Measuring Blood Pressure

Measuring Blood Pressure

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You don’t always have to go to your doctor’s office to have your blood pressure checked. You may be able to do it at your pharmacist. Or you can monitor your own blood pressure at home. In fact, measuring blood pressure at home may give you a more accurate reading, because often at the doctor’s surgery, nervousness or anxiety can raise your blood pressure and the reading may be higher than normal.

There are various devices on the market that will allow you to do measure your own blood pressures. Accurate and easy to use, they are available from a pharmacist or a medical products supplier. 

How does it work?

Though the devices look different, each works in a similar way. The machine is connected to an inflatable pressure bag that you wrap around your upper arm. A pump in the device pumps up the bag with air until the circulation of your arm’s main artery is blocked. Then the pressure in the bag slowly drops slowly and as it drops, blood starts flowing again through the artery. The machine measures the pressure in the bag and takes the pressure at two important points: 

  • The pressure at which the heart can force pump through the inflated bag, which is the greatest pressure in the arteries as the heart pumps blood through the arteries— this is the systolic pressure and is usually around 120mm Hg (or somewhere between 110 and 130mmHg).
  • The lowest pressure in the arteries, as the heart relaxes and momentarily stops pumping til the next heart beat. This is called the diastolic pressure. It is usually around 80mm Hg (somewhere between 70 and 80mmHg).

What is normal?

For most people, a healthy blood pressure measurement is 120/80 mm Hg, referred to as 120 over 80. If it is consistently abnormally high at rest, then you have hypertension. A blood pressure of 140/90 at rest is normally considered to be hypertension. 

However, your blood pressure normally fluctuates somewhat; for example, it is higher when you exert yourself and lower when you are resting. Some things that can cause blood pressure to temporarily rise include;

  • Stress
  • Smoking
  • Cold temperatures
  • Exercise
  • Coffee
  • Certain medicines

Therefore, try to avoid as many of these factors as you can when taking your blood pressure. Also, blood pressure can fluctuate during the day, so try to measure your blood pressure at about the same time each day. 

Before taking your blood pressure:

  • Find a quiet place 
  • Make sure that you are comfortable and relaxed 
  • Follow the instructions carefully.

When you buy a home blood pressure monitor, make sure:

  • It is validated – there is a link below to a list of internationally validated devices.
  • The device is automatic, not manual, and has memory storage (so you can record your readings over time).
  • The cuff goes over your arm (not your wrist or fingers) and also that the cuff fits your arm. If the cuff is too large or too small, the reading won’t be accurate.
  • The numbers on the dial or display are large enough so you can read them clearly.
  • If unsure about a particular device, ask your pharmacist or doctor for advice.

More info:

List of validated home blood pressure measurement devices, from the British and Irish Hypertension Society

Measuring your blood pressure at home—Heart Foundation

Check Your Blood Pressure—Heart Research Institute

How to measure home blood pressure, from the Royal Australian College of GPs

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