Math problems

november17, ASN, RN · Jan 14, 2014

The drop factor is 10 gtt/min

this should read 10gtt/ml or whatever.

missmollie, ADN, BSN, RN · Jan 14, 2014

DosageHelp.com - Helping Nursing Students Learn Dosage Calculations - Volume/Time - IV Drop Rate Questions

Formula: (Volume/min) x gtts/ml

[1000ml/(10 hrs x 60 min)] x 10 gtts=

(1000ml/600) x 10 gtts=

1.6666666667 x 10 gtts=

16.666666667 drops/min: rounded: 17 gtts/min

I could be wrong here, but following the formula that's what I got. Go to that website, click on practice problems, pull down menu switch to "Volume/Time IV rates" and see if that helps. Best of luck!

hglover17 · Jan 14, 2014

this should read 10gtt/ml or whatever.

Thanks, I think the instructor messed up when typing the question and I should be trying to find gtt/ml. Thanks again..

Esme12, ASN, BSN, RN · Jan 14, 2014

Common drop factors are: 10 drops/ml (blood set), 15 drops / ml (regular set), 60 drops / ml (microdrop).

To measure the rate we must know:

(a) the number of drops

(b) time in minutes.

The formula for working out flow rates is:

[TABLE=class: cms_table_MsoNormalTable]

[TR]

[TD]

volume (ml) X drop factor (gtts / ml)

_____________________________

time (min)

[/TD]

[TD]

= gtts / min (flow rate)

[/TD]

[/TR]

[/TABLE]

Example:

1500 ml IV Saline is ordered over 12 hours.

Using a drop factor of 15 drops / ml, how many drops per minute need to be delivered?

[TABLE=class: cms_table_MsoNormalTable]

[TR]

[TD]

1500 (ml) X 15 (gtts / ml)

_______________________

12 x 60 (gives us total minutes)

[/TD]

[TD]

= 31 gtts / minute

[/TD]

[/TR]

[/TABLE]

iluvivt, BSN, RN · Jan 14, 2014

A quick way to do this especially if you are running out of time during test taking is to calculate the rate needed per hour and this case it is 100 ml per hour. Then depending on the drip factor divide by a certain number.So for example, in this case the drop factor is 10 so just divide the ml per hour by 6 since 10 x 6 is equal to 60. So 100 divided by 6 is equal to 16.66.

So drop factors: 10 divide by 6

12 divide by 5

15 divide by 4

This works in clinical practice as well and it is fast! Try it you will like it,

bluedove1 · Jan 15, 2014

Thanks I think the instructor messed up when typing the question and I should be trying to find gtt/ml. Thanks again..[/quote']
You should still be trying to find gtts/ min but November was just pointing out that your drop factor was written wrong which is what you will need to have correct in doing dimensional analysis or any canceling problem

nurseprnRN, BSN, RN · Jan 15, 2014

"Gtt factor" is always gtts/cc. Always.

I see a lot of people plug every number they're given into a DA formula and get the wrong answer because they put the numbers in the wring place or because the problem actually being asked doesn't require the tripartite DA formula to solve it. This one does, but clearly you have to know what they parts mean, or you'll get tripped up.

I think that for some people breaking down the problem into its component parts works out better, because they can see where they're coming from and where they're going more clearly.

For this example: 1000cc in ten hours. OK, that's doable in your head: 100cc/hour.

You want drops/minute, so you can think: How many cc/minute? That would be 100cc/60 minutes = 1.66cc, or 1.7 cc to give in a minute.

If there are 1.7 cc in a minute, and the IV set delivers 10 drops per cc, then that's ... 1.7 x 10 = 17 drops per minute.

If the set delivers 15 drops per cc, that would be 1.7 x 15 = 25.5, or 26 drops/minute.