Blood is circulated around the body by the pumping function of the heart. Blood pressure refers to the force exerted by the body's blood pushing against the walls of the blood vessels (specifically the artery), as it circulates around the body.
There are 2 components to blood pressure. The higher number is called 'systolic blood pressure', which refers to the pressure in the arteries when the heart contracts, pushing out blood. The lower number is called 'diastolic blood pressure', referring to the pressure in the arteries when the heart relaxes.
Blood pressure does not stay constant through the day. It can increase in response to excitement, physical exertion and stress. It can decrease in response to rest and sleep.
Blood pressure is measured in the clinic using a sphygmomanometer, or at home using an electronic blood pressure device. To ensure accurate blood pressure readings at home, some tips include
- Rest for around 5 minutes prior to blood pressure taking
- Sit upright in a comfortable position
- Wrap the blood pressure cuff snug around your bare left arm
- Rest the left arm on a table, at the level of the heart
- Relax and do not talk while the blood pressure is being taken
The current cut-offs for normal, healthy systolic and diastolic blood pressure is <120mmHg and <80mmHg respectively. Persistently elevated blood pressure beyond the defined normal limits, is known as hypertension. Hypertension is a major risk factor for many diseases.
According to the Singapore National Population Health Survey 2020, over one in three (35.5%) Singapore residents aged 18 to 74 years had hypertension during the period 2019-2020, a sharp increase from the 24.2% in 2017.
The table below shows the categories of blood pressure in adults aged >18 years old.
| Categories of Blood Pressure in Adults (>18 years old) | | | |
| | Blood Pressure Level (mmHg) | | |
| | Systolic | | Diastolic |
| Normal | <120 | | <80 |
| Elevated Blood Pressure | 120 – 129 | AND | <80 |
| Hypertension | | | |
| Stage 1 Hypertension | 130 - 139 | OR | 80 – 89 |
| Stage 2 Hypertension | ≥140 | OR | ≥90 |
(Source: American College of Cardiology High Blood Pressure Guideline 2017)
The causes of hypertension are varied and often multi-factorial.
They include:
- Non-modifiable risk factors (Factors you cannot control)
- Advancing age
- Family history of hypertension
- Modifiable risk factors (Factors you can control)
- Smoking
- Excessive alcohol intake
- Obesity
- Physical inactivity
- High salt intake in diet
- Side effects from medications (such as long-term steroid use)
- Secondary to other medical conditions (such as certain hormonal imbalances)
Hypertension has been termed the 'silent killer', as it is largely asymptomatic. In patients with severe hypertension, they might report symptoms such as blurred vision, headache, dizziness.
If left uncontrolled, long-term hypertension is a major risk factor for many diseases. They include
Hypertension is treated using a multi-pronged approach. Patients are advised to stop smoking, increase exercise, lose weight, reduce salt intake and manage stress.
Should lifestyle changes do not adequately lower blood pressure, medications are often necessary to maintain blood pressure in the healthy range. Many classes of medications are available for lowering blood pressure. Your doctor will carefully choose the right blood pressure lowering medication according to each patient's unique characteristics.
