Systolic Pressure and Diastolic Pressure (Nursing)

by Rhonda Lawes, PhD, RN

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    00:02 Now, we know how to get an accurate systolic and diastolic pressure, because we use that blood pressure cuff with a sphygmomanometer to measure these 2 pressures.

    00:13 Now, I want to talk to you about what is the difference between systolic and diastolic? Systolic pressure is the number that's listed on the top.

    00:22 Diastolic pressure is the number that's listed on the bottom.

    00:25 So when you see a normal blood pressure reading, you'll see the number like, for example, the perfect blood pressure, 120/…we call that over…the number 80.

    00:36 So that's the systolic pressure over the diastolic pressure.

    00:40 Now, let's talk about how those pressures are different.

    00:43 The systolic pressure is the measurement of the force of blood pumping out of the heart into the arteries.

    00:50 So, for lack of a better model, right now, I'm going to use my hand and you pretend that this is a heart.

    00:56 So this is systolic pressure, my heart is contracting.

    01:00 That's what systolic pressure is.

    01:02 This is when it's working the hardest, and that's the measurement of the force as the blood pumps out of the heart and into the arteries, right? So systolic, systolic, systolic, systolic.

    01:17 Now, diastolic is the blood pressure measurement of the heart as it can…rests, okay? So, systolic, diastolic, systolic, diastolic, systolic, diastolic.

    01:30 It's when the…in between the heartbeats.

    01:33 This is…pushing blood out to the rest of the body.

    01:36 This…is the heart getting its blood supply.

    01:40 Blood out to the rest of the body… Heart getting its blood supply.

    01:45 Systolic, diastolic, systolic, diastolic, systolic, diastolic.

    01:51 I know that's probably kind of annoying by this point, but I want you to be very solid on what is the difference between that top number and the bottom number? The top number in a blood pressure reading is a systolic pressure; this.

    02:05 The bottom number of the reading is the diastolic pressure; this.

    02:09 So, when does my heart get its perfusion of oxygen, here or here? Now, you see me using my hand, but actually, that's a really good way to trigger and focus your brain.

    02:20 So, wherever you are and you're watching this video, I want you to stop for a minute and just think about that; systolic… No, no, I mean, not just think about it, actually use your hand.

    02:30 Systolic, diastolic systolic, diastolic, systolic, diastolic.

    02:36 Now you know why those 2 pressures are so important, and why we get really concerned about that diastolic pressure being elevated, because we know the heart is really taking a hit during that.

    02:49 Okay.

    02:50 Now, when you actually take a blood pressure, this is kind of cool.

    02:52 So, look at this first picture.

    02:54 You see the 120/80, there.

    02:57 That's systolic pressure over diastolic pressure.

    03:00 Systolic pressure of 120, diastolic pressure of 80.

    03:05 You got a normal blood flow in the arm.

    03:07 You've asked the patient if they've exercised, drank caffeine or alcohol, or smoked 30 minutes before the test.

    03:14 They've had their arm resting comfortably.

    03:16 They waited 5 minutes.

    03:17 You have the appropriate size cuff on their arm.

    03:20 It's above the bend in their elbow, and we're ready to take their blood pressure.

    03:23 Now, you see in the drawing you have normal blood flow.

    03:26 There's no occlusion of blood flow before we inflate the cuff.

    03:31 Now when you inflate the cuff, now you can see in the picture, that's a manual one where you have to… you have to turn the screw to close it off, and then squeeze the bulb to press it, and that will fill the cuff up with air until it occludes that artery.

    03:45 That's what we're looking at doing.

    03:46 So the cuff pressure blocks off the blood flow.

    03:49 So now while you have the cuff on the patient, there, the rest of their arm is not being perfused which is why you want to be efficient when you take their blood pressure.

    03:59 It can be somewhat uncomfortable for your patient.

    04:02 Now, when you're in nursing lab, they'll go over very specific steps with you on how you listen and when you listen.

    04:08 We're just kind of giving you a quick overview of these different pressures.

    04:12 So, now, the systolic pressure equals the cuff pressure.

    04:15 So, when you place your stethoscope here on the place that you assessed, when you put your stethoscope there, we're listening for the first beat, right? The first time we can hear that…love dub, or as they say in Germany, boom, boom, when you hear that first, that's the systolic pressure, the systolic pressure.

    04:36 In the example of 120/80, that's going to be the systolic pressure.

    04:41 Now you listen until it disappears or gets extremely muffled.

    04:45 That is the diastolic pressure.

    04:48 So, as you're taking a patient's blood pressure, just be aware of what those numbers and sounds mean.

    04:54 And make sure that you… make sure you deflate that cuff completely and let that blood flow return to the patient.

    05:01 Because you've completely occluded the blood flow when you take a blood pressure, it's not a good idea to go, "Argh, that didn't work." Pump it up right away.

    05:09 You want to give that arm time to really rest and to really fill back up again.

    05:14 So, don't take measurements repeated right after each other.

    05:17 Make sure you have several minutes in between blood pressure measurements.

    05:20 Anytime you question a measurement, recheck it.

    05:23 That's always a really good idea.

    05:25 Ask the patient if they know what their normal blood pressure is.

    05:28 If you're reading seems significantly different than what their normal is, note their other vital signs and see if you can start to problem solve as to what might possibly be the cause.

    05:39 You know, if I have somebody come in and their normal blood pressure is 118/90, and all of a sudden, they're at 98/70, and their heart rate's going really fast, my first worry is going to be, "I wonder if there dehydrated." Because when they have lower volume…oh, I've got lower volume, so I have a lower cardiac output.

    06:00 So what the heart does is, "Whoa, I've got less volume to push around," so it speeds up.

    06:04 It tries to go faster.

    06:05 It tries to move around whatever little volume it has much faster.

    06:08 So if I've got somebody who's got a significant drop in their blood pressure, I suspect that they have lower volume on board and their heart rate is up.

    06:17 Those are all signs that my patient might be hypovolemic or low on volume.

    06:23 Now, we'll delve more into that when we talk about the IV video, so you want to check that one out because we can talk about how IV fluids really impact fluid volume.

    About the Lecture

    The lecture Systolic Pressure and Diastolic Pressure (Nursing) by Rhonda Lawes, PhD, RN is from the course Pharmacology and Implications for Nursing.

    Included Quiz Questions

    1. Systolic
    2. Diastolic
    3. Mean
    4. Ventricular
    5. Venous
    1. Diastolic
    2. Systolic
    3. Mean
    4. Central venous
    1. Recheck the measurement after a few minutes
    2. Call the health care provider immediately
    3. Ask the client to stand up and take a new reading
    4. Wait for one hour and take a new measurement
    1. Low blood volume
    2. High blood volume
    3. Low blood pressure
    4. High blood pressure

    Author of lecture Systolic Pressure and Diastolic Pressure (Nursing)

     Rhonda Lawes, PhD, RN

    Rhonda Lawes, PhD, RN

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    By Irina P. on 20. March 2021 for Systolic Pressure and Diastolic Pressure (Nursing)

    Thank you very much for your detailed and interesting explanation of the learning material! The way you present your lecture helps to remember it!