Low blood pressure might seem desirable, and for some people, it causes no problems. However, for many people, abnormally low blood pressure (hypotension) can cause dizziness and fainting. In severe cases, low blood pressure can be life-threatening.
A blood pressure reading lower than 90 millimeters of mercury (mm Hg) for the top number (systolic) or 60 mm Hg for the bottom number (diastolic) is generally considered low blood pressure.
The causes of low blood pressure can range from dehydration to serious medical or surgical disorders. It's important to find out what's causing your low blood pressure so that it can be treated.
Source: http://www.mayoclinic.com
For some people, low blood pressure signals an underlying problem, especially when it drops suddenly or is accompanied by signs and symptoms such as:
Extreme hypotension can result in this life-threatening condition. Signs and symptoms include:
If you have indications of shock, seek emergency medical help.
If you have consistently low blood pressure readings but feel fine, your doctor is likely just to monitor you during routine exams.
Even occasional dizziness or lightheadedness may be a relatively minor problem â the result of mild dehydration from too much time in the sun or a hot tub, for example. Still, it's important to see your doctor if you have signs or symptoms of hypotension because they can point to more-serious problems. It can be helpful to keep a record of your symptoms, when they occur and what you're doing at the time.
Source: http://www.mayoclinic.com
Blood pressure is a measurement of the pressure in your arteries during the active and resting phases of each heartbeat.
Current guidelines identify normal blood pressure as lower than 120/80 mm Hg.
Throughout the day, blood pressure varies, depending on body position, breathing rhythm, stress level, physical condition, medications you take, what you eat and drink, and time of day. Blood pressure is usually lowest at night and rises sharply on waking.
What's considered low blood pressure for you may be normal for someone else. Most doctors consider blood pressure too low only if it causes symptoms.
Some experts define low blood pressure as readings lower than 90 mm Hg systolic or 60 mm Hg diastolic. If either number is below that, your pressure is lower than normal.
A sudden fall in blood pressure can be dangerous. A change of just 20 mm Hg â a drop from 110 systolic to 90 mm Hg systolic, for example â can cause dizziness and fainting when the brain fails to receive an adequate supply of blood. And big plunges, such as those caused by uncontrolled bleeding, severe infections or allergic reactions, can be life-threatening.
Conditions that can cause low blood pressure
Medical conditions that can cause low blood pressure include:
Some medications can cause low blood pressure, including:
Doctors often break down low blood pressure (hypotension) into categories, depending on the causes and other factors. Some types of low blood pressure include:
Low blood pressure on standing up (orthostatic, or postural, hypotension). This is a sudden drop in blood pressure when you stand up from a sitting position or after lying down.
Gravity causes blood to pool in your legs when you stand. Ordinarily, your body compensates by increasing your heart rate and constricting blood vessels, thereby ensuring that enough blood returns to your brain.
But in people with orthostatic hypotension, this compensating mechanism fails and blood pressure falls, leading to dizziness, lightheadedness, blurred vision and even fainting.
Orthostatic hypotension can occur for various reasons, including dehydration, prolonged bed rest, pregnancy, diabetes, heart problems, burns, excessive heat, large varicose veins and certain neurological disorders.
A number of medications also can cause orthostatic hypotension, particularly drugs used to treat high blood pressure â diuretics, beta blockers, calcium channel blockers and angiotensin-converting enzyme (ACE) inhibitors â as well as antidepressants and drugs used to treat Parkinson's disease and erectile dysfunction.
Orthostatic hypotension is especially common in older adults, but it also affects young, otherwise healthy people who stand up suddenly after sitting with their legs crossed for long periods or after squatting for a time.
It's also possible to have delayed orthostatic hypotension, with signs and symptoms developing 5 to 10 minutes after a change in posture. This might be a milder form of the condition, or it could be an early stage of it.
Low blood pressure after eating (postprandial hypotension). This sudden drop in blood pressure after eating affects mostly older adults.
Blood flows to your digestive tract after you eat. Ordinarily, your body increases your heart rate and constricts certain blood vessels to help maintain normal blood pressure. But in some people these mechanisms fail, leading to dizziness, faintness and falls.
Postprandial hypotension is more likely to affect people with high blood pressure or autonomic nervous system disorders such as Parkinson's disease.
Lowering the dose of blood pressure drugs and eating small, low-carbohydrate meals might help reduce symptoms.
Source: http://www.mayoclinic.com
The goal in testing for low blood pressure is to find the underlying cause. Besides taking your medical history, doing a physical exam and measuring your blood pressure, your doctor might recommend the following:
Electrocardiogram (ECG). During this painless, noninvasive test, soft, sticky patches (electrodes) are attached to the skin of your chest, arms and legs. The patches detect your heart's electrical signals while a machine records them on graph paper or displays them on a screen.
An ECG, which can be performed in your doctor's office, detects irregularities in your heart rhythm, structural abnormalities in your heart, and problems with the supply of blood and oxygen to your heart muscle. It can also tell if you're having a heart attack or have had one in the past.
Heart rhythm abnormalities come and go, and an ECG might not find them. You might be asked to wear a 24-hour Holter monitor to record your heart's electrical activity as you go about your daily routine.
Echocardiogram. This noninvasive exam, which includes an ultrasound of your chest, shows detailed images of your heart's structure and function.
Ultrasound waves are transmitted, and their echoes are recorded with a device called a transducer, which is held outside your body. A computer uses the information from the transducer to create moving images on a video monitor.
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 walk on a treadmill or do some other form of exercise. You might 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 may be monitored.
Tilt table test. If you have low blood pressure on standing, or from faulty brain signals (neurally mediated hypotension), a tilt table test can evaluate how your body reacts to changes in position.
During the test, you lie on a table that's tilted to raise the upper part of your body, which simulates the movement from horizontal to a standing position.
Source: http://www.mayoclinic.com
Even moderate forms of low blood pressure can cause dizziness, weakness, fainting and a risk of injury from falls.
And severely low blood pressure can deprive your body of enough oxygen to carry out its normal functions, leading to damage to your heart and brain.
Source: http://www.mayoclinic.com
Depending on the reason for your low blood pressure, you might be able to reduce or prevent symptoms.
Eat a healthy diet. Get all the nutrients you need for good health by focusing on a variety of foods, including whole grains, fruits, vegetables, and lean chicken and fish.
If your doctor suggests using more salt but you don't like a lot of salt on your food, try using natural soy sauce or adding dry soup mixes to dips and dressings.
Pay attention to your body positions. Gently move from a prone or squatting to a standing position. Don't sit with your legs crossed.
Before arising in the morning, breathe deeply for a few minutes and then slowly sit up before standing. Sleeping with the head of your bed slightly elevated also can help fight the effects of gravity.
If you begin to get symptoms while standing, cross your thighs in a scissors fashion and squeeze, or put one foot on a ledge or chair and lean as far forward as possible. These maneuvers encourage blood flow from your legs to your heart.
Eat small, low-carb meals. To help prevent blood pressure from dropping sharply after meals, eat small portions several times a day and limit high-carbohydrate foods such as potatoes, rice, pasta and bread.
Your doctor also might recommend drinking caffeinated coffee or tea with meals to temporarily raise blood pressure. But because caffeine can cause other problems, check with your doctor before drinking more caffeinated beverages.
Source: http://www.mayoclinic.com
Low blood pressure (hypotension) can occur in anyone, though certain types of low blood pressure are more common depending on your age or other factors:
Source: http://www.mayoclinic.com
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