d/h x v is used with dosage calculations in the medical office. medical assistants use this calculation to prepare injections for their patients.
The best way to explain this formula to students is to tell them what d (desired dose), h (dose you have, or dose on hand), and v (volume), and provide a couple examples. (An example: Morphine Sulfate 4mg IV ordered, available dosage is 10mg in 2 ml. How many ml will the nurse administer? 4/10 x 2= 0.8ml) Go over other examples, and they should be able to do the calculations on their own from there. I am not terribly fond of this formula, since it is easy to overlook conversions that need to be done, and can lead to big mistakes. I prefer to start by recognizing the units I need to end up with to get the proper dosage, then make an estimate of what I think the dose should be, then carry out the calculations. If my estimated dose is very different than my calculated dose, I can rework the problem. I know this sounds more complicated, but it actually works faster for me, and I know for sure I have figured it out right. I have heard so many stories about medication errors that resulted in patients receiving as much as 100x the ordered dose, due to a math error. I always wonder if the person administering the medication had taken the time to make a rough estimate of the dosage before doing the calculation, they would realize that it is not reasonable to have to use 4 vials of a medication for a single dose, or that a heparin drip probably shouldn’t be running at 250 ml/hour.
Need to explain the variable, what it means and then have them plug in. Honestly not enough information.
I want to praise Sarah for her common sense. She said, “Think! Make an estimate. Do the math. If the estimate and the math don’t agree… Go to “Step 1”.
When I taught 5th and 6th graders I would scribble “DMAMS” on the board. The kids thought I was swearing until “we” figured out it meant “Does my answer make sense?”