A walk-through of calculating pediatric ibuprofen doses using dimensional analysis. Lucy needs 130 mg after surgery, and the medication is 100 mg per 5 mL, so the dose works out to 6.5 mL. The presenter shows the six-step method for converting milligrams to milliliters.
Let's walk through a Does calc practice question your patient? Lucy just had her tonsils and adenoids removed and is scheduled for ibuprofen, 130mg every six hours. Q6H as needed, PRN for two days following surgery, she's being discharged, and her mom asks how many milliliters of Motrin she should give to Lucy for the next dose. At home, she shows you the bottle of ibuprofen, which reads 100 milligrams per 5 mils. How many MLS will you tell her to give her? All right, so anytime we do a dose calc question, we always want to make sure that we're following our six steps. So we start always, always with what we need at the end. So what are the units that we need to end up with? And here in the question, it's asking us how many mls to give to Lucy. So we're going to end up with milliliters at the end. Now, the second step is, what's the order? So what did the doctor actually. So we're gonna write this here on the left. Now, the order says that she's ordered 130 milligrams every six hours. So 130 milligrams. Now, step number three is what conversions do we need? What conversions are gonna work to help us get from milligrams here to milliliters over here? And so when we look back in the question, the question says, it gives us a conversion here. It says there's a. The bottle is concentrated at 100 milligrams per 5 ML. So we have milligrams, we have MLS, and that's the conversion factor we're going to use here. So I'm going to put this over one so we don't get confused. 130mg over one. And then our conversions here, conversions is 5ml over 100mg. Now, anytime you set up dimensional analysis, you have to make sure your units cross out. So milligrams is on the top here, milligrams is on the bottom here. So those two cross out. We want to be left with mls up top, milliliters, which is exactly what we want. We want milliliters to stay on the top. We don't want it to cross out because that's what we need to end up with. Now, step number four is to solve the problem. We're going to multiply across the top, multiply across the bottom, and divide. So 130 times 5 is 650, and then 1 times 100 is 100 and that gives us 650 divided by 100 is 6.5 ML. So we're going to give Lucy 6.5 ML.
