How to Buy a Blood Pressure Monitor

The importance of home blood pressure monitoring

High blood pressure (hypertension) affects more than 900 million people worldwide and is one of the leading causes of death from cardiovascular disease. Research indicates that at-home self-measurement is beneficial in several ways:

• It provides more blood pressure measurements within a limited period.
• It serves as an incentive when you can see results immediately and have more control over your treatment.
• Keeping a log of measurements can assist your healthcare provider when adjusting your medication(s) and diagnosing and preventing problems.
• Being able to check your blood pressure in a variety of situations (at work, for example) may give a clearer picture of your overall blood pressure health.
• It can help detect "white coat" hypertension, an elevation in blood pressure that's brought on by the anxiety of being in the doctor's office.
• It enables those with normal blood pressure to verify their health and be proactive.

Blood pressure is the force of the blood pushing against the walls of the arteries. Each time the heart beats (about 60 to 70 times a minute at rest), it pumps out blood into the arteries. Blood pressure is at its highest when the heart beats (systolic pressure); blood pressure falls when the heart is at rest between beats (diastolic pressure). High blood pressure is a blood pressure reading of 140/90 mmHg or higher. If you have kidney disease or diabetes, the ranges may be different.

Blood pressure ranges

Source: National Heart, Lung and Blood Institute, National Institutes of Health

Getting an accurate reading

If you use an upper-arm model of a blood pressure monitor, you'll get an accurate reading only if the cuff fits properly. A too-small cuff can give falsely high readings; a too-large cuff can give readings that are erroneously low. Although people with very large or very thin arms might not be able to use a regular-sized cuff, many manufacturers offer models with cuffs of different sizes or offer cuffs of various sizes as an optional accessory.

To ensure the best fit, the cuff should fit smoothly and snugly around the upper part of your arm -- you should be able to fit a fingertip under the cuff. The bottom edge of the cuff should be about 1 inch above the elbow crease. To size a cuff, measure your arm's circumference halfway between your shoulder and elbow while standing with your arm hanging at your side: small, 7 to 9 inches (18 to 22 cm); medium, 9 to 13 inches (22 to 32 cm); large, 13 or more inches (32 cm or more).

Arm position is crucial for accurate readings. Sit upright with your arm slightly bent at the elbow. Rest your forearm on a flat surface at the same level as your heart, and extend it straight forward at heart level.

Blood pressure can vary by 30 to 50 mmHg throughout the day, and it can be influenced by diet, activity level, emotions, room temperature, background noise, muscle tension and body position. You'll get the best results if you take measurements at the same time and under the same conditions each day. Early morning and evening readings are usually the most helpful. If work-related stress tends to affect your blood pressure, be sure to take and record measurements on work and nonwork days.

Experts recommend taking at least two readings at intervals of several minutes or longer -- this gives your arm's brachial artery enough time to recover from being squeezed by the cuff -- and recording the average.

Here are more hints to help you get accurate blood pressure readings:

• Avoid exercise, caffeine, alcohol and tobacco for about 30 minutes beforehand.
• Use the bathroom first.
• Rest for about 15 minutes and avoid conversation beforehand.
• Sit comfortably with your back supported, and your legs and ankles uncrossed.
• Remove anything that might interfere with the measurement (jewelry, watch, etc.).

Regardless of what style of blood pressure monitor you use, there's usually a small difference between readings in opposite arms. For best results, use the same arm, wrist or finger every time you measure your blood pressure. According to the Mayo Foundation for Medical Education and Research, the highest reading is typically the truest.

Finally, make sure the monitor you use is accurate. Take it to your doctor's office and compare the readings against those produced by the device he or she uses.

Reviewers say the following about shopping for a home blood pressure monitor.

• Be sure you can read the keys and display comfortably. Some models offer extra-large displays and voice-announced readings.

• If you have an irregular heartbeat, look for a blood pressure monitor that includes circuitry to compensate. Some include alarms to alert users if the unit detects an irregular heartbeat.

• If you plan to travel with your monitor, look for one with a carrying case.

• Take your blood pressure monitor to your healthcare provider when you first buy it and about every six months thereafter to be tested against an office standard. If you drop it or readings suddenly change dramatically, have the unit checked immediately.