What Is Hypotension?
Hypotension (HI-po-TEN-shun) is low blood pressure.
Blood pressure is the force of blood pushing against the walls of the arteries
as the heart pumps out blood.
Blood pressure is measured as systolic (sis-TOL-ik)
and diastolic (di-a-STOL-ik) pressures. Systolic blood pressure is the pressure
when the heart beats while pumping blood. Diastolic blood pressure is the
pressure when the heart is at rest between beats.
You will most often see blood pressure numbers
written with the systolic number above or before the diastolic, such as 120/80
mmHg. (The mmHg is millimeters of mercurythe units used to measure blood
pressure.)
Normal blood pressure in adults is lower than 120/80
mmHg. Hypotension is blood pressure thats lower than 90/60 mmHg.
Overview
Blood pressure changes during the day. It lowers as
you sleep and rises when you wake up. It also can rise when youre
excited, nervous, or active.
Your body is very sensitive to changes in blood
pressure. Special cells in the arteries can sense if your blood pressure begins
to rise or fall. When this happens, the cells trigger your body to try to bring
blood pressure back to normal.
For example, if you stand up quickly, your blood
pressure may drop. The cells will sense the drop and will quickly take action
to make sure that blood continues to flow to your brain, kidneys, and other
important organs.
Most forms of hypotension happen because your body
cant bring blood pressure back to normal or cant do it fast
enough.
Some people have low blood pressure all of the time.
They have no signs or symptoms, and their low blood pressure is normal for
them. In other people, certain conditions or factors cause blood pressure to
drop below normal.
Hypotension is a medical concern only if it causes
signs or symptoms, such as dizziness, fainting, or, in extreme cases,
shock.
Outlook
In a healthy person, low blood pressure without
signs or symptoms usually isnt a problem and needs no treatment. If low
blood pressure causes signs or symptoms, your doctor will try to find and treat
the underlying condition thats causing it.
Hypotension can be dangerous. It can make a person
fall because of dizziness or fainting. Shock, a severe form of hypotension, is
a condition thats often fatal if not treated right away. With prompt and
proper treatment, shock can be successfully treated.
Types of Hypotension
There are several types of hypotension. People who
always have low blood pressure have chronic asymptomatic hypotension. They have
no signs or symptoms and need no treatment. Their low blood pressure is normal
for them.
Other types of hypotension occur only sometimes,
when blood pressure suddenly drops too low. The symptoms and effects on the
body range from mild to severe.
The three main types of this kind of hypotension are
orthostatic (OR-tho-STAT-ik) hypotension, neurally mediated hypotension (NMH),
and severe hypotension linked to
shock.
Orthostatic Hypotension
This type of low blood pressure occurs when standing
up from a sitting or lying down position. It can make you feel dizzy or
lightheaded, or even make you faint.
Orthostatic hypotension occurs if your body isn't
able to adjust blood pressure and blood flow fast enough for the change in
position. This type of low blood pressure usually lasts for only a few seconds
or minutes after you stand up. You may need to sit or lie down for a short time
while your blood pressure returns to normal.
Orthostatic hypotension can occur in all age groups.
However, it's more common in older adults, especially those who are frail or in
poor health. It can be a symptom of other medical conditions, and treatment
often focuses on treating the underlying condition(s).
Some people have orthostatic hypotension, but also
have high
blood pressure when lying down.
A form of orthostatic hypotension called
postprandial hypotension is a sudden drop in blood pressure after a meal. This
type of low blood pressure mostly affects older adults. It’s also more
likely to affect people who have high blood pressure or a central nervous
system disorder, such as Parkinson’s disease.
Neurally Mediated Hypotension
With NMH, blood pressure drops after youve
been standing for a long time. You may feel dizzy, faint, or sick to the
stomach as a result. This type of low blood pressure also can occur if you have
an unpleasant, upsetting, or scary experience.
NMH affects children and young adults more often
than people in other age groups. Children often outgrow NMH.
