| |
The heart pumps blood around the body through the blood vessels. Blood pressure is the amount of force exerted on the artery walls by the pumping blood. Blood pressure varies according to environmental demands. For example, it rises during physical exertion and drops in extreme heat.
Hypotension, or low blood pressure, means that the pressure of blood circulating around the body is lower than normal or lower than expected given the environmental conditions. However, ‘hypotension’ is a relative term – an individual may have low blood pressure compared to others of similar physical characteristics, but may be perfectly healthy.
Low blood pressure is only a problem if it has a negative impact on the body. For example, vital organs (particularly the brain) may be starved of oxygen and nutrients if the blood pressure is too low for that particular individual.
Symptoms
Substantial blood loss can cause a sudden drop in blood pressure (shock). The most dramatic symptom of sudden hypotension is unconsciousness. Usually, low blood pressure develops over time. Symptoms include:
- Light-headedness, when standing from a sitting or lying position
- Unsteadiness
- Dizziness
- Weakness
- Blurred vision
- Fatigue
- Fainting.
A range of causes
Blood pressure is measured using a device known as a sphygmomanometer. If the measurement drops 30mmHg below the person’s usual blood pressure, this is considered to be hypotension.
Low blood pressure has many different causes including:
- Emotional stress, fear, insecurity or pain (the most common causes of fainting)
- Dehydration, which reduces blood volume
- The body’s reaction to heat, which is to shunt blood into the vessels of the skin, leading to dehydration
- Blood donation
- Internal bleeding, such as a perforated stomach ulcer
- Blood loss from trauma, such as a road accident or deep cut
- Pregnancy
- Medications for high blood pressure
- Diuretics, which produce fluid loss
- Medications for depression
- Medications for certain heart conditions
- Allergic reaction to certain drugs or chemicals
- Some forms of infection, such as toxic shock syndrome
- Heart disease, which can hamper the pumping action of the heart muscle
- Some nervous system disorders, such as Parkinson’s disease
- Addison’s disease (where the adrenal glands fail to produce sufficient blood-pressure-maintaining hormones).
Orthostatic hypotension
Generally, when you stand upright from a sitting or lying position, the blood vessels in your body respond to gravity by constricting. This increases blood pressure. Orthostatic hypotension means that the blood vessels don’t adjust to a standing position and, instead, allow the blood pressure to drop, resulting in a feeling of light-headedness.
Causes include:
- Nervous system diseases, such as neuropathy
- Prolonged bed rest
- Dehydration
- Irregular heart beat (heart arrhythmia).
Treatment
Treatment for hypotension depends on the cause. For example, the dosages of existing medications may need to be altered or a bleeding stomach ulcer surgically repaired. If no particular cause can be found, drugs may be used to raise blood pressure. In extreme cases, a lower body pressure suit may be required.
Where to get help
Things to remember
- Hypotension, or low blood pressure, means that the pressure of blood circulating around the body is lower than normal or lower than expected.
- Low blood pressure is only a problem if it has a negative impact on the body and produces symptoms.
- Some causes of hypotension include blood loss, dehydration and certain medications, such as antihypertensive drugs.
|  |
|
| |
You might also be interested in:
Addison's disease.
Blood pressure (high) - hypertension.
Blood pressure explained.
Circulatory system.
Dizziness and vertigo.
Heart arrhythmia and palpitations.
Want to know more?
Go to More information for support groups, related links and references.
This page has been produced in consultation with, and approved by:
Heart Research Centre
|
|
Copyight © 1999/2008 State of Victoria. Reproduced from the Better Health Channel (www.betterhealth.vic.gov.au) at no cost with permission of the Victorian Minister for Health. Unauthorised reproduction and other uses comprised in the copyright are prohibited without permission.
|
•
|
This Better Health Channel fact sheet has passed through a rigorous approval process. For the latest updates and more information visit www.betterhealth.vic.gov.au.
|
|
|
Last updated: November 2007
© State of Victoria
Linking to the Better Health Channel
It's easy to link to this fact sheet |
Close
If you would like to link to this fact sheet on your website, simply copy the code below and add it to your page:
<a href="http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Hypotension?OpenDocument">Blood pressure (low) - hypotension - Better Health Channel</a><br/>
Hypotension, or low blood pressure, means that the pressure of blood as it circulates around the body is lower than normal or lower than expected. Hypotension is only a problem if it has a negative impact on the body...
The link should appear like this:
Blood pressure (low) - hypotension - Better Health ChannelHypotension, or low blood pressure, means that the pressure of blood as it circulates around the body is lower than normal or lower than expected. Hypotension is only a problem if it has a negative impact on the body...
Quality assurance
This fact sheet, like all fact sheets on the Better Health Channel, has passed through a rigorous and exhaustive approval process. It is also regularly updated. For more information see our quality assurance page.
|
|
