Postural Hypotension (Orthostatic Hypotension) - Causes, Symptoms and Management

Postural hypotension, also known as orthostatic hypotension, refers to a drop in blood pressure (≥ 20 mm Hg systolic and/or ≥10 mmHg diastolic) that occurs within 3 minutes of standing.

Low blood pressure (hypotension) is a state where not enough blood (carrying oxygen) flows to vital organs such as the brain. It is mainly for this reason that one may experience dizziness.

Normal blood pressure is below 130/80 mmHg. The first reading measures systolic pressure or the amount of blood pressure when the heart is beating (squeezing the blood). The second reading measures diastolic pressure or the amount of blood pressure when the heart is at rest.

Some doctors consider blood pressure to be low when it is below 90/60 mmHg. However, there is no specific number at which day-to-day blood pressure is considered too low as long as it does not cause noticeable signs and symptoms.

People who are physically fit sometimes have lower blood pressure. And some people have naturally low blood pressure, with no ill effects.

Postural hypotension is an abnormal fall in blood pressure within three minutes of standing upright from lying or sitting. This happens due to the pooling of blood in the legs as a result of gravity. For the elderly, such dizziness may potentially result in falls, and if serious, may lead to hospitalisation or even death. Getting up slowly may help to reduce the sudden drop in blood pressure.

A person with low blood pressure (postural hypotension) may sometimes experience dizzy spells when standing up too quickly. However, that usually disappears after a few seconds, as soon as your body has adjusted to the changes in position and blood pressure, and when normal blood flow has been restored to your brain.

A drop in blood pressure will reduce the flow of blood to the brain. You may experience symptoms such as:

• Dizziness
• Light-headedness
• Possible mental confusion
• Fainting
• Muscle tremors
• Nausea
• Blurry vision
• Poor concentration
• Hands feeling cold and clammy
• Sudden pale skin
• Rapid and shallow breathing
• Tiredness

These low blood pressure symptoms occur when there are inadequate blood flows to your vital organs.

What are "Vaso-Vagal" Attacks?

In addition, a person with low blood pressure may feel faint when faced with certain triggers such as the sight of blood, the feeling of pain and emotions. This is known as a "vaso-vagal" attack, another type of transient low blood pressure.

For such people, the triggers will lead to an unusual slowing of the heart and dilatation of the blood vessels, and result in a drop in blood pressure; thus making one feels faint (known as "syncopy").

Postural hypotension and vaso-vagal attacks are very common, and most do not need any treatment as they are usually temporary. If dizziness is felt, sitting or stooping down often helps. Sometimes, such low blood pressure is caused by a sudden loss of blood volume, such as dehydration from severe diarrhoea, or any high blood pressure (hypertension) medication, especially if one has just started on the medication. Older people are more prone to this.

However, if you are not taking any high blood pressure medication and yet experience persistent dizzy or fainting spells, there may be other underlying medical problems which require further investigations.

Low blood pressure (hypotension) with these signs and symptoms requires medical attention:

• Dizziness
• Fainting
• Poor concentration
• Blurred vision
• Nausea
• Hands feeling cold and clammy
• Sudden pale skin
• Rapid and shallow breathing
• Tiredness

If your symptoms persist, you are advised to see a doctor. If you are not taking any high blood pressure medication and yet experience persistent dizzy or fainting spells, there may be other underlying medical problems which require further investigations.

Low blood pressure may be caused by many underlying medical conditions. The following conditions can be serious and may lead to shock. It is known as "shock" when the drop in blood pressure is severe and persistent. If it is not treated immediately, shock can cause permanent damage to the vital organs and may result in death.

Heart Disease

Blood pressure may fall if the heart is not effective in pumping blood. Some of these heart conditions can be life-threatening. These conditions include abnormal heart rhythm (arrhythmia), heart attack (myocardial infarction), heart valve defects and heart failure.

Decrease in Blood Volume

The decrease of blood volume in the body can be the result of the loss of body fluids or blood. Severe blood loss caused by external injuries such as an accident, or internal bleeding such as bleeding from stomach ulcers or very heavy menses, can cause low blood pressure. Loss of body fluids from conditions associated with severe vomiting and diarrhoea is another common reason for low blood pressure.

Severe Infection

When bacteria leave the original infection site (most often in the lungs, abdomen or urinary tract) and enter the bloodstream, it results in a severe infection known as sepsis. The bacteria release toxins that cause dilation of blood vessels, leading to a profound and rapid decline in blood pressure.

Hormonal Problems

Our body's endocrine system consists of hormone-producing glands, e.g. thyroid gland, adrenal gland, pancreas, etc. An underactive thyroid (hypothyroidism) may cause low blood pressure. A low cortisol ("stress hormone") level which is produced by the adrenal glands can cause low blood pressure as well. However, this is not a common cause of low blood pressure.

Severe Allergic Reaction

There are various types of allergic reaction. These allergic reactions can occur in some people as a result of allergies to drugs (e.g. antibiotics), food such as peanuts or insect stings (e.g. bees or wasps). The most serious reaction is known as anaphylaxis, which can cause a sudden fall in blood pressure and can be fatal.

To measure your blood pressure:

1. Sit in a comfortable position.
2. Place your left arm on a table or desk.
3. Wrap the digital blood pressure device snugly around the upper part of bare arm and press the 'start' button.
4. Do not move your arm until the measurement has been taken and reflected on display screen.

A common complication of postural hypotension is frequent falls resulting in serious injuries. Hence the management strategies listed below aim to improve ability to cope with postural hypotension faced in daily activities and routines.

Please consult your doctor on suitable medications which can help control postural hypotension.

Management Strategies

1. Sleep with head elevated 20 to 30 degrees: This helps reduce the sudden drop in blood pressure when getting up.

2. Change posture slowly from lying to sitting: Take your time when transitioning between positions to allow your body to adjust.

3. Sit by edge of bed for a few minutes before getting up: Hold on to a fixture when getting up. Sit back down if you feel unwell after changing position.

4. Perform simple leg or feet exercises: For example, calf raises or march on the spot in standing (holding on to fixture). These exercises help improve blood circulation.

5. Avoid bending down to pick things up: Use a long-handled reacher to avoid sudden changes in position that can trigger symptoms.

6. Keep bathroom airy with ample ventilation: Good ventilation helps prevent dizziness in enclosed spaces.

7. Perform showering and dressing in seated position: This reduces the risk of falls whilst performing daily activities.

The good news is that most low blood pressure cases do not need any treatment if there are no symptoms. Serious low blood pressure cases are uncommon. However, if your symptoms persist, you are advised to see a doctor.