Severe Hypotension Linked to Shock
People may say a person has “gone into
shock” as a result of an upsetting event. But to doctors, the word
“shock” has a different meaning.
Shock is a life-threatening condition in which blood
pressure drops so low that the brain, kidneys, and other vital organs can't get
enough blood to work properly. Blood pressure drops much lower in shock than in
other types of hypotension.
Many factors can cause shock, such as major blood
loss, certain severe infections, severe burns and allergic reactions, and
poisoning. Shock can be fatal if its not treated right away.
Other Names for Hypotension
- Low blood pressure
- Neurally mediated hypotension
- Neurogenic orthostatic hypotension
- Orthostatic hypotension
- Postprandial hypotension
- Postural hypotension
- Shock
What Causes Hypotension?
Factors or conditions that disrupt the body’s
ability to control blood pressure cause hypotension. The different types of
hypotension have different causes.
Orthostatic Hypotension
Orthostatic hypotension has many causes. Sometimes
two or more factors combine to cause this type of low blood pressure.
Dehydration (de-hi-DRA-shun) is the most common
cause of orthostatic hypotension. Dehydration occurs when the body loses more
water than it takes in. You may become dehydrated if you don’t drink
enough fluids or if you sweat a lot during physical activity. Fever, vomiting,
and severe diarrhea also can lead to dehydration.
Orthostatic hypotension may occur during pregnancy,
but it generally goes away after the birth.
Because an older body doesn’t manage changes
in blood pressure as well as a younger body, getting older also can lead to
this type of hypotension.
Postprandial hypotension (a type of orthostatic
hypotension) mostly affects older adults. Postprandial hypotension is a sudden
drop in blood pressure after a meal.
Certain medical conditions can raise your risk for
orthostatic hypotension, including:
- Heart conditions, such as
heart
attack,
heart
valve disease,
bradycardia
(a very low heart rate), and
heart
failure. These conditions prevent the heart from pumping enough blood to
the body.
- Anemia
(uh-NEE-me-eh).
- Severe infections.
- Endocrine conditions, such as thyroid disorders,
Addison’s disease, low blood sugar, and diabetes.
- Disorders of the central nervous system, such as
Parkinson’s disease.
- Pulmonary
embolism.
Some medicines used to treat
high
blood pressure and heart disease can raise your risk for orthostatic
hypotension. These medicines include:
- Diuretics, or “water pills”
- Calcium channel blockers
- Angiotensin-converting enzyme (ACE) inhibitors
- Angiotensin II receptor blockers
- Nitrates
- Beta blockers
Medicines used to treat conditions such as anxiety,
depression, erectile dysfunction, and central nervous system disorders (like
Parkinson’s disease) also can increase your risk for orthostatic
hypotension.
Other substances, when taken with high blood
pressure medicines, also can lead to orthostatic hypotension. These substances
include alcohol, barbiturates, and some prescription and over-the-counter
medicines.
Finally, other factors or conditions that can
trigger orthostatic hypotension include being out in the heat or being immobile
(not being able to move around very much) for a long time.
Neurally Mediated Hypotension
Neurally mediated hypotension (NMH) occurs when the
brain and heart don’t communicate with each other properly.
For example, when you stand for a long time, blood
begins to pool in your legs. This causes your blood pressure to drop. In NHM,
the body mistakenly tells the brain that blood pressure is high. In response,
the brain slows the heart rate. This makes blood pressure drop even more,
causing dizziness and other symptoms.
Severe Hypotension Linked to Shock
Many factors and conditions can cause severe
hypotension linked to
shock. Some of these factors also can cause orthostatic
hypotension. In shock, though, blood pressure drops very low and doesn’t
return to normal on its own.
Shock is an emergency and must be treated right
away. If a person has
signs
or symptoms of shock, someone should call 9–1–1 right away.
Certain severe infections can cause shock. This is
known as septic shock. It can occur when bacteria enter the bloodstream. The
bacteria release a toxin (a poison) that leads to a dangerous drop in blood
pressure.
