How to get the most accurate blood pressure reading
Blood-pressure readings may seem arcane at first glance, but you don’t need medical training to make sense of them. Simply put, the first number, known as the systolic pressure, represents how much force is on your veins when your heart pumps. The second number, the diastolic pressure, shows how much force remains in between heartbeats.
As these numbers rise, so does your risk of cardiovascular events. The Public Health Agency of Canada considers values of less than 120/80 in adults to be “optimal” and 120 to 129/80 to 84 to be “normal.” (There’s no lower healthy limit so long as you feel well, but see a doctor if you’re chronically dizzy or light-headed.) “High-normal,” 130 to 139/85 to 89, is the range where it may be worth changing your lifestyle (these foods can lower blood pressure), though your cardiovascular risk probably isn’t great enough to justify medication.
Values of 140/90 and higher are considered “hypertension,” a situation where lifestyle interventions are highly recommended and taking drugs is usually worth the risk. For home readings, however, the threshold is 135/85: you tend to be more relaxed in the comfort of your own space than at the doctor’s office.
Your blood pressure fluctuates throughout the day due to factors such as stress levels, caffeine intake and physical activity. Therefore, doctors won’t usually diagnose hypertension after just one test. Instead, they might ask you to use a home-monitoring device or come back another day to see if your results are still the same.
Before a blood-pressure test, sit down for five minutes in a quiet environment, if possible, advises Dr. Joep Perk, a European Society of Cardiology spokesperson for hypertension and prevention. During the test itself, breathe normally, support your elbow at heart level and don’t talk. Make sure the arm cuff is in contact with your skin, not your clothing.
If your blood pressure has never been high, you only need to check it once every few years. People who are hypertensive, however, are encouraged to record measurements regularly—perhaps once or twice a week. “This gives doctors the data they need to tailor your medication,” says Perk.
As a bonus, frequent blood-pressure checks remind you to follow your prescription, since you’ll likely see the numbers rise if you don’t. “Hypertension doesn’t make you feel physically unwell,” Perk says, “and it can be hard to feel motivated to adhere to treatment. Self-monitoring helps you take an active interest in good control.”
Next check out these surprising factors you didn’t know were affecting your blood pressure.