RN School: IV Regulator Dosage Calculation

Banana nut, BSN, RN, EMT-B · Oct 16, 2016

OK. I'm a student but I will give it me best explanation. So 130ml/90 minutes. So 90 minutes =1.5hr.

We can break up 90 minutes into 30 30 30.

If we divide 130/3= 43. So that means the pump is going to run at 43ml/30 minutes. So let's just double that and make it 86ml/60 minutes and let it run for 90 minutes.

Someone please stop me if I'm wrong.

chare · Oct 16, 2016

OK. I'm a student but I will give it me best explanation. So 130ml/90 minutes. So 90 minutes =1.5hr.
We can break up 90 minutes into 30 30 30.
If we divide 130/3= 43. So that means the pump is going to run at 43ml/30 minutes. So let's just double that and make it 86ml/60 minutes and let it run for 90 minutes.
Someone please stop me if I'm wrong.

Several of us could have worked the problem, and provided the OP an answer, however, there's a reason that we didn't, as he or she still wouldn't know how to work the problem.

Rather, if we ask the poster to show what he or she has done so far, we can see exactly where they are having difficulty. Knowing where the problem arises best allows us to help.

brains090 · Oct 16, 2016

Esme12 you are wonderful

! Volume(mL)/ time(hr) = Y (flow rate in ml/hr). 125ml of D5W +5ml septra/ 1.5hr = 86.66, rounded = 87 ml/hr.

Banana nut, BSN, RN, EMT-B · Oct 16, 2016

I am still stuck on the problem. Can someone explain this one to me? I have 8 more problems like this that I have to do.

The explanation provided was not making sense to the OP. Sometimes it takes someone giving a rational for a concept to sink in. OP has 8 more to do and I'm sure will have plenty after that.

Double-Helix, BSN, RN · Oct 16, 2016

OK. I'm a student but I will give it me best explanation. So 130ml/90 minutes. So 90 minutes =1.5hr.
We can break up 90 minutes into 30 30 30.
If we divide 130/3= 43. So that means the pump is going to run at 43ml/30 minutes. So let's just double that and make it 86ml/60 minutes and let it run for 90 minutes.
Someone please stop me if I'm wrong.

In my opinion, this is way over-complicating the problem. You have a total volume. Divide it by the number of hours you want to infuse it over and call it a day.

Banana nut, BSN, RN, EMT-B · Oct 17, 2016

In my opinion, this is way over-complicating the problem. You have a total volume. Divide it by the number of hours you want to infuse it over and call it a day.

I totally agree. Sometimes when you have a bunch of numbers but you don't know why or where exactly to plug all the numbers into an equation things can get confusing. Sometimes knowing how to break something down can help some people work through a problem or understand it better. This is how I learn. It helped me with dosage calc, rubicks cubes and all kinds of other fun things.

Yes plugging numbers into an equation is way easier but knowing what to put where can get students lost sometimes. I'm just thinking "outside the box"

Double-Helix, BSN, RN · Oct 17, 2016

I agree with providing rationale and showing how to break down an equation. The problem is, the method you used to solve OP's homework question is only applicable to this specific question. The steps of: "Break 90 minutes into 30 minute increments, Divide total volume by 3, Multiply that answer by 2." Only work when applied to a question that asks you to infuse over 90 minutes. What if the OP's next question asks him or her to infuse over 45 minutes? OP will not know how to solve that problem because the method of breaking down the volume into incriments of 30 doesn't work.

Conversely, using the formula in the link Esme12 provided:

Volume in mL/Time in hours=mL/hr

can be applied to any question regardless of the specific volumes or times provided. Does that make sense?

AliNajaCat · Oct 17, 2016

I like to use jelly beans.

You have to eat 130 jelly beans in an hour and a half. OK, they're really small ones or you'll get sick, but work with me here.

Lay out those jelly beans on the table and visualize dividing them. Fool around with it. Pretty soon you'll see that if you do divide them in three sections, one for each half an hour, you'll know how many you have to eat in half an hour, and, by extension, how many you'll consume in an hour.

Halloween is coming, so you'll have lots of candy corn to play with. The process is the same.

Jellybeen · Nov 17, 2017

I'm a year late but virtually no one directly answered the OP's question efficiently. I get helping someone think for themselves but we all have to when we are tested. Here is a place to fully explain it all.

Im surprised many folks completely left out the fact that in the problem, every order is half the available amount. Therefore, 10 mL (the available amount) should be cut in half and added to the instructed amount (125 mL). It would then become 130 mL to work with.

How I found my answer: 130 mL/90 min multiplied by 60 min/1 hour (for conversion purposes). This equals 86.666666... or 86.7 mL/hr. The pump is always rounded to the nearest tenth. The answer is actually not available in the question. I believe this was an error. My professor went over this exact problem today.

