Standardization needed in use of home blood-pressure monitoring
By LJ Anderson
Millions of American homes have a blood pressure monitor, and the use of home blood-pressure monitoring is easier, cheaper, and potentially more reliable than measurements taken in a medical office. However, the device may not have been checked for accuracy, may not be a recommended device, and its owner may be unaware of how best to use it.
An estimated 60 million Americans are hypertensive, having a systolic pressure of 140 mm Hg or higher, and a diastolic pressure of 90 mm Hg or higher. High blood pressure or hypertension puts them at greater risk for heart disease, stroke and kidney disease. A Gallup study (2006) found that almost 65 percent of Americans with hypertension own a home blood pressure monitor.
Nancy Houston Miller, RN, BSN, is associate director of the Stanford Cardiac Rehabilitation Program. She was the second author of a 2008 report titled Call to Action on Use and Reimbursement for Home Blood Pressure Monitoring, and she is involved in efforts to encourage greater standardization in the use of home blood-pressure monitoring.
When patients start on home blood-pressure monitoring, they should bring their devices in and compare them
Millions of American homes have a blood pressure monitor, and the use of home blood-pressure monitoring is easier, cheaper, and potentially more reliable than measurements taken in a medical office. However, the device may not have been checked for accuracy, may not be a recommended device, and its owner may be unaware of how best to use it.
An estimated 60 million Americans are hypertensive, having a systolic pressure of 140 mm Hg or higher, and a diastolic pressure of 90 mm Hg or higher. High blood pressure or hypertension puts them at greater risk for heart disease, stroke and kidney disease. A Gallup study (2006) found that almost 65 percent of Americans with hypertension own a home blood pressure monitor.
Nancy Houston Miller, RN, BSN, is associate director of the Stanford Cardiac Rehabilitation Program. She was the second author of a 2008 report titled Call to Action on Use and Reimbursement for Home Blood Pressure Monitoring, and she is involved in efforts to encourage greater standardization in the use of home blood-pressure monitoring.
Q: How reliable are home blood-pressure measurement devices?
A: The American Association for Medical Instrumentation (AAMI) certifies blood pressure devices for home use, and the companies have to go through rigorous reliability and validity testing. There are a lot of devices that have never passed those standards, so we recommend that patients use AAMI or the British Hypertension Society (www.bhsoc.org) to find out about certified devices.
When patients start on home blood-pressure monitoring, they should bring their devices in and compare them against their doctor’s device. A person’s blood pressure is often 5 mm lower both in systolic and diastolic (pressure) when measured at home as opposed to an office setting. White-coat hypertension — an increase in blood pressure due to being in a medical environment — is common in about 20 percent of the population, and needs to be considered. And the best way to determine that, or whether the patient actually has sustained hypertension, is by a home blood pressure device. If blood pressure is continually elevated above 135/85 at home, ambulatory blood-pressure monitoring can be done over a 20-hour period. You put the device on and get blood pressure readings every 15 to 30 minutes, to see what is going on during the day and night.
Q: What has replaced the mercury manometer for blood pressure measurement?
A: The devices used primarily in hospitals are automated oscillometric devices that don’t have mercury. There are still centers that use mercury manometers because they provide the most definitive measurements, but they have mostly been replaced with automatic devices (due to environmental concerns about mercury). I’m in a cardiac rehab clinic where we have automatic devices, but we’re lucky to still have mercury devices on standing IV poles — and we’re very careful with them. There has been some debate about the use of automatic devices if they aren’t calibrated, and accuracy with different heart rhythms may be a potential problem with their use.
The automatic devices (in clinics and hospitals) are different from home automated devices. My feeling is that home blood-pressure devices should become the gold standard for measuring blood pressure as you can obtain many more readings during daily life. However, we haven’t achieved a policy yet where there is insurance coverage for people to buy them or reimbursement for health-care providers to review blood pressure records and counsel about the use of blood-pressure monitors. We have to develop standards (in a way) similar to how the American Diabetes Association believed that home blood-glucose monitoring was critically important for diabetic patients, encouraged passage of pertinent legislation, and it was written into law.
Q: What factors are important in taking an accurate blood pressure measurement?
A: There’s a need for standardization (of taking blood pressure) in home and office settings, in patient educational materials and training materials for health care professionals, and insuring that people are trained and retrained on technique — such as using appropriate cuff size and being in a seated position, resting, for at least two minutes. Also, because devices are in so many settings, that’s a difficult problem. The question will remain if it is good enough to simply bring a device in and check for its accuracy in an office. We have to work on several fronts to ensure that device companies meet AAMI standards, patients purchase appropriate devices, health-care professionals are reimbursed for checking patient devices against office devices, and that appropriate technique is used. It is by no means an easy problem to solve.
Q: How does one know when a measurement device is reliable?
A: You have to check it against an office device, and see if the (comparative) measure is within 5 mm. The best thing, though, is to take a series of measures to check for accuracy. Our recommendation in the Call to Action report is to monitor blood pressure for seven days at home, twice daily. You discard the first day’s measurement, and then measure twice a day, and average those readings. The reason why we think this is the gold standard is that you get many more measures than in a single office visit every three to four months. Observing morning and evening readings really enables you to see if blood pressure is controlled.
She can be reached at lj.anderson@yahoo.com or www.ljanderson.com.
Tags: diabetic patients, environmental concerns, home blood-pressure, Stanford Cardiac Rehabilitation Program, White-coat hypertension
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