Blood pressure warning over small change that can have huge impact on readings

Researchers have warned that people may be misdiagnosed with high blood pressure simply because their arm is in the wrong position when a reading is taken.

In the new study, researchers at Johns Hopkins Medicine in the US looked at blood pressure readings when arms were supported on a desk, arms were supported on a lap, and when arms were unsupported and hung at the patient’s side.

Experts found that some arm positions – such as resting the arm on the lap – can substantially overestimate blood pressure readings.

The NHS advises that correct positioning is to sit on an upright chair with a back, placing both feet flat on the floor and resting the arm on a table or desk.

People should also rest for five minutes before taking a reading and then take another reading several minutes later to check it is accurate.

Published in the journal JAMA Internal Medicine, the study found that putting an arm on the lap overestimated systolic pressure (the top number in a blood pressure reading) by 3.9mmHg and diastolic blood pressure — the bottom number – by 4mmHg.

Dr Tammy Brady, from the Johns Hopkins University School of Medicine, said arm position makes a “huge difference” when it comes to an accurate blood pressure measurement and people should always have their arm on firm support such as a desk or table.

Read full story

Source: The Independent, 7 October 2024