The Phases

Korotkoff sounds are the distinct sounds you hear when listening for blood pressure measurements with a sphygmomanometer and stethoscope. As the cuff slowly deflates blood starts to flow through the brachial artery making different sounds. These sounds happen in five phases and help us to determine the systolic and diastolic numbers, offering vital insight into cardiovascular health.

NOTE: these audio recordings have been enhanced and repeated to be heard without a stethoscope. The exaggerated sound you hear in these recordings might not reflect the exact sound you hear when taking a manual blood pressure.

Phase I (k-1)

The First Sound - This is the moment you first hear a clear, sharp tapping sound as the cuff deflates. it marks the return of blood flow through the artery. This sound tells you the systolic pressure . The systolic pressure is the pressure in the arteries when the heart is actively pumping. It is the top number in a blood pressure reading.

The Wooshing/Swishing Sound - The tapping fades into a Swishing, Wooshing noise. This happens as the blood flows through the artery as the cuff deflates.

Phase II (k-2)

Phase III (k-3 )

The Thump - Phase three introduces intense thumping sounds that are softer than phase 1. As the blood flows through the artery, the cuff pressure is still inflated to obstuct the blood flow.

Phase IV (k-4)

The muffling of sound - After phase three, the thumping gets softer as the pressure from the cuff is being released. This is called the first diastolic reading.

Phase V (k-5)

Silence - This is the phase where the blood pressure cuff has been released enough to allow normal blood flow. All sound disappears and there is only silence. This is known as the second diastolic reading and is recorded as the diastolic (bottom number) on the recorded blood pressure.