Dosage Calc, part 31: Medication Titration

  • 00:00 Intro
  • 1:14 Example 1
  • 4:11 Example 1A
  • 5:28 Example 1B
  • 5:52 Example 1B Dimensional Analysis
  • 6:30 Example 1B Ratio & Proportion
  • 7:11 Example 1B Formula method
  • 7:50 Example 1C
  • 8:34 Example 1C Dimensional Analysis
  • 9:27 Example 1C Ratio & Proportion
  • 10:37 Example 1C Formula method
  • 11:27 Example 1E

Full Transcript: Dosage Calc, part 31: Medication Titration

Hi. This is Cathy with Level Up RN. In this video, I will be explaining the concept of medication titration and provide examples of medications that are often titrated. I will then work through an example problem that involves medication titration. And I'll be working through this problem on my whiteboard using three different methods including dimensional analysis, ratio and proportion, and the formula method. 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 titrating medications in the critical care setting is very, very common. And what I mean by titration of medications is we are going to increase or decrease the dose of the medication that is provided to the patient based on certain patient parameters. So common medications that are titrated include antiarrhythmics such as diltiazem or amiodarone. Vasopressors are also titrated, such as epinephrine or dopamine. Heparin is titrated as well as insulin. And then analgesics such as fentanyl could be titrated as well. In terms of those patient parameters that dictate whether we increase or decrease the dose, some of those parameters can include the patient's heart rate, their blood pressure, their blood glucose level, their aPTT level, their pain level, as well as their sedation level, just to name a few examples.

The example on the board that I'm going to work through deals with an antiarrhythmic agent, diltiazem. So with this problem, we have an order for diltiazem 0.25 milligrams per kilogram IV bolus to be given over two minutes. We need to give diltiazem at 5 milligrams per hour after the bolus is given. And we need to titrate the infusion up or down by 5 milligrams per hour every 30 minutes to achieve heart rate and systolic blood pressure goals. And our goals are to bring the heart rate under 120 beats per minute and over 60 beats per minute. And we want our systolic blood pressure to be over 100 mmHg, and the maximum infusion rate of the diltiazem should be 15 milligrams per hour. All right. And what we have available to us is 5 milligrams per milliliter diltiazem for the IV push. And then we also have a 250 milligram in 300 ml of solution IV bag for the continuous infusion of diltiazem. And then we have our patient information here. So our patient's weight is 176 pounds. Their current heart rate is 220 beats per minute, and their blood pressure is currently 140/95. And I've written the first two questions on the board. There's actually five different questions we're going to work through with this example, but I want to make sure I left room for math because this is a pretty beefy problem.

All right. So let's go ahead and look at part A. So part A, or question A is asking us how many milligrams will be administered in the bolus dose? So per the order, we're going to be giving 0.25 milligrams per kilogram. And so now we need to know our patient's weight in kilograms in order to calculate that bolus dose. So our patient's weight is right here. It's 176 pounds. So if we divide this by 2.2 or multiply by the conversion factor, 1 kilogram equals 2.2 pounds, and if we do this math, we end up with 80 kilograms. So now I can take my patient's weight in kilograms and multiply it times the dose that was ordered for the bolus. So if we take this and multiply it by 80 kilograms, then we end up with a dose of 20 milligrams. So this is the amount of diltiazem that we're going to give for the bolus over two minutes. And that's the answer to A.

All right. Let's go now to part B. Part B asks us how many milliliters are going to be in that bolus dose. So I can use this dose in milligrams and calculate the milliliters using dimensional analysis, ratio and proportion, or the formula method. So we know our bolus dose is 20 milligrams. So let's first do this with dimensional analysis because it's the quickest way to do it. We'll take our dose for the bolus and multiply it by the available concentration for that bolus, which is 1 milliliter with 5 milligrams. And I purposely put my milliliters on top and my milligrams on bottom such that my milligrams will cross off and I'll be left with milliliters. So if you calculate this out, you end up with 4 milliliters. So that's how many milliliters are in the bolus dose. I totally could have solved this with ratio and proportion as well. So if I wanted to do that, I would put my known ratio on one side of the equation, so that is our available concentration for the bolus. And then on the other side, I would put an X for the unknown value because we're trying to figure out how many milliliters to administer and put our dose down here that we calculated in part A. And then I would do my cross multiplication here. So I have 5X equals 20. And if I solve for X, again, I end up with 4 milliliters. And then finally, I could use the formula method to do this same math. So the formula method is desired over half times the vehicle. So our desire is 20 milligrams. And what we have is 5 milligrams in 1 ml of solution. So if I do this math again, I end up with 4 milliliters. So that is part B of this problem.

All right. Let's work through the next three questions for this problem. So part C is, what is the initial infusion rate in milligrams per hour? So we can actually get that from the order. So if you recall, it said here to give diltiazem at 5 milligrams per hour after the bolus is given. So the answer to this question is 5 milligrams per hour. Now, in part D, we are being asked, what is the initial infusion rate in milliliters per hour? So in order to solve that, we can use dimensional analysis or ratio and proportion or the formula method, actually. Dimensional analysis is definitely going to be the most straightforward way to solve it. So we would take our initial infusion rate in milligrams per hour and then multiply this by the available concentration of diltiazem for the continuous infusion. So I would just put 300 milliliters over 250 milligrams. I'm purposely putting my milliliters on top and my milligrams on bottom so that my milligrams will cross off. And when I multiply this out, I will end up with milliliters per hour, which is what I am looking for. So if we multiply this out, we end up with 6 milliliters per hour. Okay. So that's how I would solve this with dimensional analysis.

All right. Let's solve this same part of the problem using ratio and proportion. So we know we want to give this medication at 5 milligrams per hour, but we need to figure out how many milliliters to give per hour for those 5 milligrams. So I'm going to set up my ratio. On one side of the equation, I'm going to have my known ratio, which is our available concentration, 250 milligrams in 300 ml. And then on this side, I'm going to put my 5 milligrams and an X for the ml because that's what I'm trying to figure out. And then I would cross-multiply here. So 250X and 300 times 5 equals 1,500. And then if I solve for X, I would end up with 6 milliliters. So I would give this medication at a rate of 6 milliliters per hour. And that is how you would get to the same answer using ratio and proportion. Again, with the formula method, that's another way we can solve this. Again, we're trying to go from 5 milligrams per hour to milliliters. So with the formula method, we have desired over half times vehicle, so we are desiring or we want 5 milligrams. What we have are 250 milligrams in 300 mls of solution. That is our vehicle. And if we do this math, again, we end up with 6 milliliters. So we need to give this at a rate of 6 milliliters per hour. Okay. So those are three different ways to solve part D of this problem.

Now let's work through Part E of this problem. So E says, after 30 minutes, the patient's heart rate is 160 beats per minute, and their blood pressure is 130/90. Will the infusion be titrated? If so, what is the new rate in milligrams per hour? Well, if you recall in our problem here, in our order, our heart rate goal was under 120 beats per minute, so we are not there yet. 160 is over 120, so we have not achieved our heart rate goal. And then our patient's blood pressure is 130/90. Their systolic blood pressure is over 100, so blood pressure's okay. Heart rate is not. Therefore, we are going to titrate this medication up by 5 milligrams per hour. So we would take it from the initial rate of 5 milligrams per hour up to 10 milligrams per hour. So we're going to titrate it up, and it's going to now be running at 10 milligrams per hour. And that is the answer to E.

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