American Diagnostic Corporation (ADC) ADview Modular Diagnostic Station - Manual (Page 33)

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K-Sounds: A Primer
Korotkoff sounds, commonly called K-sounds, are the sounds you detect through your stethoscope when
you measure blood pressure with a sphygmomanometer or an aneroid device. Named for the Russian
physician who identified them, there are five phases of K-sounds, each phase characterized by a distinct
volume and quality of sound.
K-sounds are heard through the stethoscope as the blood pressure cuff deflates. The first sound, K-1, is
heard when cuff pressure equals systolic pressure. K-1 is a sharp, tapping sound.
The K-2 phase is characterized by a swishing sound, caused by the swirling currents in the blood as the
flow through the artery increases.
In the K-3 phase, there is a resumption of crisp tapping sounds, similar to those heard during phase 1.
An abrupt muffling of sound identifies K-4, the fourth phase.
The end or fifth phase is the point at which sounds cease to be heard altogether.
Systolic pressure is registered at K-1 and diastolic at K-5.
K-4 or K-5? There exists some debate about whether K-4 or K-5 should be recorded
as the diastolic BP. In most cases, K-5 is preferred. However, if the sound persists even
after the cuff is completely deflated, it is recommended that K-4 be recorded as the
diastolic blood pressure.
2
You can find more tips like this in the British Hypertension Society’s current
guidelines for management of hypertension.
2 B Williams, NR Poulter, MJ Brown, M Davis, GT McInnes, JF Potter, PS Sever, S McG Thom, British
Hypertension Society Guidelines, Guidelines for management of hypertension: report of the fourth working
party of the British Hypertension Society 2004 – BHS IV, Journal of Human Hypertension, 2004 18, 139-
185.