Korotkoff Sounds [Explained]

In today’s micro-lecture, Australian Paramedical College Hon. Snr. Lecturer Sam Willis talks about Korotkoff Sounds; what they are, how they are heard and what this extremely complex image is telling us.

Today we are going to talk about Korotkoff sounds. Now, those of you who have attended Workshop 1 already, will already have heard about Korotkoff sounds. You may have even read about Korotkoff sounds in your studies. Or you may have already been really comfortable and familiar with Korotkoff sounds anyway through your own professional practice. What we’re going to do in this micro-lecture is talk about the sounds, what they are, how they’re heard, and what this extremely complex image is telling us.

Now, when you get to Workshop 1, you’re taught how to use blood pressure cuffs. If you’ve never done it before, it can be really complex. So you arrive at the workshops, and you’re taught all these wonderful skills. You’re taught how to put the blood pressure cuff on and how to get the patient comfortable and relaxed and pump it up and feel for a radial pulse and wait until the pulse goes away. At some point, you’re going to get your stethoscope out, and you’re going to place it onto the brachial artery, and you’re going to listen for Korotkoff sounds.

[01:04] Now, it’s the Korotkoff sounds that you’re hearing that actually determine the blood pressure. When we say to you, “Okay, can you go and demonstrate a blood pressure, please?” it’s actually the Korotkoff sounds that you’re listening for. You’re listening to the sounds that go …, …, …, and that’s the Korotkoff sound. What that is, it’s the sound of the turbulent blood flow as the valves are closing. You’re actually listening for the sound of the blood flow.

Now, we’ve got this complex picture in front of us. I’m not sure if any of you have seen anything similar in your reading, but let’s go through this together.

[01:45] Try and image the process of blood pressure. You put the cuff, you pump it up, and then you release the valve, and you have the stethoscope on the brachial artery. As you’re watching the needle going down like this, you’ll eventually see it start flicking. Then you’ll hear …, …, …, and that’s what you’re hearing right here at this point. So this is the pressure in the cuff.

[01:45] On this occasion, you pumped it up to 130. The cuff goes up to 300 mmHg. On this occasion, you pumped it up to 130. Then you release the pressure slowly, …, …, it’s really faint at this point. That’s just systolic blood pressure that you’re hearing just there. As you can see, it’s really faint; it’s really quiet.

As it comes down …, much louder …, …, …, …, then goes away again. As you can see here, the louder the sound is represented by the bigger the wave on here. Just because you’re not hearing it doesn’t mean it’s not occurring. As you let the air out of the cuff, the valves continue to open and close, and the blood is continuing to be turbulent. As you can see, it’s constant. It’s always there.

This line represents the pressure inside the cuff. You started off at about 130 according to this image. There’s actually for it. Then as you release the air, release the pressure, you start to hear to Korotkoff sounds.

The take-home message for this is you do need to know the process. You will be taught the process when you get into the workshop. Then, as you start to hear the Korotkoff sounds, they are very quiet. Then they get louder. The first really, really quiet one is the systolic blood pressure. The very, very last quiet one is the diastolic blood pressure. Of course, you guys can read about all of this in your own time prior to getting to the workshop.

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