Quality of Korotkoff sounds: bell vs diaphragm, cubital fossa vs brachial artery

Comparison of clarity of Korotkoff sounds was made between those heard with the bell or diaphragm of the stethoscope and between those heard over the cubital fossa or more proximally and medially over the maximal brachial artery pulse--during indirect sphygmomanometry. Multiple measurements were made by two trained technicians on 48 supine adults. The measurements were balanced as to stethoscope-head/arm-placement combinations, stethoscope used, control of the pressure bulb, and use of right or left arm. The Korotkoff sounds were heard better with the bell of the stethoscope placed over the brachial artery pulse (BB) than with the diaphragm placed over the cubital fossa (DC). The former combination (BB) gave significantly higher blood pressure estimates for systolic blood pressure and fourth phase diastolic blood pressure than the latter combination (DC).