Where to Find the Most Accurate Blood Pressure Reading and Avoid 5 Common Mistakes
Research indicates that inaccurate blood pressure readings are widespread, resulting in misdiagnosis and improper management.
Believe your blood pressure reading is correct? Think again. Small errors during routine checks can lead to inaccurate readings and misdiagnosis.
Blood pressure readings are crucial for heart health, yet studies reveal they are often inaccurate. Even a slight mistake can push a reading into the hypertensive range, impacting millions of individuals and potentially resulting in unnecessary treatments and medications. Recognizing common pitfalls and how to avoid them can make a significant difference.
Accuracy in Question
Many trust the rapid blood pressure checks at their doctor’s office. However, a study in the American Journal of Preventive Cardiology in 2021 suggests that this trust may be misplaced. Only 1 in 5 cardiologists, excluding preventive cardiologists, adhere to the recommended guidelines for taking blood pressure despite being confident in their technique. Preventive cardiologists aim to manage heart disease risk factors before they progress.
A position statement from the Lancet Commission on Hypertension Group in 2019 echoed these concerns, revealing that inaccurate blood pressure readings lead to mismanagement in 20–45% of cases in clinical settings. Outdated techniques or limited training often contribute to this. Even a 5-point error can shift a reading into the hypertensive range, potentially affecting up to 84 million individuals worldwide.
Dr. Sean Lucan, a family physician and preventive medicine researcher, is familiar with these issues.
“I recall having my blood pressure checked correctly only once—at my PCP’s office,” he told The Epoch Times. “Perhaps people are in a rush or are inadequately trained. It’s a significant problem.”
Training gaps exacerbate the issue. Blood pressure measurement is typically taught once in medical or nursing school with minimal follow-up. Moreover, many measurements are conducted by medical technicians or support staff who may have less formal training than nurses and doctors.
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“The problem isn’t confined to clinical staff,” Lucan remarked. “It extends to patients using home cuffs without complete, proper education.”
These routine errors can have far-reaching consequences, leading to overdiagnosis and unnecessary medication.
With normal blood pressure at 120/80 mm Hg and hypertension starting at 130/80 mm Hg, even minor errors can push a reading into the hypertensive range. Recognizing common pitfalls and avoiding them is essential to prevent unnecessary treatment and health risks.
Causes of Inaccurate Blood Pressure Readings
1. Wrong Arm Position
A recent study conducted by Johns Hopkins published in JAMA Internal Medicine highlighted how arm position during a blood pressure check can significantly impact the reading, potentially leading to misdiagnosis of hypertension.
Researchers tested three common arm positions—supported at heart level, resting on the lap, and hanging unsupported—with electronic blood pressure readings. They observed significant discrepancies in readings based on arm position.
For example, having the arm rest on the lap could result in systolic and diastolic readings nearly 4 mm Hg higher than the recommended supported-at-heart-level position. An unsupported arm at the side resulted in even greater increases.
Sherry Liu, a study author, emphasized, “Consistently measuring blood pressure with an unsupported arm could lead to an overestimation of BP by 6.5 mmHg, potentially shifting a systolic BP from 123 to 130 or 133 to 140—which is considered stage 2 hypertension.”
2. Wrong Cuff Size
Cuff size is a simple yet often overlooked factor in blood pressure measurement. Cuffs come in different sizes, much like clothing, and must fit the patient’s arm correctly for an accurate reading. A cuff too small can overestimate blood pressure, while one too large can underestimate it.
The American Heart Association recommends using a cuff that wraps around at least 80% of the upper arm. However, studies reveal that incorrect cuff sizes are prevalent, especially for patients with larger or more muscular arms.
A study published in JAMA Internal Medicine in 2023 underscored this issue, showing that using a regular-sized cuff on patients requiring a larger cuff resulted in inflated readings—up to nearly 5 mm Hg with a large cuff and as much as 19.5 mm Hg with an extra-large cuff.
These findings illustrate the hazards of a one-size-fits-all approach to using blood pressure cuffs, particularly for individuals with larger arms. In busy clinical settings, defaulting to a standard cuff can lead to serious errors. The authors stressed the importance of proper cuff sizing to prevent overdiagnosis and unnecessary treatment, advocating for “a renewed emphasis on individualized BP cuff selection.”
3. Crossing the Legs
Although seemingly minor, crossing legs during a blood pressure check can significantly alter the reading. Research published in the Journal of Hypertension revealed that crossing one ankle over the knee raised participants’ systolic blood pressure by an average of 11.4 mm Hg and diastolic pressure by 3.8 mm Hg compared to readings with feet flat on the floor.
This leg position affects blood pressure by increasing cardiac output, leading to a rise in arterial pressure due to the increased blood flow. However, since peripheral resistance does not adjust to counteract this rise, overall blood pressure spikes. Interestingly, crossing legs at the ankles does not produce the same effect on readings.
Study authors suggest that patients keep their feet flat on the floor during measurements to avoid artificially elevated readings, highlighting that “leg position should be addressed in all guidelines and publications regarding BP.”
