What Is High Blood Pressure? |
|
|
|
|
||
|
Blood pressure is expressed as the relationship between two types of pressure: systolic and diastolic. Systolic pressure is the pressure exerted when your heart beats and forces the blood through the arteries. Diastolic pressure is the pressure between heartbeats. We express blood pressure as the ratio of these two numbers, with systolic over diastolic. Both numbers are expressed in millimeters of mercury, and systolic pressure should be about forty millimeters higher than diastolic pressure. For example, my blood pressure is usually 105 systolic and 65 diastolic. I would write it simply as 105/65 or say it as "one- oh-five over sixty-five."
Blood pressure is measured with a sphygmomanometer, a big word for a simple device. It consists of three parts: the cuff a device to detect sound, and a pressure sensor. The cuff goes around your arm and is pumped full of air so it stops the blood flow. The cuff is hooked to a column of mercury or a pressure sensor that shows the pressure inside the cuff The nurse puts a stethoscope or other listening device just below the cuff to listen for specific sounds, known as the Korotkoff sounds. The nurse slowly releases the cuff pressure and listens. At first, because the cuff is tight, she hears nothing. Then she slowly releases the cuff pressure and hears thump-thump-thump. This thumping is the heart pushing blood past the cuff with each beat, and the pressure at this point is the systolic pressure. Cuff pressure is allowed to fall just until these thumps are replaced by a steady whooshing sound. Pressure at the instant the whoosh appears is the diastolic pressure.
You can purchase a device that measures blood pressure electronically. Electronic sphygmomanometers are available in drugstores and by mail order. They usually have a cuff that fits on the arm, which contains a sensitive listening device, so you only need to pump up the cuff and the instrument does the rest. In fact, some of them even pump up the cuff for you! Others use your thumb to take the measurements, and some have a digital readout of systolic pressure, diastolic pressure, and pulse rate.
|
||