IV Flow Rate Calculation (Nursing)

by Rhonda Lawes

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      Slides 10-02 IV gtt Drip Calculations.pdf
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    00:01 Now, let's talk about the fun stuff.

    00:03 Here is where the math comes in.

    00:05 The size of the IV drop is regulated by the IV tubing set being used.

    00:10 Okay, that means that in that drip chamber, when you see those drops come down, the volume or how much fluid is in that drop, the size of that drop is regulated by the tubing set that you're using.

    00:25 Now, you don't have to memorize this.

    00:27 But most hospitals have more than one size of infusion tubing.

    00:31 You'll just have to see when you get to the hospital and you're working in that setting.

    00:35 The cool part is you don't have to memorize it.

    00:38 The drip rate, now see that word, gtt, that's drip.

    00:43 That's how we abbreviate that.

    00:45 So when we say a drip rate, we also see gtt.

    00:49 The drips per mL is printed on each IV tubing package.

    00:53 Let's take a look.

    00:54 You have macrodrip tubing and microdrip tubing.

    00:59 Now, we use macrodrip tubing with adults.

    01:02 Now, look at that box right there with a number 10 in it.

    01:07 It says 10.

    01:08 That means it takes 10 drops in this particular tubing to make 1 milliliter.

    01:16 So, that's the drop factor of the tubing, 10 drops to make 1 milliliter.

    01:22 That means when I'm counting how much volume the patient is getting and I'm setting the rate manually, I'd look at the drops.

    01:29 I would have to count, one, two, three, four, five, six, seven, eight, nine, ten.

    01:40 That would equal 1 milliliter.

    01:43 Now, you notice when I did that counting, may have been annoying for you but sometimes it was slow and sometimes it was fast.

    01:50 That's what happens when you adjust the roller clamp.

    01:53 The tighter the roller clamp, the more pressure it's putting on the tubing, the slower the drops will go.

    02:01 You back off on that roller clamp and you have less pressure on the tubing, the faster the drops will go.

    02:07 So, that's what you want to know, that you control the drop rate by how tight that roller clamp is or how loose that roller clamp is.

    02:16 If the roller clamp is backed all the way off, it's going to flow really fast.

    02:21 You probably won't be able to count the drops because it's just going to be a solid stream.

    02:24 So, we have macrodrip tubing and microdrip tubing.

    02:30 Now, macrodrip sets have 10 drops per mL, 15 drops per mL, or 20 drops per mL.

    02:37 Remember, gtt means drops.

    02:40 So, this example we have in the big box, so you see 10.

    02:44 That would be 10 drops per mL, but other sets can be 15 or 20.

    02:49 You just have to look at the package that the tubing comes in to.

    02:53 This is what we predominantly use for adults.

    02:55 Now, we have microdrip tubing. It's 60 drops per mL.

    03:01 Wow, I would hate to count this. But it's 60 drops per mL.

    03:05 You'll see this if it's really crucial medication or with our pediatric patients because they are so sensitive to volume.

    03:13 Now, the practice questions we give you are not going to be 60 drops per mL.

    03:17 Thank goodness! We're going to stick with the macrodrip.

    03:20 But we wanted you to know that that type of tubing is out there and used with very special populations.

    03:26 Now, let's look at some IV fluid order examples.

    03:29 Most often, an IV order will be written with an hourly rate for the IV fluid.

    03:34 I'm going to show you three examples of what you might see in a patient's chart.

    03:38 0.9% normal saline at 125 mL per hour, that means I'm going to hang a bag of normal saline, 0.9%.

    03:49 I want it to run at 125 mL in hour.

    03:55 So if I want that patient to receive 125 milliliters of normal saline every hour, I'll hang it and that will just continue to flow.

    04:06 It doesn't give me any type of time limit, how much to put in.

    04:10 It just says start an IV going at 125 an hour.

    04:14 Now, as a responsible nurse, I'm going to keep communicating with the healthcare provider and see how long the patient needs to continue this level of therapy.

    04:22 But let's look at a different order.

    04:24 Ah, what's different about this one is it tells us just for eight hours.

    04:29 Now, if you multiply 125 times 8, that should come up to 1000 milliliters.

    04:38 Well, this indicates the healthcare provider wants this patient to just get 125 milliliters per hour for 8 hours.

    04:46 Roughly, they're going to get a thousand milliliters of fluid in.

    04:50 After the eighth hour, the IV should be discontinued if the healthcare provider has not ordered additional fluids.

    04:58 Now, look at the third order.

    05:00 This one says 0.9% normal saline at 125 milliliters per hour for a total of 2000 milliliters or 2 liters.

    05:11 Okay, so these are just three different formats of how you might see an IV order.

    05:16 The first one, I'm going to hang the IV and it's going to continue at 125 milliliters an hour.

    05:21 I'm going to keep a really close eye on my patient because any time I hang IV fluid, we're risking fluid volume overload.

    05:28 I'm going to keep communicating with the healthcare provider to see if we need to continue at this rate.

    05:34 Orders number two and three tell me exactly how long the healthcare provider wants that IV to continue.

    05:41 The second order for 8 hours and the third order says 125 mL an hour until 2 liters or 2000 milliliters have been infused into my patient.

    05:52 Now, let's talk about conversion drips to minute.

    05:55 Okay, so we've got normal saline at 125 mL an hour.

    06:00 Now, if you had a pump, you would just hang the bag, put the cartridge in the pump and you would set it to 125 mL per hour.

    06:09 The pump would make sure that that's the rate that it went.

    06:12 But we want you to be prepared in case there isn't a pump available.

    06:17 Now, you may think, “When would this happen?” It can happen in the hospital. It can happen in certain settings.

    06:23 It can also happen in the event of an emergency.

    06:26 So, you need to know how to be prepared how to do this.

    06:30 So we're going to tell you that no pump is available.

    06:32 So the rate must be converted to drops per minute, gtt, meaning drops per minute.

    06:39 Okay, so look at the IV tubing and note the drop factor.

    06:42 Well, we know how to do that.

    06:44 You see the big 10 there and it tells us 10 drops per milliliter.

    06:49 So we know that's what our drop factor is.

    06:51 This macroset is 10 drops per milliliter.

    06:55 So, we need to convert 125 milliliters an hour to drops per minute.

    About the Lecture

    The lecture IV Flow Rate Calculation (Nursing) by Rhonda Lawes is from the course Dosage Calculation (Nursing). It contains the following chapters:

    • IV Tubing Calibration
    • Macrodrip and Microdrip
    • IV Fluid Order Examples
    • Conversion to gtt/min

    Included Quiz Questions

    1. The tighter the roller clamp, the higher the pressure and the slower the drips
    2. The tighter the roller clamp, the lower the pressure and the faster the drips
    3. The looser the roller clamp, the higher the pressure and the slower the drips
    4. The looser the roller clamp, the lower the pressure and the slower the drips
    1. 6 hours
    2. 9 hours
    3. 15 hours
    4. 4 hours
    1. The nurse looks at the IV tubing to find the drop factor and then converts the rate of 125 mL/h to gtt/min.
    2. The nurse converts the rate of 125 gtt/min to the drop factor of 10 mL/h.
    3. The nurse opens the roller clamp halfway and checks the bag in half an hour to check how much fluid has infused
    4. The nurse alerts the HCP that there is no pump and it is therefore not safe to run the medication until a pump becomes available.

    Author of lecture IV Flow Rate Calculation (Nursing)

     Rhonda Lawes

    Rhonda Lawes

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