Needing math help please calculating flow rates? how do I do this?

morte, LPN, LVN · Oct 1, 2008

what are you looking for???

chordringer · Oct 1, 2008

dr's order: run 5% D?W at 100mL/Hr
Drop factor=10ggt/mL
please someone explain...:typing

Hey there, maybe this following explanation can help:

- I start with the order... which in this case is 100ml/hr (write this 100ml over 1 hr)

- We have to get this amount to be written as a gtt/min unit, so we need to convert the hours to minutes and the mL to gtt. This isn't too hard when you introduce unit factors that will convert the initial value over to the final value. We know that 1 hour is equivalent to 60 minutes. We also know that the drop factor is 10 gtt per 1 mL.

So we would set up the equation in a manner that allows the unneeded unit to be cancelled out:

100 ml 1 hour 10 gtt

------ x ------ x ------

1 hour 60 min 1 ml

Note that the hour units will cancel out... and the ml units will cancel out as well. The rest is simple multiplication:

1000 gtt 100 gtt

-------- = -------

60 ml 6 ml

By dividing 100 by 6, we come up with approximately 16.666 gtt/ml. However, you cannot express the answer in this form when using gtt, so we write it as a range: 16-17 gtt/ml.

Hope this helps!

Chord

P.S. Sorry about how the text doesn't line up too well with those fractions... I'm a newb and don't quite know how to make it look better.

IVRUS, BSN, RN · Oct 1, 2008

dr's order: run 5% D?W at 100mL/Hr
Drop factor=10ggt/mL
please someone explain...:typing

Tiffany,

One easy way to find gtts per minute is to use this formula;

Once you have your flow rate (In this case it is given to you=100mls/hr)

then it is simple division...

If your IV tubing is 10gtts/ml, divide flow rate by 6 to get gtts/min

If your IV tubing is 15gtts/ml, divide flow rate by 4

If your IV tubing is 20gtts/ml, divide flow rate by 3

So, first and foremost, get your flow rate.

Then this formula can easily be remebered by thinking of a clock...

How many 10 second increments are there in a minute? ...6

How many 15 second increments are there in a minute? ...4

How many 20 second increments are there in a min ute? ..3

:yeah:

hisblueskies · Oct 1, 2008

IVRUS -

Your way is the way I learned how to calculate flow rate. It is so simple doing it that way. I tried to teach my sister to do it this way when she was taking a pharm tech class and she just couldn't get it.

mrscoozy · Oct 3, 2008

well here's my 2 cents....

i just finished nursing school and i've learned it every was possible. i think the easiest is:

take amt of ml's times the drop factor and divide that by the number of minutes it is to be infused.....

simple simple:twocents:

redlabel · Oct 6, 2008

well here's my 2 cents....
i just finished nursing school and i've learned it every was possible. i think the easiest is:
take amt of ml's times the drop factor and divide that by the number of minutes it is to be infused.....
simple simple:twocents:

thats right! always multiply that amount of ml to the gtt and then divide in minutes; so if the given is in hour multiply it in 60 to make it min not confusing huhh. very simple.

thanks for everybody who share their knowledge..