Hypotension




What Is Hypotension?

Hypotension is abnormally low blood pressure. Normal blood pressure is a reading of less than 120/80 mmHg (mmHg = millimeters of mercury, a unit for measuring pressure). Hypotension is blood pressure that is lower than 90/60 mmHg. Some people have low blood pressure all the time. They have no signs or symptoms and their low readings are normal for them. In other people, blood pressure drops below normal because of some event or medical condition. Hypotension is a medical concern only if it causes signs and/or symptoms such as dizziness, fainting, or, in extreme cases, shock.

Other Names for Hypotension Causes, incidence, and risk factors

Blood pressure that is borderline low for one person may be normal for another. The most important factor is how the blood pressure changes from the normal condition. Most normal blood pressures fall in the range of 90/60 millimeters of mercury (mm Hg) to 130/80 mm Hg. But a significant drop, even as little as 20 mm Hg, can cause problems for some people. There are three main types of hypotension:
  • Orthostatic hypotension, including postprandial orthostatic hypotension.
  • Neurally mediated hypotension (NMH)
  • Severe hypotension brought on by a sudden loss of blood (shock)
Orthostatic hypotension is brought on by a sudden change in body position, usually when shifting from lying down to standing. This type of hypotension usually lasts only a few seconds or minutes. If this type of hypotension occurs after eating, it is called postprandial orthostatic hypotension. This form most commonly affects older adults, those with high blood pressure, and persons with Parkinson's disease. NMH most often affects young adults and children. It occurs when a person has been standing for a long time. You might feel dizzy, faint, or have an upset stomach. Children usually outgrow this type of hypotension. Severe hypotension starves your body of oxygen, which can cause damage to the heart, brain, and other organs. This type of hypotension can be life threatening if not immediately treated.

Low blood pressure is commonly caused by drugs such as:
  • Medications used for surgery
  • Anti-anxiety medications
  • Heart medicines, including those used to treat high blood pressure and coronary heart disease
  • Diuretics
  • Certain antidepressants
  • Pain killers
  • Alcohol
Other causes of low blood pressure include:
  • Dehydration
  • Heart failure
  • Heart attack
  • Changes in heart rhythm (arrhythmias)
  • Fainting
  • Anaphylaxis (a life-threatening allergic response)
  • Shock (from severe infection, stroke, anaphylaxis, major trauma, or heart attack)
  • Advanced diabetes
Symptoms

Symptoms may include:
  • Blurry vision
  • Confusion
  • Dizziness
  • Fainting (syncope)
  • Lightheadedness
  • Sleepiness
  • Weakness
A sudden drop in blood pressure that causes a sudden, brief loss of consciousness (syncope) can lead to accidents, including falls. Falls are particularly dangerous for older adults. Fall-related injuries, such as a broken hip, can dramatically impact a person's quality of life.

Treatment

Hypotension in a healthy person that does not cause any problems usually doesn't require treatment. If you have signs or symptoms of low blood pressure, you may need treatment. Treatment depends on the cause of your low blood pressure. Severe hypotension caused by shock is a medical emergency. You may be given blood through a needle (IV), medicines to increase blood pressure and improve heart strength, and other medicines, such as antibiotics. For more details, see the article on shock.

If you have orthostatic hypotension caused by medicines, your doctor may change the dose or switch you to a different drug. DO NOT stop taking any medicine before talking to your doctor. Other treatments for orthostatic hypotension include increasing fluids to treat dehydration or wearing elastic hose to boost blood pressure in the lower part of the body. Those with NMH should avoid triggers, such as standing for a long period of time. Other treatments involve drinking plenty of fluids and increasing the amount of salt in your diet. (Ask your doctor about specific recommendations.) In severe cases, medicines such as fludrocortisone may be prescribed.

Prevention

If you have low blood pressure, your doctor may recommend certain steps to prevent or reduce your symptoms. This may include: Drinking plenty of fluids Avoiding alcohol Getting up slowly after sitting or lying down Using compression stockings to increase blood pressure in the legs Avoiding standing for a long time (if you have NMH).
Credit: National Institute of Health.
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