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Postural Hypotension / Orthostatic Hypotension

Definition:
Orthostatic hypotension — also called postural hypotension — is a form of low blood pressure that happens when you stand up from sitting or lying down. Orthostatic hypotension can make you feel dizzy or lightheaded, and maybe even faint.

Orthostatic hypotension can happen to anyone but is more common in older adults. More than 15 percent of those 65 and older have orthostatic hypotension. Orthostatic hypotension is often mild, lasting only a few seconds or a few minutes after standing. However, orthostatic hypotension can be a sign of more-serious problems, so talk to your doctor if you frequently feel lightheaded when standing up.

If you have mild orthostatic hypotension, you may not need treatment. The treatment for more severe cases of orthostatic hypotension depends on what's causing your episodes of low blood pressure.

Causes:
When you stand up, gravity causes blood to pool in your legs. This decreases blood pressure because there's less blood circulating back to your heart to pump. Normally, special cells (baroreceptors) next to your heart and neck arteries sense this lower blood pressure and counteract it by triggering your heart to beat faster and pump more blood, which stabilizes blood pressure. In addition, these cells cause blood vessels to narrow, which increases resistance to blood flow and increases blood pressure.

Orthostatic or postural hypotension occurs when something interrupts the body's natural process of counteracting low blood pressure. Orthostatic hypotension can be caused by many different things, including :

  • Dehydration. Fever, vomiting, not drinking enough fluids, severe diarrhea and strenuous exercise can all lead to dehydration. When you become dehydrated, your body loses more water, and often sodium, than you take in. Even mild dehydration can cause weakness, dizziness and fatigue. Far more serious is hypovolemic shock, a life-threatening complication of dehydration. It occurs when low blood volume causes a sudden drop in blood pressure and a corresponding reduction in the amount of oxygen reaching your tissues. If untreated, severe hypovolemic shock can cause death within a few minutes or hours.
  • Medications. Many drugs can cause orthostatic hypotension, including diuretics (water pills) and other drugs that treat high blood pressure; heart medications, such as beta blockers; drugs for Parkinson's disease; tricyclic antidepressants; sildenafil (Viagra), particularly in combination with nitroglycerin; narcotics; and alcohol. Other prescription and over-the-counter medications may cause low blood pressure when taken in combination with medications used to treat high blood pressure.
  • Heart problems. Some heart conditions that can lead to low blood pressure include extremely low heart rate (bradycardia), heart valve problems, heart attack and heart failure. These conditions may cause orthostatic hypotension because they prevent your body from being able to circulate enough blood.
  • Diabetes. Untreated diabetes can cause dehydration by causing frequent urination. This can trigger orthostatic hypotension. In addition, diabetes can damage the nerves that help send signals regulating blood pressure.
  • Nervous system disorders. Some diseases, such as Parkinson's disease, multiple system atrophy (Shy-Drager syndrome) and amyloidosis, can disrupt your body's normal blood pressure regulation system.

Risk Factor :
The risk factors for orthostatic hypotension include :

  • Age. Most orthostatic hypotension occurs in those 65 and older. As your body ages, the ability of special cells (baroreceptors) near your heart and neck arteries to regulate blood pressure can be slowed. Also, when you age, it may be harder for your heart to beat faster and compensate for drops in blood pressure.
  • Medications. People who take certain medications, such as high blood pressure medication, have a greater risk of orthostatic hypotension.
  • Certain diseases. Parkinson's disease and some heart conditions put you at a greater risk of developing low blood pressure.
  • Heat exposure. Being in a hot environment can cause you to sweat and, possibly, cause dehydration, which can lower your blood pressure and trigger orthostatic hypotension.
  • Bed rest. If you have to stay in bed a long time because of an illness, you may become weak. When you try to stand up, you may experience orthostatic hypotension.
  • Crossing your legs at the knees. Sitting for prolonged periods with your legs crossed at the knees (versus ankle across the knee as men are prone to do) presses on veins, encouraging blood to pool in the leg.
  • Pregnancy. Because a woman's circulatory system expands rapidly during pregnancy, blood pressure is likely to drop. This could cause blood pressure to drop enough to cause orthostatic hypotension when standing up quickly.

When to seek medical advice :
Occasional dizziness or lightheadedness may be relatively minor — the result of mild dehydration, low blood sugar, or too much time in the sun or a hot tub, for example. Still, it's important to see your doctor if you experience frequent symptoms of orthostatic hypotension because they sometimes can point to more-serious problems. It can be helpful to keep a record of your symptoms, when they occur and what you were doing at the time. If these occur at times that may endanger you or others, discuss this with your doctor.

