| Subject | Contents |
| Definition | Blood pressure is a measurement of the force applied against the walls of the arteries as the heart pumps blood through the body. The pressure is determined by the force and amount of blood pumped and the size and flexibility of the arteries. The blood pressure is continually changing depending on activity, temperature, diet, emotional state, posture, physical state, and drugs. |
| Alternative Names | Diastolic blood pressure; Systolic BP; BP; Diastolic BP; Systolic blood pressure |
| How the test is performed | The blood pressure is usually taken while the person is seated with the arm resting on a table and slightly bent so that the arm is at the same level as the heart. The upper arm needs to be bare (with the sleeves rolled up, but not tight or uncomfortable). Blood pressure readings are usually given as two numbers: for example, 110 over 70 (written as 110/70). The first number is called the "systolic blood pressure" reading, and it represents the maximum pressure exerted when the heart contracts. The second number (the lower number) is called the "diastolic blood pressure" reading, and it represents the pressure in the arteries when the heart is at rest. To perform the blood pressure measurement, the blood pressure cuff is wrapped snugly around the upper arm and positioned so that the lower edge of the cuff is 1 inch above the bend of the elbow. The large artery on the inside of the elbow is located by feeling for the pulse . The ear piece of the stethoscope is placed in the ears, and the head of the stethoscope is placed over the artery below the cuff. It should not rub the cuff or any clothing because it can make noises that will block out the pulse sounds. Correct positioning of the stethoscope is important to get an accurate recording. The valve on the rubber inflating bulb is closed. The bulb is squeezed rapidly to inflate the cuff until the dial or column of mercury reads 30 mm Hg (millimeters of mercury ) higher than the usual systolic pressure. If the usual systolic pressure is unknown, inflate to 210 mm Hg. Now the valve is opened slightly, allowing the pressure to fall gradually (2 to 3 mm Hg per second). As the pressure falls, the level on the dial or mercury tube at which the pulsing is first heard is recorded. This is the systolic pressure. As the air continues to be let out, the sounds will disappear. The point at which the sound disappears is recorded. This is the diastolic pressure (the lowest amount of pressure in the arteries as the heart rests). The procedure may be repeated 2 or more times. |
| How to prepare for the test | The test can be done at any time. When it is performed for comparison purposes, it is usually done after resting for at least 5 minutes. One needs to have a blood pressure cuff and a device for detecting the pulse in the artery (stethoscope or microphone). Infants and children: The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age: Infant test or procedure preparation (birth to 1 year) Toddler test or procedure preparation (1 to 3 years) Preschooler test or procedure preparation (3 to 6 years) Schoolage test or procedure preparation (6 to 12 years) adolescent test or procedure preparation (12 to 18 years) |
| How the test will feel | The pressure of the cuff on the arm is felt. |
| Why the test is performed | Most people cannot sense if their blood pressure is high ( hypertension ) because there are usually no symptoms. High blood pressure increases the risk of heart failure , heart attack , stroke , and kidney failure . For people who have high blood pressure, it is a way of monitoring the effectiveness of medications and dietary modifications on the blood pressure. |
| Normal Values | Generally, in adults, the systolic pressure is approximately 120 mm Hg, and the diastolic pressure is approximately 70 to 80 mm Hg. |
| What abnormal results mean | Mild hypertension : diastolic pressure consistently 90 to 104 mm Hg, or systolic pressure from 145-159 mm Hg Significant hypertension: systolic pressure above 160 mm Hg or diastolic pressure above 100 mm Hg Hypotension : blood pressure below normal
Blood pressure readings may be affected by many different conditions, including:
Cardiovascular disorders Neurological conditions Kidney and urological disorders Pre-eclampsia in pregnant women Psychological factors such as stress , anger, or fear Various medications |
| What the risks are | There is no risk to checking blood pressure. |
| Special considerations | Consult the health care provider if the measurements are consistently high or low, or if the symptoms are present at the same time as the high or low reading. Repeated measurements are important for screening or monitoring. A single high measurement does not necessarily mean hypertension . A single normal measurement does not necessarily mean that high blood pressure is not present. |
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