The purpose of my posting this is so that other nursing students can get a thorough answer. It's already obvious that you're trying work it out. Now try it on your own and see if you get the same answer. Good luck to you all!

KrCmommy522, BSN, RN · Nov 20, 2017

OK. I'm a student but I will give it me best explanation. So 130ml/90 minutes. So 90 minutes =1.5hr.
We can break up 90 minutes into 30 30 30.
If we divide 130/3= 43. So that means the pump is going to run at 43ml/30 minutes. So let's just double that and make it 86ml/60 minutes and let it run for 90 minutes.
Someone please stop me if I'm wrong.

This seems way more complicated than it has to be:

Order: Septra (trimethoprim 80mg and sulfamethoxazole 400mg) IV, q12.

Available: Septra (trimethoprim 160mg and sulfamethoxazole 800mg/10ml).

Set and solution: Volumetric pump regulator and125 ml of D5W

Instruction: Dilute Septra 80/400mg in 125ml of D5W and infuse in 90 minutes

Ok, for my drug calculation, I did a conversion problem. 800mg/10ml = 400mg/ x ml. I got 800x = 4000, and divided both by 800. That gave me 5ml. So, for my order I have sulfamethoxazole 400mg/ 5ml.
I need to find how many ml/hr the patient will receive via volumetric pump regulator. I know I am solving for ml/hr, and after that I am lost.

Okay, so...

You did your calculation and know that for your order you have 5 mL.

Your instructions tells you to dilute in 125 mL.

So: 5 mL (of ordered med) + 125 mL (of dilutent) = 130 mL total

You have to run the 130 mL over 90 min.

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You cancel out the minute units (90 min on bottom, 60 min on top) and you are left with the units you need: mL/hr.

Whens solving dosage calculation problems, I ALWAYS use dimensional analysis. It works for every dosage calculation problem I've had. Being able to follow along the path, crossing out units you don't need to get to the units you want, in my opinion, makes it so much easier! You don't have to worry about multiplying the wrong things (like the means and extremes with the ratio and proportion method). For me it just made it so much easier to be able to follow it along the path!

Some Good Sources for Dimensional Analysis:

I used this book: https://web.opendrive.com/api/v1/dow...O6emK?inline=1

Goes Through Dimensional Analysis Process Working Through Different Examples:

Dosage calculations the easy way! - Straight A Nursing

Sources that Show Different Methods of Calculations (e.g., basic formula, ratio proportion, fractional method, dimensional analysis):

nursesaregreat.com - Homepage

Page not found | Germanna Community College

Sources That Show Simple to Harder Dosage Calculation Problems:

The nurse's quick guide to I.V. drug calculations : Nursing made Incredibly Easy

DosageHelp.com - Helping Nursing Students Learn Dosage Calculations

These links are really worth checking out! Hope they help!

KrCmommy522, BSN, RN · Nov 21, 2017

I totally agree. Sometimes when you have a bunch of numbers but you don't know why or where exactly to plug all the numbers into an equation things can get confusing. Sometimes knowing how to break something down can help some people work through a problem or understand it better. This is how I learn. It helped me with dosage calc, rubicks cubes and all kinds of other fun things.
Yes plugging numbers into an equation is way easier but knowing what to put where can get students lost sometimes. I'm just thinking "outside the box"

I completely agree. That's why I've always liked dimensional analysis. I like that you start with what is ordered, and from there, follow along the path, canceling out unwanted units, until you get to the units you want. It just made it easier for me. It helped me know where to put the numbers.

Example: We know we have 130 mL and we need to run it over 90 minutes. We also know we want mL/hr. Finally, I know I can only cancel out units diagonally (i.e., units in numerator of one fraction can cancel out units in denominator of another fraction)

So, I start with 130 mL/90 min and I want to end with mL/hr

130 mL/90 min x ??

(what will cancel out the min in the denominator? A conversion factor of min/hr, it will give me the hr I need and will cancel out the min in the denominator of what I have, which will leave me with mL/hr. I know that I can only cancel diagonally, I want to cancel out the min in the demoninator of the first fraction, so min has to go in the numerator of my conversion factor = 60 min/1 hr)

130 mL/90 min x 60 min/1 hr =

Now, I cancel diagonally (cancel min in denominator of first fraction and min in numerator of second fraction). So, now I am left with mL in numerator of first fraction and hr in denominator of second fraction - so I have what I need: mL/hr. Now, I just multiply across the top (the numerators), and multiply across the bottom (the denominators) and then divide

130 x 60/90 = 86.66 = 86.7 mL/hr

It helps because I am working with a formula, but I always know to start with what is ordered, and then work my way across plugging in what I need and canceling out what I don't in order to get to the units I need.