Mastering Korotkoff Sounds: A Beginner’s Guide.

"Educational chart for nursing students showing the 5 phases of Korotkoff sounds. It features a vertical blood pressure gauge on the left and sound wave visualizations for each phase. Phase 1 shows sharp spikes for tapping; Phase 2 shows fuzzy waves for swishing; Phase 3 shows large bold spikes for crisp knocking; Phase 4 shows small rounded bumps for muffling; and Phase 5 shows a flat line for silence."

Mastering Korotkoff Sounds: A Beginner’s Guide.

You’ve wrapped the cuff, placed your stethoscope, and opened the valve—but then you hear a series of thumps, swishes, and mumbles. What exactly are you listening for?

These sounds are called Korotkoff sounds, named after Dr. Nikolai Korotkoff. They aren't actually the sound of the heart beating; they are the sounds of blood flow becoming "turbulent" as it pushes through an artery that is being squeezed by a blood pressure cuff.

Here is your phase-by-phase guide to mastering the sounds of the brachial artery.

The Five Phases of Korotkoff Sounds

Understanding the "rhythm" of these phases will help you identify the Systolic and Diastolic numbers with much higher confidence.

Phase I: The Clear Tapping (Systolic Pressure).

The Sound: A clear, rhythmic tapping sound that gradually increases in intensity.

The Clinical Goal: The very first tapping sound you hear is your Systolic Pressure.

Pro Tip: Look for the start of a consistent rhythm. A single "stray" click caused by the patient moving shouldn't be counted as the systolic reading.

Phase II: The Swishing Sound.

The Sound: The taps become softer and take on a "whooshing" or swishing quality.

Why it happens: The artery is opening further, allowing more blood to flow, which creates turbulent murmurs.

Note: If you have a low-quality stethoscope, this phase can sometimes be hard to hear in a noisy room.

Phase III: The Crisp Knocking.

The Sound: The sounds become louder and much crisper again, almost like a distinct "knocking" on a door.

Why it happens: The artery is now remaining open for a longer portion of the cycle, but there is still enough cuff pressure to create a loud "slap" of blood against the vessel walls.

Phase IV: The Muffling.

The Sound: A sudden change in quality where the crisp knocks become muffled, dull, or "soft." It sounds like someone put a pillow over the sound.

Note: In some patients (like children or high-output athletes), the sounds never fully disappear. In those cases, Phase IV is used as the diastolic reading.

Phase V: Silence (Diastolic Pressure).

The Sound: This isn't a sound—it is the point where all sounds disappear completely.

The Clinical Goal: The last sound you hear before the silence is your Diastolic Pressure.

Quick Tips for "Difficult to Hear" Patients.

If you are struggling to hear these phases, try these three "Nurse Hacks":

Check your Diaphragm: Ensure the flat side of your stethoscope is directly over the brachial artery (medial side of the antecubital space).

Raise the Arm: Have the patient raise their arm before inflation to drain venous blood; this makes the contrast of the Korotkoff sounds sharper.

Quiet the Room: Even a humming air conditioner or a TV in the background can mask Phase IV and V.

What to "Watch" For (Visual Cues).

While you should always rely on your ears, watch the needle on the manual gauge (sphygmomanometer). You will often see the needle flicker or bounce in sync with Phase I and Phase III. This is a great visual "warning" that a sound is about to occur!

Read More about BP Measurements: Easy Step-by-Step Guide for Learner Nurses.