The mercury sphygmomanometer has always been regarded as the gold standard for clinical measurement of blood pressure, The mercury sphygmomanometer combined with an inflated cuff and auscultation remains the gold standard for the measurement of blood pressure in children.
The device consists of a mercury manometer in which mercury rises to a certain height in response to blood pressure. … Hence mercury is used as a standard fluid in blood measurement and other pressure measurement devices.
How To Use a Sphygmomanometer
- To begin blood pressure measurement, use a properly sized blood pressure cuff. The length of the cuff’s bladder should be at least equal to 80% of the circumference of the upper arm.
- Wrap the cuff around the upper arm with the cuff’s lower edge one inch above the antecubital fossa.
- Lightly press the stethoscope’s bell over the brachial artery just below the cuff’s edge. Some health care workers have difficulty using the bell in the antecubital fossa, so we suggest using the bell or the diaphragm to measure the blood pressure.
- Rapidly inflate the cuff to 180mmHg. Release air from the cuff at a moderate rate (3mm/sec).
- Listen with the stethoscope and simultaneously observe the dial or mercury gauge. The first knocking sound (Korotkoff) is the subject’s systolic pressure. When the knocking sound disappears, that is the diastolic pressure (such as 120/80).
- Record the pressure in both arms and note the difference; also record the subject’s position (supine), which arm was used, and the cuff size (small, standard or large adult cuff).
- If the subject’s pressure is elevated, measure blood pressure two additional times, waiting a few minutes between measurements.