orthostatic hypotension - definition of orthostatic hypotension in the Medical dictionary - by the Free Online Medical Dictionary, Thesaurus and Encyclopedia.

Orthostatic Hypotension

Definition

Orthostatic hypotension is an abnormal decrease in blood pressure when a person stands up. This may lead to fainting.

Description

When a person stands upright, a certain amount of blood normally pools in the veins of the ankles and legs. This pooling means that there is slightly less blood for the heart to pump and causes a drop in blood pressure. Usually, the body responds to this drop so quickly, a person is unaware of the change. The brain tells the blood vessels to constrict so they have less capacity to carry blood, and at the same time tells the heart to beat faster and harder. These responses last for a very brief time. If the body's response to a change in vertical position is slow or absent, the result is orthostatic hypotension. It is not a true disease, but the inability to regulate blood pressure quickly.

Causes and symptoms

Orthostatic hypotension has many possible causes. The most common cause is medications used to treat other conditions. Diuretics reduce the amount of fluid in the body which reduces the volume of blood. Medicines used to expand the blood vessels increase the vessel's ability to carry blood and so lower blood pressure.

If there is a severe loss of body fluid from vomiting, diarrhea, untreated diabetes, or even excessive sweating, blood volume will be reduced enough to lower blood pressure. Severe bleeding can also result in orthostatic hypotension.

Any disease or spinal cord injury that damages the nerves which control blood vessel diameter can cause orthostatic hypotension.

Symptoms of orthostatic hypotension include faintness, dizziness, confusion, or blurry vision, when standing up quickly. An excessive loss of blood pressure can cause a person to pass out.

Diagnosis

When a person experiences any of the symptoms above, a physician can confirm orthostatic hypotension if the person's blood pressure falls significantly on standing up and returns to normal when lying down. The physician will then look for the cause of the condition.

Treatment

When the cause of orthostatic hypotension is related to medication, it is often possible to treat it by reducing dosage or changing the prescription. If it is caused by low blood volume, an increase in fluid intake and retention will solve the problem.

Medications designed to keep blood pressure from falling can be used when they will not interfere with other medical problems.

When orthostatic hypotension cannot be treated, the symptoms can be significantly reduced by remembering to stand up slowly or by wearing elastic stockings.

Prognosis

The prognosis for people who have orthostatic hypotension depends on the underlying cause of the problem.

Prevention

There is no way to prevent orthostatic hypotension, since it is usually the result of another medical condition.

Resources

Organizations

National Heart, Lung and Blood Institute. P.O. Box 30105, Bethesda, MD 20824-0105. (301) 251-1222. http://www.nhlbi.nih.gov.

National Organization for Rare Disorders. P.O. Box 8923, New Fairfield, CT 06812-8923. (800) 999-6673. http://www.rarediseases.org.

hypotension /hy·po·ten·sion/ (-ten´shun) abnormally low blood pressure.

orthostatic hypotension a fall in blood pressure associated with dizziness, blurred vision, and sometimes syncope, occurring upon standing or when standing motionless in a fixed position.

orthostatic hypotension

A form of low blood pressure precipitated by moving from a lying or sitting position to standing up straight. Also called postural hypotension.

orthostatic hypotension,

abnormally low blood pressure that occurs when an individual suddenly assumes the standing posture. It can produce dizziness and fainting. Also called postural hypotension.

hypotension (hī´pōten´sh

n),

n the presence of abnormally low blood pressure.

hypotension, orthostatic (postural)

n the plummeting of blood pressure that occurs when standing; dizziness and fainting may result.

orthostatic hypotension

Clinical medicine An abrupt ↓ in BP which occurs either when one stands up or when one remains in for a prolonged period of time in an erect position Clinical Dizziness, faintness, syncope, dim or tunnel vision–↓ cerebral blood flow; Sx typically improve with recumbency; OH occurs in normal healthy people who rise quickly from a chair, especially after a meal Etiology Autonomic failure, which may be 1º, or 2º to sympatholytic drugs, or irritation of the sympathetic nervous system, as in DM and late syphilis, where sympathetic vasoconstrictor fibers attempt to compensate for effects of gravity. See Autonomic failure.