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With rising, a fall in blood pressure

Some people experience drops in blood pressure when they stand up. Falls are a risk. But there are often simple ways to counter the problem.

When we stand up, blood tends to pool in the lower half of our bodies, filling veins in the liver, intestines, and other abdominal organs, as well as those in the legs. The downward flow means there’s a danger of not enough blood reaching the brain, which can lead to a loss of consciousness. But adjustments occur that keep that from happening. Sensors in the aorta in the torso and in the carotid arteries in the neck trigger a response that revs up the “fight-or-flight” part of the nervous system and dials down the “rest-and-digest” part. The heart beats a little faster and stronger. Blood vessels constrict, squeezing blood into a tighter space. Blood flow and blood pressure stay more or less normal.

But with age and some diseases, these compensations for gravity’s effect on blood circulation may falter. The heart gets stiffer and weaker, so it doesn’t pump as well. Blood vessels get stiffer and less responsive. The sensors in the aorta and carotids become less sensitive, and the signals they send to the nervous system, less effective. As a result, some people experience sizable drops in blood pressure when they stand up, a condition known as orthostatic hypotension or, sometimes, postural hypotension. Hypo is Greek for under, and tension refers to blood pressure.

Causes

Conditions that affect the nervous system, like Parkinson’s disease and some forms of dementia (Lewy body disease, in particular), can cause orthostatic hypotension, as can nerve damage from diabetes (diabetic neuropathy). Orthostatic hypotension is also a side effect of many medications, including those prescribed to lower high blood pressure.

It can come on suddenly from dehydration caused by vomiting, diarrhea, fever, or lack of fluid intake. Blood loss can also cause acute cases.

Studies suggest that about 20% of people over 65 are chronically affected by orthostatic hypotension, and the prevalence increases to 30% in people over 75 and may be as high as 50% among those in nursing homes. In some cases, though, symptoms are mild or absent.

When people do have symptoms from orthostatic hypotension, it’s because not enough blood is reaching the brain. They feel lightheaded or dizzy. Vision may become gray or dark. In extreme cases, people faint.

Orthostatic hypotension: When your blood pressure falls when you stand up

illustration of circulatory system showing causes of orthostatic hypotension

May cause falls

Orthostatic hypotension is associated with falls, yet the data are surprisingly inconsistent, with some studies finding no connection.

How orthostatic hypotension is defined and measured may have something to do with that. Doctors currently define orthostatic hypotension as a drop of at least 20 mm Hg in systolic blood pressure (the top number) or a drop of 10 mm Hg in diastolic blood pressure (the bottom number) within three minutes of standing up. But researchers have reported that big drops in blood pressure within 15 seconds of standing up are more closely associated with a history of falls than reductions over three minutes. Instruments that measure blood pressure continuously may do a better job of detecting these very sudden drops of blood pressure upon standing up than conventional measuring devices.

Connected to high blood pressure

The relationship between high blood pressure, or hypertension, and orthostatic hypotension, has also caused some confusion. People with high blood pressure are more likely to be troubled by orthostatic hypotension. At first glance, that might not seem to make sense: if your blood pressure is high, that would seem to offer some protection against it getting too low when you stand up. But stiff blood vessels and less responsive pressure sensors play a role in causing both conditions, and in some cases, they may be just different aspects of the body’s inability to properly regulate blood pressure.

Studies have shown that people whose high blood pressure has been successfully controlled are less likely to be troubled by orthostatic hypotension. Harvard researchers reported findings in 2011 that suggested that people who have both high blood pressure and orthostatic hypotension may be at especially high risk of falling, and efforts to prevent falls should perhaps target this group.

On the other hand, people may develop orthostatic hypotension when they first start taking blood pressure medications, so doctors need to be careful and start patients on low doses. Some blood pressure drugs may be more of a problem than others. Diuretics (sometimes called water pills) decrease the volume of the blood in the body, which can reduce high blood pressure but may also tip some people into orthostatic hypotension.

