What Are Korotkoff Sounds?

Under normal circumstances, the movement of blood through the arm's artery is inaudible.
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  • Written By: Mary McMahon
  • Edited By: C. Wilborn
  • Last Modified Date: 21 November 2014
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Korotkoff sounds are distinctive sounds that can be distinguished when a blood pressure cuff is applied and adjusted. They were first described in 1905 by Russian physician Nikolai Korotkoff. Listening for these sounds with a stethoscope while using a blood pressure cuff allows a health practitioner to take a blood pressure reading. Many people are familiar with the process of manually taking blood pressure in clinical settings, as blood pressure is a vital sign commonly tested at doctor visits.

Under normal conditions, the movement of blood through the artery in the arm is not audible. This is because the flow of blood is not turbulent. In people with artery disease, sounds can be heard as the flow is disrupted. When a blood pressure cuff is applied, it disrupts the flow of blood in a stable and predictable fashion, and this can be used to generate information about the patient's blood pressure.

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When a blood pressure cuff is inflated above the systolic blood pressure, no sounds can be heard. The flow of blood is occluded and thus it is not moving through the artery in the arm at all. As pressure is lowered, the first phase of the Korotkoff sounds, a sharp tapping noise, is heard as the blood starts to woosh back into the artery. The reading on the cuff at this point is equal to the systolic blood pressure. As the pressure falls, the blood moves into the second stage, a swishing noise, followed by the third stage, characterized by pounding as blood moves through the vessel.

The fourth phase in the Korotkoff sounds is a blowing noise, followed by silence in the fifth phase as the pressure equals that of the diastolic pressure. The flow of blood returns to normal without the pressure of the blood pressure cuff, and silence resumes. A skilled practitioner can get an accurate blood pressure reading with one session, while others may take a second reading to confirm. Completely electronic blood pressure reading machines are programmed to listen for the Korotkoff sounds and take readings as appropriate.

Things which can interfere with the Korotkoff sounds can include placing the stethoscope improperly or being in a noisy environment. Patients also need to follow directives from the health care provider, including staying still and relaxed to avoid accidentally increasing their blood pressure. Talking or moving during the test can disrupt the readings and force the health care provider to repeat the test.

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Discuss this Article

anon329392
Post 4

@panda: Your heart is a bit weak. Just letting you know. D you have a tendency to faint? You say your normal blood pressure is pretty low? What is it?

billr
Post 3

When I was told that one shouldn't talk while using an automatic blood pressure reading machine, I thought -- mistakenly, according to the article -- that the "activity" of talking might raise one's actual blood pressure and thereby result in a too-high BP reading. It was very interesting to find out from this article the real reason for the "ban" on talking.

anon189506
Post 2

@panda2006: Make certain that there is a prominent note in your medical records that you have low blood pressure. The medical community can misunderstand your condition in an emergency or otherwise if that information is missing.

When I had an operation over 30 years ago, the nurses almost "called a code" on me because my normally low blood pressure was even lower in the middle of the night after the day of anesthesia and pain medications. I had to assure them that I would not be responding to them by conversation if I were in dire straits.

panda2006
Post 1

When doctors or nurses try to take my pulse or blood pressure on my wrist, they often have trouble hearing the sounds. I think this probably is because I have pretty low blood pressure, both naturally and even more now that I am a runner.Usually once they can find it, it's fine and I don't have any other signs of a serious problem, but it still can be a little creepy when someone at the doctor's office can't find my pulse.

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