Hi, this is Cathy with Level Up RN. In this video, I will be working through a couple of pediatric dosage calculation problems that involve the dilution of formula and the strength of feeds. You can find all the information that I'll be covering in this video in our Level Up RN dosage calculation workbook. If you are in nursing school, then you know how important it is to master dosage calculations, and our workbook will help you do just that. In a nutshell, our workbook contains all different types of dosage calculation problems that you are likely to encounter in nursing school. And we demonstrate how to solve each problem using multiple methods so you can pick the way that makes the most sense to you.
So premature infants and low birth weight infants will often require formula if breast milk is not available. And there are some studies to suggest that full-strength formula can be associated with feeding intolerance and certain complications, so the provider may order the formula to be diluted prior to administration. So in this first example, we are being asked how much water is in a 500 ml feeding that is three-quarters strength? And we need to round our answer to the nearest whole number. So when we say three-quarters strength, that means in this 500 ml feeding, three-quarters of it is comprised of formula, and the other quarter is water. That's what we mean when we say three-quarters strength. So in order to calculate the amount of water that is in this 500 ml feeding, we just need to take 500 mls and multiply times a quarter or 0.25. And if we do this math, we end up with 125 mls. That is how much water is in this 500 ml feeding that is three-quarters strength. And this is rounded to the nearest whole number already, so we are good to go as far as rounding.
Let's now work through our second example problem. In this problem, we have an order to administer formula at three-quarters strength at 30 milliliters per hour to our patient with a G-tube. And formula is supplied in a 240 ml container, and we need to round all our answers to the nearest whole number. So before I read out the questions here, I want to give you guys a little spoiler alert, which is this 30 mls per hour is irrelevant for the questions being asked. And you'll see that happen a lot with dosage calculation problems. They'll throw a bunch of numbers at you, and some or half of those numbers won't even be relevant for the questions being asked. So definitely don't freak out at all the numbers being thrown your way. Just consider what you need to consider to answer the problems at hand. Okay. So our two questions being asked, how much water would we add to the can of formula to make it three-quarters strength? And what is the total volume that will need to be administered to our patient? So there are really two main ways that we can solve this problem. So I'm going to go through option one first, and then I'll go through option two, and you can see which way makes the most sense to you.
All right. So with option one, we know that our 240 ml of formula is going to be three-quarters of the final solution, right? The final volume because we need to add water to it. So we can actually set up an equation here. We can say 0.75, which is three-quarters of the final volume of the solution, which we don't know what that volume is, so it's X equals 240 ml. So three-quarters of the final solution will be that 240 mls of formula. And we just need to solve for X now, so X equals 240 ml divided by 0.75. If we do this math, we end up with 320 ml. So 320 ml is the final volume after we add the water, right? So to figure out how much water is in that 320 ml, I would take that 320 ml, subtract out my formula volume, which is 240 ml, and I end up with 80 mls of water, okay? So we actually ended up solving part B of this problem first, which is the total volume, and we did that with this algebraic equation. And then to figure out how much water, we kind of answered that part of the question second. So we took the total volume, subtracted out the formula volume, and that gave us the amount of water.
All right. Let's work through the same problem using option number two. All right. Option number two. So with option number two, if we look at our order and they're telling us to administer this at three-quarters strength, that means that we have three parts which are going to be formula and one part that's going to be water. So part one is formula, part two is formula, part three is formula, and this last part is water. So this means three parts formula, one part water. So for these three formula parts, we're going to get those from the 240 ml container of formula. So if we take 240 mls divided by 3, we get 80 mls. So each of these parts is 80 mls, right? 80, 80, 80. You add that up, that's 240 ml. But then we need to add that other part of water, right? So that's another 80 ml down there. So if you look at our questions, how much water would you add to make it three-quarters strength, you're going to add 80 mls. And then what is the total volume that will be administered? We just have to add up these volumes, right? So we add up the 240 milliliters of formula plus that 80 mls of water, and we get 320 mls total volume. So that would be the answer to part B. So that's how you can think about this problem using option two. And you obviously should use whatever option makes the most sense to you.
