What You Need to Know
- Your blood pressure changes when you change position.
- When your heart contracts, it pushes blood into the arteries causing an increase in blood pressure (systolic pressure). When your heart relaxes and refills with blood, the pressure in the arteries decreases (diastolic pressure).
- Standing causes 500 to 700 ml of blood to pool in the legs, so there is less blood for the heart to pump. This results in a decrease in blood pressure.
- Special cells called baroreceptors (located close to the neck arteries) sense this decrease in blood pressure. They counteract by triggering the heart to beat faster and pump more blood in order to stabilize the blood pressure.
- Normally, the blood pressure response that occurs when an individual moves to a standing position is a small reduction in systolic blood pressure and a small increase in diastolic blood pressure (the two numbers that are measured). This imbalance lasts only for a few seconds as it adjusts to the new posture.
- Postural hypotension occurs when there is a significant decrease in the systolic and/or diastolic blood pressure when a person stands up. It usually occurs within three minutes of standing. Occassionally, people experience this after standing for 5 or more minutes. It is caused by abnormal blood pressure regulation and becomes more common with aging.
Symptoms of orthostatic (postural) hypotension include:
- The most common symptom is feeling light-headed or dizzy after standing up from a lying or sitting position. This usually lasts from a few seconds to minutes.
- Other symptoms include blurring of vision, loss of consciousness (syncope, fainting), and falls.
Causes of postural hypotension include:
- inadequate fluid intake or dehydration
- prolonged bed rest or deconditioning
- diabetes, Parkinson's disease
- heart failure or chronic kidney failure
- poorly controlled hypertension
To prevent postural hypotension:
- Drink enough fluids (1.5 – 2 litres or 6 – 8 glasses per day) to avoid dehydration.
- Have the health care provider review medications to identify any that can cause postural hypotension.
- When waking up in the morning, sit on the edge of the bed and do calf muscle exercises for 5 minutes before standing.
- Avoid quick position (postural) changes.
- If symptoms appear, sit down quickly and wait for them to subside.
- Postural hypotension tends to be worse in the morning, so plan activities for the afternoon or later in the day.
- Avoid prolonged standing, hot environments, and excessive alcohol use.
- Raise the head end of the bed to 15 to 20 degrees.
- Compression stockings that are applied up to thigh level may help to decrease the pooling of blood in the leg veins. Stockings should be measured by a health professional to ensure need and appropriate fit.
- Some people experience postural hypotension after meals. This is called post-prandial hypotension. If you have this, stay sitting for 30 minutes after eating.
When to Seek Medical Advice
If postural hypotension occurs, your family member should see their health care provider for medical advice to avoid complications like loss of consciousness and falls and to identify any underlying problems.
- The Mayo Clinic's explanation of orthostatic hypotension is well-organized and complete. It includes signs and symptoms, causes, and self-care.
National Institute of Neurological Disorders and Stroke
- This information page provides an overview of Orthostatic Hypotension.
National Heart Lung and Blood Institute (USA)
- This article describes how hypotension is treated.
WebMD Medical Reference
- Understanding Low Blood Pressure describes low blood pressure and discusses a number of causes.
The Merck Manual
- Overview of Low Blood Pressure in the Merck Manual Home Health Handbook discusses causes, symptoms and treatment.