Wrong Arm Position = Wrong Measurement Of Blood Pressure

This is especially important to know if you measure your own blood pressure at home.

Even if you don’t, it’s still good to know this as healthcare providers also can (and often will) do it wrong, especially if they are under time pressure (e.g. they need to get you out of their office and the next person in):

From the heart

Many things can change our blood pressure, and even gravity changes (considerably!) our blood pressure locally.

For example, even with good circulation, so long as we are in the Earth’s gravity under normal conditions (e.g. not skydiving, not riding a rollercoaster, etc), our blood pressure will always be higher below our heart, and lower above it, because gravity is pulling our blood downwards; this is also why if your circulation is not good, you may feel light-headed upon sitting up or standing up, as the bloodstream takes a moment to win a battle against gravity. This is also why blood rushes to your head if you are hanging upside down—increasing the local blood pressure in your head, which unlike your feet, isn’t used to it, so you feel it, and the effect may be visible from the outside, too.

When it comes to having your arm above or below your heart, the difference is less pronounced as it’s only a small change, but that small change can make a big difference:

• If the cuff is above heart level → Lower blood pressure reading.
• If the cuff is below heart level → Higher blood pressure reading.
• Every 1-inch difference causes a 2 mmHg change in readings.

For the reading to be accurate, the blood pressure cuff therefore needs to be at the same height as your heart.

You may be thinking: “my heart is bigger than an inch; do I aim for the middle?”

And the answer is: ideally the cuff should be at the same height as the right atrium of the heart, which is under the midpoint of the sternum.

However, your arm needs to be supported at that height, because if you have to keep it there using your own power, that will mean a tensing of your muscles, and increase in both heart rate and blood pressure. In fact, studies cited in the video found:

• Unsupported arm, in healthy patients → Systolic +8 mmHg, Diastolic +7 mmHg.
• Unsupported arm, in high blood pressure patients → Systolic +23 mmHg, Diastolic +10 mmHg.

Some other considerations; firstly, correct sitting posture:

• Sit upright with back support
• Feet flat on the floor, legs uncrossed
• Arm should be outward from the body and, as per the above explanation, supported (armrest, table, etc.)

And finally, you should be relaxed and at rest.

For example, your writer here is due for a regular checkup in a couple of weeks, and usually when I go there, I will have walked a couple of miles to get there, then bounced cheerfully up 6 flights of stairs. However, for this appointment, I will need to make sure to arrive early, so that I have time for my (so far as I know, happy and healthy) heart to return to its resting pulse and blood pressure.

Also, if you are anything like this writer, the blood pressure cuff activating is not a relaxing experience (and so invites a higher pulse and blood pressure), so it’s better to take three readings and then discard the first one, and record the average of the second two (I do it this way at home).

Similarly, if a medical environment in general is stressful for you, then taking two minutes to do a little mindfulness meditation, or even just breathing exercises, can be good.

For more on all of these, plus also comments on issues such as correct cuff size and tightness, enjoy:

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Want to learn more?

You might also like to read:

Common Hospital Blood Pressure Mistake (Don’t Let This Happen To You Or A Loved One)

Take care!