One study published several years ago showed that ACE inhibitors (lisinopril, ramipril, others) seemed to protect people with high blood pressure from orthostatic hypotension. A potassium-sparing diuretic called spironolactone (sold as Aldactone and Aldactazide, as well as a generic) made the condition worse.

Orthostatic hypotension is easy to diagnose. Blood pressure is measured after you have been lying down for about five minutes and then after you stand up. Some research shows that even if you don’t have any symptoms, orthostatic hypotension increases your risk for falling and may be a sign of higher risk for heart attack and transient ischemic attacks (“mini-strokes”), so a doctor may recommend treatment even if you don’t have any symptoms.

What you can do about it

Many conditions are hard to treat or manage without taking a medication, but orthostatic hypotension isn’t one of them. There are numerous things you can try before medication. But you should talk to a doctor if you’re having problems with lightheadedness, dizziness, or other problems that could be related to orthostatic hypotension. The risk of falling is a serious matter.

Here are eight things you can do to counter orthostatic hypotension:

1. Take your time standing up. Move gradually from lying down to sitting to a standing position. This is especially important in the morning, when orthostatic hypotension is often the most pronounced.

2. Try these maneuvers. Wiggling your toes and flexing your feet before you stand up can help push blood back up to the heart and improve blood pressure. Squatting and stooping forward can temporarily increase blood pressure. Once you’re standing, crossing and tensing your legs may also improve blood flow and even out distribution of blood in the body. If you’ve been standing awhile, sitting down is a simple way to help your cardiovascular system maintain blood pressure.

3. Review your medications with your doctor and maybe make a change. Some drugs work by relaxing and widening blood vessels, which can trigger orthostatic hypotension or make it worse. Prime examples include the alpha blockers used to treat high blood pressure and prostate problems (tamsulosin, sold as Flomax, is an alpha blocker). Antihistamines and the tricyclic antidepressants (amitriptyline, nortriptyline, others) can also contribute to orthostatic hypotension.

4. Lift the head of your bed by 10 to 20 degrees. Sleeping with your head higher than your feet decreases the amount of blood passing through the kidneys. The kidneys don’t produce as much urine when they are processing less blood, so the body hangs on to more fluid, which keeps blood pressure higher.

5. Increase your fluid (and maybe your salt) intake. Dehydration from not drinking enough fluid is a common problem in older people. When the body gets “dried out,” blood pressure may drop because the volume of blood decreases. Poor kidney function sometimes contributes to this problem. Normally, we’re advised to cut back on salt because it increases the risk of high blood pressure, but if the problem is orthostatic hypotension, higher intake can help counter fluid loss and increase blood volume.

6. Drink coffee in the morning. The caffeine in coffee boosts blood pressure and may ease symptoms. Limiting intake to the morning can help keep the body sensitive to caffeine’s blood pressure–boosting effects.

7. Exercise more. Orthostatic hypotension sometimes goes away if people improve their cardiovascular fitness by getting more exercise. With regular exercise, the heart beats stronger and blood vessels become more flexible and responsive. Walking, biking, light swimming — anything that increases your heart rate will help improve cardiovascular fitness.

8. Wear compression stockings. Special stockings that apply pressure on the lower half of the body can keep blood from pooling in veins. But some experts say the stockings need to extend all the way up to the waist to be effective because more blood collects in the abdomen than in the legs. Many people find these stockings uncomfortable, so they’re among the last things to try.

Medications

If none of these countermeasures works, some cases of orthostatic hypotension can be treated with medication, although it is definitely a last resort and usually reserved for serious cases. Fludrocortisone, a corticosteroid, increases blood volume, and therefore blood pressure, by decreasing the amount of sodium that is excreted in urine. A different drug, midodrine, increases blood pressure by constricting blood vessels.

Posted by: Dr.Health

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