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Blood pressure measurement

Definition

Blood pressure is a measurement of the force on the walls of your arteries as your heart pumps blood through your body.

You can measure your blood pressure at home. You can also have it checked at your health care provider's office, a fire station, or with blood pressure machines in drug stores and other places.

Alternative Names

Diastolic blood pressure; Systolic blood pressure; Blood pressure reading; Measuring blood pressure

How the Test is Performed

Sit in a chair with your back supported. Your legs should be uncrossed, and your feet on the floor.

Your arm should be supported so that your upper arm is at heart level. Roll up your sleeve so that your arm is bare.

You or your health care provider will wrap the blood pressure cuff snugly around your upper arm. The lower edge of the cuff should be 1 inch above the bend of your elbow.

  • The cuff will be inflated quickly. This is done either by pumping the squeeze bulb or pushing a button. You will feel tightness around your arm.
  • Next, the valve of the cuff is opened slightly, allowing the pressure to slowly fall.
  • As the pressure falls, the reading when the sound of blood 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 stops is recorded. This is the diastolic pressure.

Inflating the cuff too slowly or not inflating it to a high enough pressure may cause a false reading. If you loosen the valve too much, you will not be able to measure your blood pressure.

The procedure may be done two or more times.

How to Prepare for the Test

Before you measure your blood pressure:

  • Rest for at least 5 minutes before blood pressure is taken.
  • Do not take your blood pressure when you are under stress, have had caffeine or used a tobacco in the past 30 minutes, or have exercised recently.

Take two or three readings at a sitting. Take the readings 1 minute apart. Remain seated. When checking your blood pressure outside the doctor's office, note the time of the readings. Your health care provider may suggest that you do your readings at certain times.

  • You may want to take your blood pressure in the morning and at night for a week.
  • This will give you at least 12 readings and will help your health care provider make decisions about your blood pressure treatment.

How the Test will Feel

You will feel slight discomfort when the blood pressure cuff is inflated to its highest level.

Why the Test is Performed

High blood pressure has no symptoms so you may not know if you have this problem. High blood pressure is often discovered during a visit to the health care provider for another reason.

Finding high blood pressure and treating it early can help prevent heart disease, stroke, eye problems, or chronic kidney disease.

All adults should have their blood pressure checked regularly.

  • Get checked every 2 years if your blood pressure was less than 120/80 mm Hg at the most recent reading.
  • You should have it checked yearly if your last reading was 120 to 139/80 to 89 mm Hg.
  • People with high blood pressure, diabetes, heart disease, kidney problems, or other conditions should have blood pressure checked at least every year.

Normal Results

Blood pressure readings are usually given as two numbers. For example, your heath care provider might tell you that your blood pressure is 120 over 80 (written as 120/80 mm Hg). One or both of these numbers can be too high.

Normal blood pressure is when the top number (systolic blood pressure) is below 120 most of the time, and the bottom number (diastolic blood pressure) is below 80 most of the time (written as 120/80 mm Hg).

If your blood pressure numbers are 120/80 or higher but below 140/90, it is called pre-hypertension. If you have pre-hypertension, you are more likely to develop high blood pressure.

What Abnormal Results Mean

High blood pressure (hypertension) is when the top number (systolic blood pressure) is 140 or more most of the time or the bottom number (diastolic blood pressure) is 90 or more most of the time (written as 140/90 mm Hg).

If you have diabetes, heart disease, or kidney problems, or if you had a stroke, your heath care provider may want your blood pressure to be lower.

The most commonly used blood pressure targets for people with these medical problems are below 130 to 140/80 mmHg.

Most of the time, high blood pressure does not cause symptoms.

Considerations

It is normal for your blood pressure to vary at different times of the day:

  • It is usually higher when you are at work.
  • It drops slightly when you are at home.
  • It is usually lowest when you are sleeping.
  • It is normal for your blood pressure to increase suddenly when you wake up. In people with very high blood pressure, this is when they are most at risk of a heart attack and stroke.

Blood pressure readings taken at home may be a better measure of your current blood pressure than those taken at your doctor's office.

  • Make sure your home blood pressure monitor is accurate.
  • Ask your health care provider to compare your home readings with those taken in the office.

Many people get nervous at the health care provider's office and have higher readings than they have at home. This is called white coat hypertension. Home blood pressure readings can help detect this problem.

References

American Diabetes Association. Standards of medical care in diabetes -- 2014. Diabetes Care. 2014;37 Suppl 1:S14-S80.

Handler J, et al. 2014 evidence-based guideline for the management of high blood pressure in adults: report from the panel members appointed to the Eighth Joint National Committee (JNC 8). JAMA. 2014;311:507-520.

Peterson ED, Gaziano JM, Greenland P. Recommendations for treating hypertension: what are the right goals and purposes? JAMA. 2014;311:474-476.

Victor RG. Systemic hypertension: Mechanisms and diagnosis. In: Bonow RO, Mann DL, Zipes DP, Libby P, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 45.

Weber MA, Schiffrin EL, White WB, et al. Clinical practice guidelines for the management of hypertension in the community:a statement by the American Society of Hypertension and the International Society of Hypertension. J Hypertens. 2014;16:14-26.

Wright JT Jr, Fine LJ, Lackland DT, et al. Evidence supporting a systolic blood pressure goal of less than 150 mm hg in patients aged 60 years or older: the minority view. Ann Intern Med. 2014;160:499-503.


Review Date: 8/17/2014
Reviewed By: Linda J. Vorvick, MD, Medical Director and Director of Didactic Curriculum, MEDEX Northwest Division of Physician Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
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