sphygmomanometer

sphygmomanometer Blood pressure cuff, an instrument for measuring blood pressure, particularly in arteries. Digital and manual models are available. The two basic types of manual sphygmomanometers are the mercury column and the gauge with a dial face. The manual sphygmomanometer in most frequent use today consists of a gauge attached to a rubber cuff that is wrapped around the upper arm and is inflated to constrict the arteries. A blood pressure reading consists of two numbers: systolic and diastolic. Systolic refers to systole, the phase when the heart pumps blood out into the aorta. Diastolic refers to diastole, the resting period when the heart refills with blood. At each heartbeat, the blood pressure is raised to the systolic level, and, between beats, it drops to the diastolic level. With the cuff inflated with air, a stethoscope is placed over an artery (the brachial artery) in the crook of the arm. As the air in the cuff is released, the pressure reading when the first sound is heard through the stethoscope marks the systolic pressure. As the release of air from the cuff continues, a point is reached when the sound diminishes and then is no longer heard. The pressure at which the last sound is heard marks the diastolic pressure. The blood pressure reading might show the systolic and diastolic pressures to be, for example, 120 and 78mm of mercury (Hg), respectively. This is usually written 120/78 and said to be “120 over 78.” Blood pressure readings vary depending on age and many other factors. Children and adults with smalleror larger-than-average-sized arms may need specialsized pressure cuffs. See also blood pressure; hypertension; hypotension.