obtain drops/minute.
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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

{{One hour will always be sixty minutes. If your problem asks you to solve for hours and it gives you minutes, convert minutes to hours. If it gives you hours and asks you to solve for minutes, convert hours to minutes.

Your question asked you to solve for a rate in one minute.}}

Let's see if we can think of another way to understand this problem. Hmmm. OK. The Girl Scout next door is selling those damn delicious Thin Mints. You want your box of thirty to last you one month (30 days). Your plan is to eat one cookie per day. Alas, on the 11th of the month you discover that there are only ten left. (You must have eaten extra ones in your sleep.) How often can you have a cookie to make them last the rest of the month?

You have ten cookies and twenty days. Therefore you can have one half cookie per day to make them last (good luck with that). Or one cookie every other day. Either way, it's fewer per day than you ate them before.

Sometimes it helps people to draw pictures of glasses of fluid, cookies, and hours (1,2,3,4,5...) Experiment.

You took algebra as a prerequisite. This is why. This is only addition, subtraction, multiplication, division (arithmetic) and basic algebra (solve for x).

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Thank you so much. I get it now!! I really appreciate you all being patient with me

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Specializes in Critical Care, ED, Cath lab, CTPAC,Trauma.
Thank you so much. I get it now!! I really appreciate you all being patient with me
I'm glad.....((HUGS)) you're welcome...:)
0 Votes
Specializes in Critical Care, ED, Cath lab, CTPAC,Trauma.

Know your conversion tables......

The Short List 1 cup © = 8 ounces (oz)

1 dram (dr) = 60 grains (gr)

1 dram (fl dr) = 60 minims

1 gallon (gal) = 4 quarts (qt)

1 glass = 8 ounces (oz)

1 grain (gr) = 64.8 milligrams (mg)

1 gram (g) = 15.43 grains (gr)

1 inch (in) = 2.54 centimeters (cm)

1 kilogram (kg) = 2.2 pounds (lb)

1 liter (L) = 1.057 quarts (qt)

1 milliliter (mL) = 16.23 minims

1 minim = 1 drop (gt)

1 ounce (oz) = 2 tablespoons (tbsp)

1 ounce (oz) = 8 drams (dr)

1 ounce (fl oz) = 29.57 milliliters (mL)

1 pint (pt) = 16 ounces (oz)

1 pound (lb) = 16 ounces (oz)

1 quart (qt) = 0.946 liters (L)

1 quart (qt) = 2 pints (pt)

1 tablespoon (tbsp) = 3 teaspoons (tsp)

1 teacup = 6 ounces (oz)

1 teaspoon (tsp) = 4.93 mL

The Long list

1 central = 45,359 grams (g)

1 centimeter (cm) = 10 millimeters (mm)

1 cubic centimeter (cc) = 1 milliliter (mL)

1 cup © = 8 ounces (oz)

1 drachm = 3.55 milliliter (mL)

1 dram (dr) = 60 grains (gr)

1 dram (fl dr) = 60 minims

1 gallon (gal) = 4 quarts (qt)

1 gill = 4 ounces (oz)

1 glass = 8 ounces (oz)

1 grain (gr) = 64.8 milligrams (mg)

1 gram (g) = 1,000 milligrams (mg)

1 gram (g) = 1,000,000 micrograms (mcg)

1 gram (g) = 15.43 grains (gr)

1 hand = 4 inches (in)

1 inch (in) = 2.54 centimeters (cm)

1 kilogram (kg) = 1,000 grams (g)

1 kilogram (kg) = 2.2 pounds (lb)

1 liter (L) = 1000 milliliters (mL)

1 liter (L) = 1.057 quarts (qt)

1 meter (m) = 1,000 millimeters (mm)

1 meter (m) = 100 centimeters (cm)

1 milligram (mg) = 1,000 micrograms (mcg)

1 milliliter (mL) = 1 cubic centimeter (cc)

1 milliliter (mL) = 15 drops (gt)

1 milliliter (mL) = 16.23 minims

1 minim = 1 drop (gt)

1 ounce (fl oz) = 2 tablespoons (tbsp)

1 ounce (oz) = 20 pennyweights (dwt)

1 ounce (oz) = 24 scruples

1 ounce (oz) = 31.1 grams (g)

1 ounce (oz) = 480 grains (gr)

1 ounce (oz) = 8 drams (dr)

1 ounce, fluid (fl oz) = 29.57 milliliters (mL)

1 palm = 3 inches (in)

1 pennyweight (dwt) = 24 grains (gr)

1 pint (pt) = 16 ounces (oz)

1 pint (pt) = 4 gills

1 pound (lb) = 16 ounces (oz)

1 pound (lb) = 350 scruples

1 quart (qt) = 0.946 liters (L)

1 quart (qt) = 2 pints (pt)

1 scruple = 20 grains (gr)

1 stone = 0.14 cents

1 tablespoon (tbsp) = 3 teaspoons (tsp)

1 teacup = 6 ounces (oz)

1 teaspoon (tsp) = 60 drops (gtt)

1 teaspoon (tsp) = 4.93 mL

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if we are to consider these questions are coming from a nurse on duty, how come you always come up with incorrect drop rates for your patients IV, you might end up doing more damage with IV overload on your patients, next time do the computations properly to avoid costly mistakes while on duty.....

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Specializes in Pedi.
if we are to consider these questions are coming from a nurse on duty, how come you always come up with incorrect drop rates for your patients IV, you might end up doing more damage with IV overload on your patients, next time do the computations properly to avoid costly mistakes while on duty.....

I think these questions are coming from a student doing homework... as this is the Nursing Student Assistance forum... and when was the last time you actually had to calculate a drop factor/drop rate on the job? In the real world, we'd be using IV pumps.

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Specializes in being a Credible Source.
In the real world, we'd be using IV pumps.
Not always...

I've been in the back of an ambulance sans pumps...

and in a rural ER...

and even emergently in the big city ER when we were temporarily out... or taking the patient to MRI

And not all pumps are "smart pumps;" some are just fancy dial-a-flows.

But obviously this is just a student who's in the right place...

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