An instrument for measuring blood pressure in the arteries, especially one consisting of a pressure gauge and a rubber cuff that wraps around the upper arm and inflates to constrict the arteries.
A sphygmomanometer (often condensed to sphygmometer) or blood pressure meter is a device used to measure blood pressure, comprising an inflatable cuff to restrict blood flow, and a mercury or electronic manometer to measure the pressure. The pressure is stated as two numbers, the highest pressure that blood reaches (pushes past the cuff) and the lowest (the flow is unimpeded and flows without being pushed by the heart contraction). Manual sphygmomanometers are used in conjunction with a stethoscope to determine the two pressures.
The higher pressure is the systolic (heart pushing), the lower the diastolic. Blood pressure is stated as both of these numbers, e.g. 115/75 spoken "115 over 75" is a systolic pressure of 115 (mm Hg), a diastolic of 75 (mm Hg).
The patient may either be in a lying position or be comfortably seated. The patient should be placed at ease and time should be allowed for recovery from any unusual recent exercise or apprehension. Blood pressure determination should not be made after recent meals. The arm should be bared and care should be taken to avoid any constriction of the arm by clothing or other interfering articles. The arm should then be slightly flexed and relaxed. In the sitting position the forearm should be supported at heart level on a smooth surface. The hand may be pronated or supinated, depending upon which position is found to yield the clearest sounds.
SYSTOLIC: A stethoscope receiver should be applied snugly over the artery in the antecubital space, free from contact with the cuff. The pressure in the sphygmomanometer should then be raised rapidly and decreased slowly as in the palpatory method, until a sound is heard with each heartbeat. Note the reading as systolic pressure.
DIASTOLIC: with continued deflation of the system below systolic pressure at a rate of 2 to 3 mmHg per heartbeat, the sounds undergo changes in intensity and quality. As the cuff pressure approaches diastolic, the sounds often become dull and muffled quite suddenly and finally cease. The point of cessation is the best index of diastolic pressure.