Accurate blood pressure (BP) measurements are vital for diagnosing and managing cardiovascular health, yet many people might be unaware that small factors, like arm position, can skew results.
In a status posted on X by Dr Sudhir Kumar, he pointed to how non-standard arm positioning can lead to significant overestimation of blood pressure readings, which may result in unnecessary concerns or incorrect treatment adjustments.
He wrote that non-standard arm positions during blood pressure (BP) measurements can lead to overestimation of BP readings. “Guidelines for blood pressure (BP) measurement recommend arm support on a desk with the midcuff positioned at heart level.” However, in clinical practice, non-standard positions, such as resting the arm on the lap or leaving it unsupported at the side, are often used.
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Incorrect measurements can lead to falsely elevated BP readings (Source: Freepik)
Dr Sudhir added that a recent study found that these non-standard arm positions can significantly overestimate BP readings. Specifically, when the arm was supported on the lap, systolic BP was overestimated by 3.9 mm Hg and diastolic BP by 4.0 mm Hg. An unsupported arm at the side led to an overestimation of systolic BP by 6.5 mm Hg and diastolic BP by 4.4 mm Hg.
Despite established guidelines, improper arm placement during BP measurement remains a common practice in both clinical and home settings. Understanding why these seemingly minor deviations have such an impact on BP results is crucial, especially as hypertension continues to be a growing health concern globally.
Physiological mechanisms that cause blood pressure to be overestimated
Dr Prateek Chaudhary, senior consultant, Interventional Cardiology at Asian hospital, says, “The position of your arm, where the BP cuff is tied and inflated, plays a significant role in obtaining an accurate reading. If your arm is above the level of your heart, which is typically the middle of the sternum, your BP may read lower than it actually is. On the other hand, if your arm is positioned below heart level, your BP may read higher than it should.”
This discrepancy occurs due to the effect of gravity, he adds. When your arm is lifted above heart level, the gravitational pull affects the blood pressure reading, causing it to appear lower than it really is. Conversely, if your arm is below heart level, the reading can be higher.
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Best practices for ensuring a correct arm position when taking BP
To ensure a correct BP reading, Dr Chaudhary recommends the following steps:
- Be seated for at least five minutes before taking your blood pressure.
- Avoid caffeine, tea, or tobacco at least 30 minutes before the measurement.
- Sit with your back supported, feet flat on the ground, and legs uncrossed.
- Ensure your arm is supported, with the BP cuff positioned at heart level (aligned with the middle of the sternum).
- The BP cuff should encircle 75% to 100% of your arm. Different cuff sizes are needed for lean or larger patients, so ensure the cuff size is appropriate.
- BP is usually measured in both arms, and the higher reading is taken as your blood pressure.
- If taking repeated measurements, there should be a gap of at least one to two minutes between them.
Dr Chaudhary adds that the BP cuff should fit snugly around your arm. You should be able to insert one or two fingers between the cuff and your arm, but it should still be tight enough to provide an accurate reading.
Can repeated improper BP measurements lead to misdiagnosis or over-prescription of medications
Dr Chaudhary emphasises that incorrect measurements can lead to falsely elevated BP readings, resulting in a misdiagnosis of hypertension. “If the BP reading is lower due to improper measurement, the disease may be missed, delaying necessary treatments or lifestyle changes, which could negatively affect your health.”
Patients can avoid these issues by adhering to the guidelines mentioned or by visiting a medical practitioner who is properly trained in BP measurement. Following these precautions will help ensure accurate BP readings and avoid unnecessary complications.
📢Non-standard Arm Positions during BP Measurements can Overestimate BP
✅Guidelines for blood pressure (BP) measurement recommend arm support on a desk with the midcuff positioned at heart level.
➡️Still, nonstandard positions are used in clinical practice (eg, with arm… pic.twitter.com/AIWFGslvc1— Dr Sudhir Kumar MD DM (@hyderabaddoctor) October 9, 2024
DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.
