How To Take an Accurate Blood Pressure Reading

Did you know that approximately 4.6 million Canadians aged 20 years and older (19% of the population) have high blood pressure? That is why it is so important that we get our blood pressure checked and do our best to make it accurate.

The first part of accuracy is to choose the appropriate blood pressure cuff size. Cuffs that are too short or too narrow may give a falsely high reading. Using a regular sized cuff on a large arm may lead to a false diagnoses of hypertension. This means that heavy or very muscular people with thick arms need a larger bladder, while children need a smaller bladder.

* Ask your doctor to make sure they are using the appropriate cuff for your arm.

– The width of the inflatable bladder should be about 40% of the upper arm circumference (about 12-24 cm in the average adult).
– The length of the inflatable bladder should be about 80% of upper arm circumference (almost long enough to encircle the arm).

Here are some things that you should do before taking your blood pressure:

-You should not smoke, drink caffeinated beverages, or exercise 30 minutes before your blood pressure is measured.

-The room should be quite and comfortably warm

-Your arm when taking the blood pressure should be at mid chest level, or your elbow at the level of your heart

-Remove excess clothing that might interfere with the BP cuff or constrict blood flow in the arm.

-Your legs should not be dangling or crossed over. It’s better if you rest for 5 minutes in that position before the measurement.

-Try not to talk during the measurement.

– When the doctor is deflating the cuff. It is recommended that the pressure should fall at 2 – 3 mmHg per second, anything faster may likely result in an inaccurate measurement. This means when the doctor is letting the pressure come out of the cuff that it should take at least 10 seconds.

-If you need to check the pressure again for accuracy wait about five minutes between readings. Typically, blood pressure is higher in the mornings and lower in the evenings.

-If the blood pressure reading is a concern, masked or white coat hypertension is suspected, a 24- hour blood pressure study may be required to assess your overall blood pressure profile.

Below is a table for blood pressure measurements (Canadian Guidelines):

Category (Systolic / Diastolic)
Normal            (120-129 / 80-84)
High – Normal (130-139 / 85-89)
High blood pressure (measured in a doctor’s office) (140 / 90)
High blood pressure (measured at home with home monitoring device) (135 / 85)
High blood pressure for people with diabetes (140 / 90)

* One high reading does not necessarily mean you have high blood pressure. If you have one high reading, you should have it measured at least two more times on separate days to check whether it is consistently high.

To summarize the table above:

Normal blood pressure is between 120/80 mm Hg and 129/84 mm Hg.

Blood pressure that is consistently more than 140/90 mm Hg when measured in the doctor’s office or 135/85 mmHg when measured at home is considered high. If you have diabetes, 140/90 mm Hg is high.

* If your blood pressure is between 130/85 mm Hg and 139/89 mm Hg, you have “high-normal” blood pressure, which is more likely to develop into high blood pressure.

Because hypertension is a “silent disease” many people are not worried about it. However hypertension can cause much harm to the body if untreated, some of the harms it can cause include the following: stroke, vascular dementia, hypertensive retinopathy, left ventricular dysfunction, angina, heart attack, heart failure, chronic kidney disease and intermittent claudication.

The good news is that you can try lifestyle changes to make it better. One of the best treatments is to loose weight, you can also try a DASH diet (dietary strategies against hypertension – talk to your doctor about this). It is also important to have low sodium intake, increase your physical activity (discuss with your doctor), use alcohol in moderation, stress management and please (pretty please) stop smoking.

If the lifestyle management is not working to control your blood pressure (follow up should be in about 3 – 6 months) you may have to talk with you doctor about trying some medications to get your blood pressure under control.

“Take care of your body. It’s the only place you have to live”.

Love my life and your life,
Peter Eppinga M.D.