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Blood Pressure: Wrong Arm Position Distorts Results, Here's the Right Technique

Having your arm in the wrong position during blood pressure measurements can lead to "significantly higher" readings than when your arm is in the ideal position, a new study suggests. And mistakes are common.

 

Are you in the right position when you measure your blood pressure or when your doctor takes it? According to a study published in the journal JAMA Internal Medicine, a small variation in posture can lead to an overestimation of blood pressure. Discover THE right position to control your blood pressure.

 

Three "classic" positions studied


Researchers at Johns Hopkins University recruited 133 adults aged 18 to 80 between August 2022 and June 2023. All were randomly assigned to have their blood pressure measured while their arm was positioned in three different ways: resting on a desk, as is standard recommended practice; resting on their knees; or hanging at their side, unsupported.


Each participant underwent a total of 12 blood pressure measurements with their arm in each of these positions. And the measurements were not much alike:


  • When their arm was supported on a desk as recommended by standard clinical guidelines, their average blood pressure was 126/74.

  • When participants' arms rested on their knees during measurement, the mean blood pressure was 130/78, (an overestimation of systolic blood pressure of 3.9 mm Hg and an overestimation of diastolic blood pressure of 4 mm Hg).

  • When their arms were hanging at their sides, the average of their measurements was 133/78 (an overestimation of systolic blood pressure of 6.5 mm Hg and an overestimation of diastolic blood pressure of 4.4 mm Hg).


Wrong diagnosis possible even at the doctor


The correct position would therefore be to place the arm correctly supported on a table, with the middle of the cuff positioned at heart level. This is not always the one adopted and it is a mistake.


According to the findings, failing to consistently position and support your arm properly during a measurement could lead to a misdiagnosis of high blood pressure , which some experts say could eventually lead to unnecessary treatment.

“Health care providers need to be reminded of the importance of taking the time to do these steps correctly,” said the study’s lead author, Dr. Tammy Brady. “I also hope this study will educate patients and allow them to advocate for appropriate measurement when they’re in a clinical setting. But also, I hope it will teach them how to position their arms properly, because our findings also apply to home measurements.”


How to Check Your Blood Pressure Accurately


While arm position can affect blood pressure measurement, the entire procedure may also need to be revised for accurate results. According to the authors, several tips should also be followed:


  • Wear an armband that is the correct size and snug against your arm (otherwise the measurement may be inaccurate).

  • Have your back supported.

  • Keep your feet flat on the floor with your legs uncrossed.

  • Have your arm in a proper position: the cuff should be positioned at heart level with your arm supported on a desk or table.


"In the 30 minutes before taking your blood pressure, avoid smoking, exercising, consuming caffeine, alcohol and... arguing. Don't be psychologically stressed

 ," adds Dr. Gail Adler, cardiovascular endocrinologist, to CNN.


Experts advise to sit on a chair, get into the right position and for five minutes, relax, do not talk, rest your arm comfortably, sit with your back straight, keep your legs uncrossed and your feet flat on the floor. Make sure you do not have the urge to urinate, because if you have the urge to urinate, it will increase your blood pressure.

 

As a reminder, blood pressure is considered normal when it is less than 140/90 mmHg in the doctor's office. When BP is taken by self-measurement or by ABPM, it is considered normal when it is less than 135/85 mmHg.

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