Symptoms:
The most common symptom of orthostatic hypotension is feeling lightheaded or dizzy when you stand up after sitting or lying down. This feeling, and other symptoms, usually happens shortly after standing up and lasts a few seconds or minutes. Signs and symptoms of orthostatic hypotension include :

  • Feeling lightheaded or dizzy after standing up
  • Blurry vision
  • Weakness
  • Fainting (syncope)
  • Confusion
  • Nausea
  • Headache

Diagnosis:
The goal in evaluating orthostatic hypotension, as with all forms of low blood pressure, is to find the underlying cause. This helps determine the correct treatment and identify any heart, brain or nervous system problems that may be responsible for your low blood pressure. To help reach a diagnosis, your doctor may recommend one or more of the following :

  • Blood pressure monitoring. Your doctor will measure your blood pressure and compare your sitting blood pressure with your blood pressure when you stand.
  • Blood tests. These can provide a certain amount of information about your overall health as well as whether you have low blood sugar (hypoglycemia) or a low number of red blood cells (anemia), both of which can cause lower than normal blood pressure.
  • Electrocardiogram (ECG). This noninvasive test detects irregularities in your heart rhythm, structural abnormalities in your heart, and problems with the supply of blood and oxygen to your heart muscle.
  • Echocardiogram. An echocardiogram uses sound waves to produce images of your heart that may show abnormalities in your heart muscle or valves.
  • Stress test. Some heart problems that can cause low blood pressure are easier to diagnose when your heart is working harder than when it's at rest. During a stress test, you'll exercise, such as walking on a treadmill. Or, you may be given medication to make your heart work harder if you're unable to exercise. When your heart is working harder, your heart will be monitored with electrocardiography or echocardiography. Your blood pressure also will be monitored.
  • Tilt table test. A tilt table test evaluates how your body reacts to changes in position. During the test, you lie on a table that begins flat and then tilts to raise the upper part of your body, which simulates the movement from a prone to a standing position. Your blood pressure is taken frequently as the table is tilted.
  • Ambulatory blood pressure and ECG recording. This test entails wearing a blood pressure cuff for 24 hours with periodic automatic recording of your blood pressure. You'll also be fitted with a monitor to allow a continuous ECG reading. You will be asked to keep a diary and hopefully capture an episode of intermittent orthostatic hypotension.

Complications :
While mild forms of orthostatic hypotension may be a nuisance, more serious complications are possible, especially in older adults. These complications include :

  • Falls. Falling down as a result of fainting (syncope) is a common complication in people with orthostatic hypotension.
  • Stroke. The swings in blood pressure when you stand and sit as a result of orthostatic hypotension can be a risk factor for stroke.
  • Mental impairment. Some research has indicated that orthostatic hypotension can damage parts of the brain, increasing the risk of some forms of dementia and other brain disorders.

Treatment:
The treatment for orthostatic hypotension depends on the underlying cause. Your doctor will try to address the underlying health problem — dehydration or heart failure, for example — rather than low blood pressure itself. One of the simplest treatments is to sit or lie down immediately after feeling lightheaded upon standing; your symptoms of orthostatic hypotension usually disappear.

When low blood pressure is caused by medications, treatment usually involves changing the dose of the medication or stopping it entirely. There are usually several options for treating orthostatic hypotension, including:

  • Lifestyle changes. Drinking plenty of fluids, such as water; drinking little to no alcohol; avoiding walking during hot weather; and standing up slowly are things your doctor may suggest. Your doctor may also suggest exercise programs that strengthen your calf muscles. If you don't also have high blood pressure, your doctor might suggest increasing the amount of salt in your diet.
  • Compression stockings. The same elastic stockings and leotards commonly used to relieve the pain and swelling of varicose veins may help reduce the pooling of blood in your legs and reduce the symptoms of orthostatic hypotension.
  • Medications. Several medications, either used alone or together, can be used to treat orthostatic hypotension. For example, the drug fludrocortisone is often used to help boost your blood volume, which raises blood pressure. Doctors often use the drug midodrine to raise standing blood pressure levels. It works by restricting the ability of your blood vessels to expand, which raises blood pressure. Other drugs, such as pyridostigmine, nonsteroidal anti-inflammatory drugs (NSAIDs), caffeine and epoetin, are sometimes used, too, either alone or with other drugs.
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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