New research shows the importance of taking blood pressure in both arms

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  • Guidelines for taking blood pressure indicate that readings should be done for both arms
  • This advice is, however, widely ignored
  • Researchers point out that taking readings from both arms could save lives  

Taking blood pressure has become common practice – whether a patient is being admitted to hospital or just going for a check-up at the doctor – as it allows healthcare professionals to check for hypertension.

Healthcare professionals should consider doing readings for both arms from now on, as a recent study in the journal Hypertension found that a big difference in blood pressure between arms increases death risk.

International guidelines for reading blood pressure do advise that readings should be done from both arms, yet this instruction is still widely ignored. This study was the first to conclude that a large difference in inter-arm blood pressure could increase a patient’s mortality risk. 

Dr Chris Clark, lead author of the study, stated, “Checking one arm then the other with a routinely used blood pressure monitor is cheap and can be carried out in any healthcare setting, without the need for additional or expensive equipment.

"Whilst international guidelines currently recommend that this is done, it only happens around half of the time at best, usually due to time constraints. Our research shows that the little extra time it takes to measure both arms could ultimately save lives.”

Stroke, heart attacks and death 

For the purpose of this study, the researchers “searched for studies recording bilateral blood pressure and outcomes, established agreements with collaborating authors, and created a single international dataset”.

This included inter-arm blood pressure difference data and individual patient data from 24 different studies merged together. From the data collected, the researchers looked at the number of deaths, strokes and heart attacks that occurred over ten years. 

How to read blood pressure

The unit for measuring blood pressure is millimetres of mercury (mmHg) with a reading of two numbers: the systolic (upper maximum) and the diastolic (lower minimum). A high systolic reading indicates hypertension, whereas a big difference in systolic readings between two arms could indicate a narrowing of arteries (often atherosclerosis).

Findings of the study concluded that differences in inter-arm systolic readings increase all-cause mortality, cardiovascular mortality and cardiovascular events.

“We've long known that a difference in blood pressure between the two arms is linked to poorer health outcomes. The large numbers involved in the INTERPRESS-IPD study help us to understand this in more detail.

"It tells us that the higher the difference in blood pressure between arms, the greater the cardiovascular risk, so it really is critical to measure both arms to establish which patients may be at significantly increased risk. Patients who require a blood pressure check should now expect that it's checked in both arms, at least once,” said Dr Clark.

READ | How to accurately measure blood pressure at home

READ | 7 mistakes that can impact your blood pressure reading

READ | This may be why slashing salt lowers blood pressure

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