What is blood pressure?

Blood pressure is the force of blood against the walls of arteries. Blood pressure is recorded as two numbers - the systolic pressure (as the heart beats) and the diastolic pressure (as the heart relaxes between beats). The measurements are written one above or before the other, with the systolic number on top and the diastolic number on the bottom. For example, a blood pressure measurement of 120/80 mm Hg (millimeters of mercury) is called "120 over 80."

A new category called prehypertension serves as a warning to people with higher than normal blood pressure not yet considered high enough for medication. People with 120 to 139 over 90 are in this category, which means they should exercise and eat a balanced, low-fat diet. Normal blood pressure is 119 or lower and 79 or below.

What is high blood pressure?

Blood pressure normally rises and falls during the day. When blood pressure is consistently elevated, it is called high blood pressure, or hypertension. A consistent blood pressure reading of 140/90 mm Hg or higher is considered high blood pressure.

In most instances, high blood pressure does not have symptoms. So the only way to detect it is to have your blood pressure checked regularly.

Why is high blood pressure a concern?

Over time, high blood pressure can damage your arteries and lead to serious health problems. High blood pressure increases your chance (or risk) for getting heart disease and/or kidney disease, and for having a stroke. Hypertension is especially dangerous because it often has no warning signs or symptoms. Regardless of race, age, or gender, anyone can develop high blood pressure. It is estimated that one in every four American adults has high blood pressure. Once high blood pressure develops, it usually lasts a lifetime.

How is blood pressure measured?

Your health care provider uses a device called a sphygmomanometer (sfig'-mo-ma-nom-e-ter). A cuff is wrapped around your upper arm. Then a pump inflates the cuff to put pressure on your arteries. As the cuff is slowly deflated, a stethoscope is used to hear the sounds of the blood rushing back through the artery. Blood pressure is measured as the numbers on the dial when two different sounds are heard. A manual sphygmomanometer is pictured below:

Some blood pressure testing devices use electronic instruments or digital readouts. In these cases, the blood pressure reading appears on a small screen or is signaled in beeps, and no stethoscope is used.

Blood pressure varies during the course of the day, depending on your activity level and even your emotional state. Blood pressure is lower during sleep and usually rises during exercise.

How can I take my own blood pressure?

Tests at home can be done with the familiar blood pressure cuff and a stethoscope, or with an electronic monitor, such as a digital readout monitor. Be sure that the person who uses the device reads the instructions before taking blood pressure readings. Your doctor, nurse or pharmacist can help you check the device and teach you how to use it. You also may ask for their help in choosing the best one for you. Blood pressure devices can be bought at various places, such as discount chain stores and pharmacies.

How do I prepare for a blood pressure test?

• Don't drink coffee or smoke cigarettes 30 minutes before having your blood pressure measured.
• Before the test, sit for five minutes with your back supported and your feet flat on the ground. Rest your arm on a table at the level of your heart.
• Wear short sleeves so your arm is exposed.
• Go to the bathroom prior to the reading. A full bladder can change your blood pressure reading.
• Have two readings, taken at least two minutes apart, and average the results.
• Ask the doctor or nurse to tell you the blood pressure reading in numbers.