4. Full Bladder
Having a full bladder not only causes discomfort but can also elevate blood pressure. Researchers found that middle-aged women with a full bladder exhibited an average increase of 4.2 mm Hg in systolic blood pressure and 2.8 mm Hg in diastolic pressure compared to measurements taken after relieving themselves.
Although most pronounced after three hours, the increase did not escalate with longer durations. This suggests that while a full bladder can temporarily heighten blood pressure, the discomfort and tension—rather than time—are the primary contributors.
For individuals who have delayed a restroom visit for too long, this spike in blood pressure is a natural response to bladder distension. A quick trip to the restroom before a blood pressure check can prevent artificially elevated readings.
5. White Coat Hypertension
For up to a third of patients, a visit to the doctor’s office alone can trigger spikes in blood pressure readings, known as white coat hypertension. This temporary increase, often induced by anxiety, can raise systolic readings by as much as 10–20 mm Hg.
Dr. Evan Levine, a cardiologist at Mt. Sinai Health System, addresses white coat hypertension by allowing patients time to relax and repeating measurements. Studies support this approach, showing that introducing a gap between readings can mitigate anxiety-induced spikes. Levine often conducts a second reading post-exam, enabling patients to calm down and ensuring more accurate results.
Why Accuracy Matters
Lucan states, “Inaccurate blood pressure readings undoubtedly contribute to patients being over-diagnosed, over-medicated, and exposed to the risks associated with both.”
Incorrect blood pressure readings can set off a chain of unnecessary treatments and stress. Misdiagnosed hypertension may lead to the initiation of lifelong blood pressure medications, such as ACE inhibitors or beta-blockers, which come with potential side effects like dizziness, fatigue, and kidney problems. For individuals without true hypertension, these side effects are unnecessary burdens.
This issue has garnered the attention of national organizations, including the American Heart Association and the American Medical Association, who have launched the Target: BP initiative to enhance blood pressure management nationwide.
An essential component of this program is retraining healthcare providers in accurate measurement techniques every 6–12 months ideally. Studies reveal that even a 30-minute online module can enhance provider skills and confidence. The program also emphasizes self-monitoring outside of healthcare settings as a vital method for accurate diagnosis.
Lucan proposes a uniform national approach to blood pressure education. “I firmly believe there should be a unified educational campaign. Perhaps call it ‘Check Right,'” he suggests.
Clear, consistent guidelines can reduce misdiagnoses, improve treatments, and create a healthier, more empowered patient community, according to Lucan.
There’s No Place Like Home
Experts increasingly recommend that patients monitor their blood pressure at home rather than solely relying on clinic readings. Dr. Jackson Wright, director of the Clinical Hypertension Program at University Hospitals, states that home blood pressure monitoring (HBPM) has become the preferred method for managing hypertension.
Home monitoring emerged as a necessity during the pandemic as patients turned to remote care. Today, health organizations, including the American Heart Association, widely endorse it. HBPM offers a comprehensive view of blood pressure trends, giving patients and doctors a more accurate basis for making treatment decisions than a single clinic reading.
A study in the Journal of the American College of Cardiology in 2021 found that one week of home blood pressure monitoring was more reliable and closely associated with heart health indicators than clinic measurements.
HBPM enables patients to exercise greater control over their health. Studies indicate that regular home monitoring, particularly when paired with telehealth support from nurses, pharmacists, or community health workers, enhances blood pressure management and increases patient engagement in their care.
As mentioned by cardiologist Dr. Evan Levine, “When it comes to BP measurements, there’s no place like home.”
Getting It Right
A single high blood pressure reading does not equate to hypertension automatically.
Guidelines recommend taking at least two readings during a single visit to ensure accuracy. Doctors typically repeat the test at a follow-up visit to diagnose hypertension accurately. This two-step process helps rule out temporary spikes caused by stress or simple errors, providing a more reliable understanding of a patient’s actual blood pressure.
While manual blood pressure checks were previously considered the gold standard, most readings today are conducted using automatic cuffs. A meta-analysis from 2019 found that automated in-office measurements are more precise than manual readings, closely aligning with ambulatory monitoring, the best predictor of cardiovascular risk.
For both patients and healthcare providers, a few simple steps can ensure blood pressure readings are as accurate as possible. Lucan recommends emphasizing the basics for reliable measurements, whether in a clinical setting or at home:
- Use the Restroom: Address any urgency before taking your blood pressure to alleviate temporary high readings.
- Avoid Stimulants: Steer clear of caffeine, nicotine, or exercise for at least 30 minutes before, as these can temporarily raise blood pressure.
- Stay Calm: Take deep breaths and relax. Refrain from speaking during the measurement. If white coat hypertension is a concern, consider monitoring blood pressure at home.
- Positioning: Sit upright with your back supported, feet flat on the floor, and your arm supported at heart level.
- Use the Right Cuff Size: Ensure the cuff encircles at least 80% of the upper arm for accurate results.
- Place the Cuff on Bare Skin: Avoid placing the cuff over clothing for an accurate reading.
- Repeat Readings: If the initial reading is high, wait a few minutes before taking another to ensure accuracy.
