Hi it's Tammy and today we're looking at IV therapy. Specifically, we're going to
be looking at how to calculate an infusion rate when we are given a volume
and a time and the second thing is looking at our drip rate when we do not
have a pump and we need to hang by gravity. Before we get started there's a
few things I just want to touch on. First is dimensional analysis.
That's a problem-solving tool I like to use and if you're not familiar with it
you can click on the link that's popping up and take that tutorial first and then
come back and join us. Second there are two free quizzes in the description box -
you know where to find them - download those and take advantage of that self
assessment piece and, third subscribe and make sure you leave me a comment to let
me know how these videos help you. So we're gonna start with drip factors and
I'm gonna see you at the board. Before we start I just want to review the drawing
on the right hand side of the page. We're looking at the difference between macro
and micro drips. In the macro lines the drops are larger which means it takes
fewer to make one ml. Here's our you're going to find your 10 drops, 15 drops or
20 drop per ml lines. In a micro drip you can see that the drops are smaller
and it takes more drops to make 1 ml. This is where we find the 60 drop per
ml line. We control the rate of the fluid by the roller clamp, moving it up
and down to get the rate just where we want it. Now with that we can start our
first question. We have an order for 250 mls of D5W over 2 hours.
The drip factor is 15 drops per ml and we want to know how many drops per
minute. So the first thing I want to know is what do I need to solve for? And
that's drops per minute. Next I'm gonna put in what do I know already. Well I
know that this line takes 15 drops to make 1 ml and I want to get rid of mls
and convert this to minutes and so I look and I see I have 250 mls in two
hours. And I still need to convert those hours to minutes so I'm going to put in
my conversion and now I have isolated my drops per minute and I can solve this
equation. So 15 drops times by 250 times by 1/2 times 60
minutes if I bring up my calculator to the calculation quickly it is 3750
drops divided by a 120 minutes. Further this out and you can see
that the answer is 31.25 five drops per minute however we always
round up or down to the nearest number. So this will be 31 drops per minute.
Okay here we have another order 250 mls over one hour and I have an IV set that
has 60 drops per ml and I'm looking for drops per minute. So as always, what
is the question asking me to find and I'm going to start with that drops per
minute. Then I need to identify the key information. So what do I know? I know
that I have a tube that it takes 60 drops to make one ml. I also know that I
have an order of 250 mls over one hour and that will allow me to cross off the
mls. Remember these are not fractions but these are relationships. And then I
have to do a conversion. I know that in one hour there are 60 minutes. This will
allow me to cross off the hours and then you can see now I have isolated my drops
in the numerator and my minutes in the denominator and I can go ahead and solve
this equation. So on the numerator I have 60 drops times by 250 times by 1 and in
the denominator I have 1 times 1 times 60 minutes. Pull up my calculator and you
can see that this is 15,000 drops divided by 60 minutes, further calculate
this out and the answer is 250 drops per minute. Now it could go back a step where
we had our 60 drops times by 250 divided by 60 minutes the 60s would cross off
leaving us with simply 250 drops per minute. That's another way to solve. Okay
one final example. Patients receiving 416 mls of blood over four hours and our
drip rate is 20 drips per ml. So what are we looking for now? I want to know how
many drips per minute. I know I have 20 drops per mls, so I put that into my
equation. I want to cancel out mls so again the relationship is 416 mls over
4 hour. I again want to get rid of hours and I'm going to put in my conversion of
1 hour is 60 minutes. Then I have isolated my drops of my minutes and I
can solve this equation. So I'm going to carry on with the
factoring out here 20 drops times 416 times by 1 divided by 1 times 4 times 60
Pull up the calculator and you can see 20 times 416 is 8320 drops and I'm going
to divide that by 240 minutes. And I will put my units back up here. Furthering this
calculation you can see that the final answer is 34.66
drops per minute, again we want to round to the nearest whole number so this
would be a thirty-five drops per minute.
Okay we're now more at the word problems for infusion based questions. In this
question I am looking for an hourly rate of an infusion; mls per hour. I can see
that over 24 hours I have a fluid balance of minus 640 and it's been
ordered as a replacement of one to one with normal saline over four hours. So
when I plunk in my 640 over four hours I can immediately solve this equation. 640
divided by four is equal to 160 mls per hour.
All right in this question we need to be careful and watch out for information
that we don't need. So I always start out with what do I need to know. In my last
sentence what does the infusion rate in mls per hour. So I'm looking for volume
over time. Now when I go read the question there's a lot of information in
here. I have solu-Cortef 50 milligrams diluted in a hundred ml bag of normal saline. My
patient has a 22-gauge Cathalon that will infuse over 15 minutes and the IV
drip factor is 10 drops per ml. So there's a lot of things to look at. What
I'm specifically curious about is the hundred mls over 15 minutes. So I'm
going to put that into my equation and I am looking for mls per hour though.
15 minutes needs a conversion into hours. So I know from my conversion table
that there are 60 minutes in one hour, so I'm going to add that to my equation. I
now have my units of mls per hour isolated and I can solve. So 100 mls
times 60 divided by 15 hours pull up the calculator and you'll see that this is
6000 mls divided by 15 hours and let's further finish this off and it
is 400 mls per hour. In another way to write this 100 mls times by 60 over 15.
15 goes into 60 four times so I can get rid of the 15 and it's simply 100 times
4 which equals 400 mls per hour. And we've made it to our last question of
this practice. Ancef one gram is to be infused one hour prior to the OR. It is diluted
in 100 mls of normal saline and to go over 30 minutes.
What is the infusion rate? Again I'm looking for volume over time; mls per
hour. So I go back to my question - what do I have in there that would satisfy this
equation? I have a hundred mls over 30 minutes. Just like our last question, I
need to convert minutes to hours so I know that there are 60 minutes in every
hour. I'm going to add this into my conversion, and
cross off my minutes and I'll be able to solve. So this leaves us 100 mls times
60 divided by 30 times 1 hour - bringing up the calculator you can see this is
6,000 mls divided by 30 hours and completing this calculation this rounds
out to 200 mls per hour. Fantastic. There you have it we've
completed our infusion calculations and our drip rate calculations. Don't forget
those free quizzes to help you with your self-assessment. Comment below let me
know how this went for you and subscribe. There'll be new videos coming out
regularly until next time, take care.