orthostatic hypotension

(redirected from Orthostasis)
Also found in: Dictionary, Thesaurus.

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

 [hi″po-ten´shun]
diminished tension; lowered blood pressure. A consistently low blood pressure (systolic pressure less than 100 mm of mercury) usually is no cause for concern. In fact, low blood pressure often is associated with long life. However, extremely low blood pressure may be a sign of a serious condition such as shock, massive hemorrhage, hypovolemia, or severe dehydration from nausea and vomiting. In shock there is a disproportion between the blood volume and the capacity of the circulatory system, resulting in greatly reduced blood pressure. Hypotension may also be associated with addison's disease or inadequate thyroid function, but in both cases the primary disease produces so many other symptoms that the hypotension is not a major focus for concern.
orthostatic hypotension (postural hypotension) a fall in blood pressure (usually defined as a 20 to 30 point change in pulse or blood pressure), associated with dizziness, syncope, and blurred vision, occurring when a person goes from lying down or sitting to standing; it can be acquired or idiopathic, transient or chronic, and may occur alone or secondary to a disorder of the central nervous system such as the shy-drager syndrome.
supine hypotension vena caval syndrome.

or·tho·stat·ic hy·po·ten·sion

a form of low blood pressure that occurs in a standing posture.

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.

or·tho·stat·ic hy·po·ten·sion

(ōr-thō-statik hīpō-tenshŭn)
A form of low blood pressure that occurs in a standing patient.
Synonym(s): postural hypotension.

or·tho·stat·ic hy·po·ten·sion

(ōr-thŏ-statik hīpō-tenshŭn)
A form of low blood pressure that occurs in a standing patient.
Synonym(s): postural hypotension.
References in periodicals archive ?
Throughout this time, he continued to be followed by the renal service for symptomatic orthostasis thought to be caused by RSWS.
Alpha-blockers are effective, but are associated with orthostasis and syncopal events.
Results showed that CCC drops decreased the orthostatic fall in blood pressure, especially affecting diastolic blood pressure after 1 minute of orthostasis in all dosages as compared to placebo.
Those with VAD showed limited impairment in Valsalva ratio and orthostasis tests, whereas the only impairment found in patients with AD was on the orthostasis test.
Our prior work indicates that individuals with stroke and orthostasis are more likely to sustain a fall [28].
Parameters regarding safe and effective exercise include: Borg RPE scale of no greater than 13/20 without onset of signs and symptoms of angina, electrocardiogram (ECG) changes including ST shifts no > 1 mm and/or no increasing ventricular arrhythmias, dyspnea no greater than 5/10, claudication no greater than 2/4, decreased oxygen saturation, orthostasis, ataxia, and significant changes in systolic blood pressure.
First, diurnal fluctuation in albumin excretion has been established to range between 20% and 50%, (5, 33), with the lowest excretion during nocturnal recumbence and in the morning, and higher excretion during daytime owing primarily to orthostasis and higher GFR (34).
Hyponatremia in congestive heart failure: implications for neurohumoral activation and responses to orthostasis. J Clin Endocrinol Metab 1984; 59: 924-30.
Blood pressure was 130/80 mm/Hg, without orthostasis, respiratory rate 17 per minute and heart rate 85 per minute.
You are considering whether or not this change in blood pressure represents orthostasis and if you should do anything.
On examination: T: 97.6, HR: 115/min, BP: 105/50, no orthostasis, SP[O.sub.2]: 100% in room air and RR: 18/min.
Side effects with these drugs are nausea, daytime sleepiness, headache and orthostasis, but they are safer than the ergot-derived dopamine agonists, such as bromocriptine and cabergoline.