A severe loss of blood or fluids from the body also
can cause shock. This is known as hypovolemic (HI-po-vo-LE-mik) shock.
Hypovolemic shock can happen as a result of:
- Major external bleeding (for example, from a
severe cut or injury)
- Major internal bleeding (for example, from a
ruptured blood vessel or injury that causes bleeding inside the body)
- Major loss of body fluids from severe burns
- Severe swelling of the pancreas (an organ that
produces enzymes and hormones, such as insulin)
- Severe diarrhea
- Severe kidney disease
- Overuse of diuretics
A major decrease in the hearts ability to pump
blood also can cause shock. This is known as cardiogenic (KAR-de-o-JEN-ik)
shock. Heart attack, pulmonary embolism, or arrhythmia (an irregular heartbeat)
can cause this type of shock.
A sudden and extreme widening of the arteries and
drop in blood pressure also can cause shock. This is known as vasodilatory
(VA-so-DI-la-tory) shock. It can occur due to:
- A severe head injury
- A reaction to certain medicines
- Liver failure
- Poisoning
- A severe allergic reaction (called anaphylactic
(AN-a-fi-LAK-tik) shock)
Who Is At Risk for Hypotension?
Hypotension can affect people of all ages. However,
people in certain age groups are more likely to have certain types of low blood
pressure.
Older adults are more likely to have orthostatic and
postprandial hypotension. Children and young adults are more likely to have
neurally mediated hypotension.
People who take certain medicines, such as
high
blood pressure medicines, are at higher risk for low blood pressure. People
who have central nervous system disorders (such as Parkinson’s disease)
or some heart conditions also are at higher risk for low blood pressure.
Other risk factors for hypotension include being
immobile (not being able to move around very much) for long periods and
pregnancy. Hypotension during pregnancy is normal and goes away after
birth.
What Are the Signs and Symptoms of
Hypotension?
Orthostatic Hypotension
The signs and symptoms of orthostatic hypotension
may happen within a few seconds or minutes of standing up after you’ve
been sitting or lying down. You may feel that you’re going to faint, or
you may actually faint. Signs and symptoms include:
- Dizziness or feeling lightheaded
- Blurry vision
- Confusion
- Weakness
- Nausea (feeling sick to your stomach)
These signs and symptoms go away if you sit or lie
down for a few minutes until your blood pressure adjusts to normal.
Neurally Mediated Hypotension
The signs and symptoms of neurally mediated
hypotension (NMH) are similar to those of orthostatic hypotension. They occur
after standing for a long time or in response to an unpleasant, upsetting, or
scary experience.
The drop in blood pressure with NMH doesnt
last long and often goes away after sitting down.
Severe Hypotension Linked to Shock
In
shock, not enough blood flows to the major organs, including
the brain.
The early signs and symptoms of reduced blood flow
to the brain include lightheadedness, sleepiness, and confusion. In the
earliest stages of shock, it may be hard to detect any signs or symptoms. In
older people, the first symptom may only be confusion.
Over time, as shock worsens, a person won’t be
able to sit up without passing out. If the shock continues, the person will
lose consciousness. Shock is often fatal if not treated right away.
Other signs and symptoms of shock vary, depending on
what’s causing the shock. When low blood volume (from major blood loss,
for example) or poor pumping action in the heart (from
heart
failure, for example) causes shock:
- The skin becomes cold and sweaty. It often looks
blue or pale. If pressed, the color returns to normal more slowly than usual. A
bluish network of lines appears under the skin.
- The pulse becomes weak and rapid.
- The person begins to breathe very quickly.
When extreme widening or stretching of blood vessels
(such as in septic shock) causes shock, a person feels warm and flushed at
first. Later, the skin becomes cold and clammy, and the person feels very
sleepy.
Shock is an emergency and must be treated right
away. If a person has signs or symptoms of shock, someone should call
911 right away.
