Case Study: Calculate the Flow Rate (Nursing)

by Rhonda Lawes

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    00:01 Now let's talk about conversion drips two minute.

    00:04 Okay, so we've got normal saline at 125 mils an hour.

    00:09 If you had a pump, you would just hang the bag, put the cartridge in, in the pump, and you would set it to 125 mils per hour.

    00:18 And the pump would make sure that that's the rate that it went.

    00:21 But we're going to, we want you to be prepared in case there isn't a pump available.

    00:26 Now you may think when would this happen, it can happen in the hospital, it can happen in certain settings, and it can also happen in the event of an emergency.

    00:35 So you need to know how to be prepared how to do this.

    00:38 So we're going to tell you that no pump is available, so the rate must be converted to drops per minute gtt, meaning drops per minute.

    00:48 Okay, so look at the IV tubing and note the drop factor.

    00:51 Well we know how to do that.

    00:52 You see the big 10 there and it tells us 10 drops per millilitre.

    00:57 Okay, so we know that's what our drop factor is.

    01:00 This macro set is 10 drops per millilitre.

    01:04 So we need to convert 125 millilitres in our two drops per minute.

    01:10 Okay, you with us? Let's keep going.

    01:14 Okay, so we've got an IV ordered to infuse at a rate of 125 mL an hour using an IV tubing set that is 10 drops (gtt), 10 drops per milliliter.

    01:26 Calculate the drip rate, the flow rate.

    01:29 Okay, so we're going to calculate the drips per minute by calculating how many milliliters per minute.

    01:36 It's telling us 125 milliliters an hour.

    01:40 Well, let's divide 125 by 60.

    01:44 So, we're going to come up with roughly 2.

    01:46 Now, wait a minute.

    01:47 I know that 125 divided by 60 isn't a perfect 2.

    01:53 But remember, we're doing this manually.

    01:55 We're counting drops.

    01:56 I can only count whole drops.

    01:59 So you're going to want to be very careful and know that I can't give 2 point "drrt" drops a minute.

    02:05 When I'm counting it using only my eyes, I can only count whole numbers of drops.

    02:10 I can't count 2 ½ drops.

    02:12 I can't count 2.26 drops.

    02:15 I can only count 2 or 3.

    02:18 But since I've divided this 125 by 60, I know I'm going to go for 2 milliliters a minute.

    02:25 Okay, so you're going to calculate the drips per minute by calculating how many mL per minute, right? So, we've got 125 divided by 60.

    02:33 We're all on the same page on why we can go with 2, even though we know there's a little bit of that after the decimal point.

    02:39 The IV fluid will have to flow 2 milliliters in every minute to infuse 125 milliliters in an hour.

    02:48 Okay, so you still with us? Great.

    02:51 You understand why we're using 2 milliliters a minute because we want to give 125 milliliters in an hour.

    02:58 Next step, let's calculate the drops per minute in order to get 2 milliliters in every minute.

    03:06 Well, we know there are 10 drops in every milliliter, right? That's what the tubing set tells us.

    03:11 It takes 10 drops, One, two, three, four, five, six, seven, eight, nine, ten, to equal 1 milliliter.

    03:19 So, if I know 10 drops in 1 milliliter, I need to know how many drops are in 2 milliliters.

    03:25 Hey, even if you can already do the math in your head, don't, because I want to use this simple example as a formula.

    03:31 The next step would be to cross multiply, right, 1 times X and 10 times 2.

    03:38 Now, I have 1X equals 20.

    03:42 So, X equals 20.

    03:46 So, I know that I need 20 drops a minute in order for me to have 125 milliliters an hour.

    03:54 Okay.

    03:54 So, let's go back through that just to make sure.

    03:57 We've got to figure out the drops per minute.

    04:00 We looked at the tubing, 10 drops in a mL.

    04:04 And then, so how many drops will it take me to have, to make in a minute have 2 milliliters? That's why we cross multiply, 20 equals X.

    04:14 So I need 20 drops a minute in order to turn this into a rate.

    04:19 Okay, so the IV fluid will flow 20 drops every minute in order to infuse 125 milliliters in an hour.

    04:30 So, count the drops in the fluid chamber and adjust the roller clamp until you get 20 a minute.

    04:35 Now, this is not a perfect science.

    04:37 It takes some practice.

    04:38 You're going to have to practice counting.

    04:41 You're going to need to have some type of watch with a second hand.

    04:44 You're going to have to work with your dexterity enforcing that roller clamp back and down.

    04:49 Now, we don't recommend that you stand there for 60 seconds and count the drops, right? What you want to do is count for 15 or 20 seconds and then multiply it by 3 or 4.

    05:00 That will tell you what you'd have for a minute.

    05:03 So, you look at that chamber for a full 15 or 20 seconds.

    05:07 When you have that number, you multiply it to equals 60 seconds.

    05:11 That will tell you what your rate is a minute.

    05:14 Remember, our goal is to adjust the chamber so that we have 20 drops a minute in order to get the 125 milliliters in, in an hour.

    About the Lecture

    The lecture Case Study: Calculate the Flow Rate (Nursing) by Rhonda Lawes is from the course Dosage Calculation (Nursing).

    Included Quiz Questions

    1. 4 mL/min
    2. 2 mL/min
    3. 25 mL/min
    4. 5 mL/min
    1. 60 gtt/min
    2. 40 gtt/min
    3. 25 gtt/min
    4. 16.7 gtt/min
    1. Watch the drips for 15 seconds to get the rate and multiply that number by 4 to determine the rate/min.
    2. Watch the drips for a full 60 seconds to determine the rate/min.
    3. Adjust the roller clamp by feel; it is not necessary to count the drips.
    4. Call the HCP to get an accurate rate/min flow because it is not safe practice to count it manually.

    Author of lecture Case Study: Calculate the Flow Rate (Nursing)

     Rhonda Lawes

    Rhonda Lawes

    Customer reviews

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    Best explanation! Makes it so simple
    By Johanna M. on 23. March 2021 for Case Study: Calculate the Flow Rate (Nursing)

    This is terrific. I really like how Professor Lawes breaks things down.