Saturday, April 13, 2024

It’s often best to take blood pressure at home – The Washington Post

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High blood pressure (or hypertension) is a leading risk factor for some of the most common and deadly medical emergencies, including heart attacks and strokes. Constantly high pressure can damage the tissues inside your arteries, leading to plaque buildup and reducing blood flow to your heart and brain.

But measuring your blood pressure accurately can be tricky. In fact, when you have it taken in a doctor’s office, there’s a good chance those numbers won’t reflect your actual blood pressure on a regular day. Raj Padwal, a professor of medicine at the University of Alberta in Canada who runs a hypertension clinic, says he doesn’t usually order blood pressure measurements in clinic for his patients “because 50 percent of time, they are inaccurate. .”

There are several reasons why measurements taken in a doctor’s office can be misleading. But the good news is that there is a simple and relatively inexpensive way to get an accurate picture of your blood pressure from the comfort of your own home.

The problem with blood pressure checks at the doctor’s office

Blood pressure is extremely sensitive and changes from moment to moment. This is “affected by emotional state, mental health, physical activity, ambient temperature, medications, whether you ate, whether you slept well, and so on,” says Padwal.

This vital sign is measured with two numbers: systolic pressure, the top number, which represents the pressure on your arteries when your heart contracts; and diastolic pressure, the bottom number, representing the pressure on your arteries when your heart is at rest.

Getting an accurate blood pressure reading requires following a very specific procedure that involves keeping your feet flat on the floor, your back against a sturdy chair, and your arm on a flat surface. Additionally, the cuff should be at the level of your heart and placed directly on your skin (not on your shirt) and you should empty your bladder and sit quietly for several minutes before taking the reading. But many of these requirements are not routinely met in a doctor’s office, where staff may be too eager to get you into the correct position.

Additionally, medical practices can have equipment issues. You might assume that blood pressure monitors are more accurate than home monitors, but that’s often not the case. Analog devices that use a cuff and pressure gauge need to be calibrated every few months, but that rarely happens, says Jordana Cohen, an associate professor of medicine and epidemiology at the Perelman School of Medicine at the University of Pennsylvania. Digital blood pressure monitors, also used in medical settings, are more reliable. But only a fraction of them have been independently checked for accuracy, a process called validation. Additionally, your doctor’s office may not have the right cuff size for your arm, and a cuff that is too large or too small can result in an inaccurate reading.

Some people also suffer from what is called white coat hypertension, where their blood pressure rises in a doctor’s office, likely due to the stress of a doctor’s visit. Others have masked hypertension, in which their blood pressure drops to a lower level in a doctor’s office, perhaps because those who are very stressed in their daily lives feel calmer in a doctor’s office. The true prevalence of these conditions is unclear, but it is estimated that 15% to 30% of people have white coat hypertension, and about 32% of those with normal office blood pressure measurements have white coat hypertension. masked hypertension.

All of this may explain why your blood pressure readings from a doctor can vary so much. A 2023 study that evaluated data from more than half a million people found that between two consecutive visits to the doctor, a person’s systolic blood pressure changed by an average of 12 mmHg (the unit of blood pressure measurement) in both directions.

This isn’t just a small rounding error. When you start taking a new blood pressure medication, doctors generally expect it to lower your blood pressure by less than 12 mmHg, says one of the study’s authors, Harlan Krumholz, a cardiologist and professor of medicine at the Yale School of Medicine. This means that if your doctor relies solely on in-office measurements, he or she cannot be sure whether a drop in your blood pressure is due to the action of the medication or something else.

Krumholz says the only way to overcome this problem is to collect a large number of measurements – around 20 – and average them. Fortunately, experts say, there’s a simple way to alleviate all of these problems: home blood pressure monitoring.

Why home blood pressure monitoring works so well

When measuring at home, you can purchase a high-quality monitor with a cuff that fits your arm. You can also be sure to prepare properly and use the correct procedures when seated. And you can take multiple measurements on different days and provide this data to your doctor.

Monitoring blood pressure at home is especially useful for anyone whose office readings indicate high blood pressure and for those at high risk of heart disease due to preexisting health conditions like diabetes, Padwal says. It can also be useful for monitoring the effect of a new medication or adjusted dosage, or for people who are pregnant or postpartum and need to be on the lookout for a serious form of high blood pressure called preeclampsia.

And not only can home monitoring be more accurate than in-office checks, but some studies have shown that it can actually help you control your blood pressure, especially in the first few months of using a blood pressure monitor.

Choosing a blood pressure monitor

Purchasing an accurate home blood pressure monitor is essential. Although most manufacturers have not published the results of any accuracy tests, some medical groups have compiled lists of devices validated by independent experts. Every expert we spoke with recommended the American Medical Association’s list of validated blood pressure devices as a good place to start when shopping for a home monitor. Consumer Reports also rates BP monitors (although the ratings are behind a paywall).

Home blood pressure monitors come in two main varieties: those that sit on your upper arm and those that sit on your wrist. In general, experts (and CR) recommend arm monitors, which tend to be more accurate because there is less room for error in their positioning.

But using the correct cuff size is crucial to getting accurate readings, and some people with larger arm circumferences may not be able to find an arm monitor with a suitable cuff size. In these cases, wrist monitors can be a good alternative. You just need to be very careful to position them correctly. None of the wrist monitors in CR’s testing scored high enough to earn our recommendation, but several still achieved very good accuracy scores.

You may be wondering if an alternative to purchasing your own blood pressure monitor is to use a blood pressure kiosk at your pharmacy. But Padwal says very few public blood pressure kiosks have been validated by independent experts. Additionally, it can be difficult to properly follow directions for taking blood pressure correctly when you’re in the middle of a busy pharmacy.

Copyright 2024, Consumer Reports Inc.

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