Can blood pressure monitors be wrong, or give false readings? Yes, and we've seen a wide variance of accuracy in testing home blood pressure monitors when measured against our hospital-grade reference monitor.
Check for accuracy
“If the systolic blood pressure (the top number) on your cuff is within 10 points of the monitor, then it's generally accurate,” he says. Most home blood pressure machines last for about two or three years. After that, check it at your doctor's office annually to make sure it's still accurate.
Get to the Heart of the Study Results
Dozens of at home blood pressure machines were tested in the study. According to the results, the participants' home blood pressure monitor readings were off by around 5 mmHg a shocking 70% of the time.
Of the 278 upper-arm cuff devices included in the new study, which was published in April 2020 in the journal Hypertension, less than 20 percent had been validated, meaning the cuffs had not been proved to give accurate readings according to internationally accepted standards.
A digital blood pressure monitor will not be as accurate if your body is moving when you are using it. Also, an irregular heart rate will make the reading less accurate. However, digital monitors are the best choice for most people.
Blood Pressure Cuff Placement
If the cuff is too small, it can add 2 to 10 points to your bp measurement. Be sure to roll up your sleeve for a blood pressure test and also let your doctor know if the cuff feels too tight around your arm.
Inaccurate blood pressure measurement could lead to incorrect diagnosis and inappropriate treatment. The chance to reduce the risk of heart attack or stroke could also be missed. Over 3000 blood pressure monitors are available but less than 15% of these have been properly tested for accuracy.
You could have white coat hypertension. This condition occurs when blood pressure readings at a health care provider's office are higher than they are in other settings, such as at home. It's called white coat hypertension because people who measure blood pressure sometimes wear white coats.
Blood pressure has a daily pattern. Usually, blood pressure starts to rise a few hours before a person wakes up. It continues to rise during the day, peaking in midday. Blood pressure typically drops in the late afternoon and evening.
Everyone's blood pressure rises and falls many times during the course of a single day, sometimes even within minutes. Many factors contribute to these changes, including physical activity, emotion, body position, diet (especially salt and alcohol intake), and sleep deprivation.
Men, older people, and those with larger arm circumferences were more likely to get inaccurate results, and devices with hard cuffs were more likely to produce them. These factors can give you a skewed reading because a poor fit can alter pulse pressure or make your veins stiffer, the researchers explain.
Your first blood pressure reading will almost always be higher than the second due to a wide range of factors, both environmental and psychological. These factors include white coat syndrome, stress, and having a full bladder.
Acute meal ingestion, caffeine or nicotine use can all affect BP readings, leading to errors in measurement accuracy. If the patient has a full bladder, that can lead to an error in systolic BP of up to 33 mm Hg, and the white-coat effect can have an error of up to 26 mm Hg.
At the beginning, measure your blood pressure at least twice daily. Take it first in the morning before eating or taking any medications. Take it again in the evening. Each time you measure, take two or three readings to make sure your results are the same.
Anxiety doesn't cause long-term high blood pressure (hypertension). But episodes of anxiety can cause dramatic, temporary spikes in blood pressure.
Readings are accurate within 2-4 mm of Hg when measured using the sphygmomanometer.
Practice stress relief
For example, breathe deeply and exhale slowly. Try a few of these breaths before your blood pressure reading. Reciting a poem or verse in your mind may help you relax, too.
Something as simple as keeping yourself hydrated by drinking six to eight glasses of water every day improves blood pressure. Water makes up 73% of the human heart,¹ so no other liquid is better at controlling blood pressure.
The device should measure blood pressure on the upper arm, which produce a more reliable result than those that measure from the wrist.
Automated office blood pressure readings are more accurate than typical office readings among patients with hypertension, according to a JAMA Internal Medicine meta-analysis.
While both numbers in a blood pressure reading are essential for diagnosing and treating high blood pressure, doctors primarily focus on the top number, also known as systolic pressure.
Arm position
Dependency of the arm below heart level leads to an overestimation of systolic and diastolic pressures and raising the arm above heart level leads to underestimation. The magnitude of this error can be as great as 10 mm Hg for systolic and diastolic pressures.
It is recommended to wait at least 1 minute between blood pressure (BP) readings.
Blood pressure rises progressively during breath-holding, even width pre-oxygenation and hypocapnia. Using the clinically used technique of deep inspiratory breath-holds with air, Figures 1 and 2 show that blood pressure rose progressively in all subjects during breath-holding.