Korotkoff sounds

During an emergency in the hospital you are evacuated with an anaesthetised patient

into the hospital car park. You want to measure the patient’s blood pressure and are

handed a stethoscope and a sphygmomanometer. What sounds on auscultation would

you use to identify the systolic and diastolic blood pressure?

a) The peak of the first Korotkoff sound and the muffling of the fourth Korotkoff sound

b) The start of the first Korotkoff sound and the start of the fifth Korotkoff sound

c) The start of the first Korotkoff sound and the muffling of the fourth Korotkoff sound

d) The peak of the first Korotkoff sound and the peak of the fifth Korotkoff sound

e) The start of the first Korotkoff sound and the peak of the fifth Korotkoff sound

Answer: B

Explanation

In these days of non-invasive blood pressure monitoring with machines, the older

skills of measuring blood pressure in a way that uses no electricity may seem irrelevant.

Equipment malfunction, power failure, or remote anaesthesia are circumstances

where the technique is still necessary thus knowledge of it is core. Judging by recent

short answer questions set for the Final FRCA, the College shares this opinion.

The five Korotkoff sounds are heard as the sphygmomanometer cuff is deflated

from a pressure above systolic. The first sound is the snapping sound first heard, the

second is quieter murmurs, the third is a snapping sound, the fourth is thumping or

muting of the sound and the fifth is the onset of silence. Traditionally systolic pressure

has been measured at the onset of the first sound and diastolic has been at the last

audible point of the fourth sound (muffling). Since 2000, there has been a change over

to using the start of the fifth Korotkoff sound as diastolic pressure as this was thought

to be more reproducible between different operators as it was a quantitative assessment

rather than a qualitative one. Some have argued that, sometimes, the fourth

sound never disappears. The cause for this is thought to usually be excessive pressure

on the head of the stethoscope, and a lighter touch is recommended.