Learn the six-step dimensional-analysis method for nursing dose calculations. Patient Alex needs 150 mg of metoprolol twice daily, and you have 50 mg tablets. The method shows how to set up fractions so units cancel, then divide to get the answer: 3 tablets.
Let's walk through a doscalc practice question. This one says, your patient Alex is ordered to get 150 milligrams of metoprolol twice a day. His breakfast just arrived and he's asking for his medication. The med cart has 50 milligram tablets. How many tablets will you give to Alex? So anytime we're doing a dose calc problem, we always want to make sure that we are following our six step process. This is going to make sure that you get this question right every time and every dose calc question, right. So our first step here is, is what do we need at the end? We always want to make sure that we're solving the correct units. So here in the question, it's asking how many tablets we're going to give to Alex. So we write here on the right hand side, we're going to write tablets because that is what we need to end up with at the end. We want to make sure we're solving for the correct unit. Now the second step is, what is the order? What did the doctor actually order? The prescriber order. So here Alex is ordered to get 150 milligrams of metoprolol twice a day. So we're talking about how many tablets we're going to give to him this time. So what we have here is the order over here on the left side and that's 150 milligrams. We're going to put that over one so we don't get confused. And then step number three is what conversions do we need to, to work with here? What conversions are going to work to get us from milligrams over here in the order to tablets over here, which is what we need to end up with now. Anytime with this. We want to look at the question first when we look for conversions, look at what the question says. So it gives us a conversion here. It says The MedCart has 50 milligram tablets. So in every single tablet there's 50 milligrams milligrams in it. So we're going to say one tablet is equal to 50 milligrams. Now anytime you set up dimensional analysis like this for your dose calc exams, you want to make sure that the units you don't want at the end, you want those to cross off. So if you don't want them at the end, they need to cross out. One has to be at the top, one has to be at the bottom and they have to cross out. Now this is perfect because we have tablets here at the top and we need tablets at the end. Tablets is not crossing out. That's perfect. That's exactly what we want, because we want to end up with tablets at the end. So 150 times 1 equals 150. 50 times 1 equals 50 and 150 divided by 50 equals 3. So we're going to give three tablets.