How Is Hypotension Diagnosed?
Hypotension is diagnosed based on your medical
history, a physical exam, and results from tests. Your doctor will want to
know:
- The type of low blood pressure you have and how
severe it is
- Whether an underlying condition is causing the
low blood pressure
Specialists Involved
A primary care doctor or specialist may diagnose and
treat hypotension. The type of specialist most commonly involved is a
cardiologist (heart specialist).
Other specialists also may be involved, such as
surgeons, nephrologists (kidney specialists), neurologists (brain and nerve
specialists), or others.
Diagnostic Tests
When a person is in
shock, someone should call 9–1–1 right away
because emergency treatment is needed.
For other types of hypotension, your doctor may
order tests to find out how your blood pressure responds in certain situations.
The results will help your doctor understand why you’re fainting or
having other symptoms.
Blood Tests
During a
blood
test, a small amount of blood is taken from your body. It’s usually
drawn from a vein in your arm using a thin needle. The procedure is quick and
easy, although it may cause some short-term discomfort.
Blood tests can show whether
anemia
or low blood sugar is causing your hypotension.
EKG (Electrocardiogram)
An
EKG
is a simple test that detects and records the heart’s electrical
activity. It shows how fast the heart is beating and the heart’s rhythm
(steady or irregular). An EKG also shows the strength and timing of electrical
signals as they pass through each part of the heart.
Holter and Event Monitors
Holter
and event monitors are medical devices that record the heart's electrical
activity. These monitors are similar to an EKG. However, a standard EKG only
records the heartbeat for a few seconds. It won't detect heart rhythm problems
that don't occur during the test.
Holter and event monitors are small, portable
devices. You can wear one while you do your normal daily activities. This
allows the monitor to record your heart longer than an EKG can.
Echocardiography
Echocardiography
is a test that uses sound waves to create a moving picture of your heart. The
picture shows how well your heart is working and its size and shape.
There are several different types of
echocardiography, including a stress echocardiogram, or “stress
echo.” This test is done as part of a stress test (see below). A stress
echo usually is done to find out whether you have decreased blood flow to your
heart, a sign of
coronary
artery disease.
Stress Test
Some heart problems are easier to diagnose when your
heart is working hard and beating fast. During
stress
testing, you exercise (or are given medicine if you’re unable to
exercise) to make your heart work hard and beat fast while heart tests are
done.
These tests may include
nuclear
heart scanning, echocardiography, and magnetic resonance imaging (MRI) and
positron emission tomography (PET) scanning of the heart.
Valsalva Maneuver
This is a simple test of the part of your nervous
system that controls functions such as your heartbeat and the narrowing and
widening of your blood vessels. If something goes wrong with this part of the
nervous system, blood pressure problems may occur.
During this test you take a deep breath and then
force the air out through your lips. You will do this several times. Your heart
rate and blood pressure will be checked during the test.
Tilt Table Test
This test is used if you have fainting spells for no
known reason. For the test, you lie on a table that moves from a lying down to
an upright position. Your doctor checks your reaction to the change in
position.
Doctors use a tilt table test to diagnose
orthostatic hypotension and neurally mediated hypotension (NMH). People who
have NMH usually faint during this test. The test can help your doctor find any
underlying brain or nerve condition.
How Is Hypotension Treated?
Treatment depends on the type of hypotension you
have and how severe your signs and symptoms are. The goals of treatment are to
relieve signs and symptoms and manage any underlying condition(s) causing the
hypotension.
Your response to treatment depends on your age,
overall health, and strength. It also depends on how easily you can stop,
start, or change medicines.
In a healthy person, low blood pressure without
signs or symptoms usually needs no treatment.
If you have
signs
or symptoms of low blood pressure, you should sit or lie down right away.
Put your feet above the level of your heart. If your symptoms don’t go
away quickly, you should seek medical care right away.
Orthostatic Hypotension
There are a number of treatments for orthostatic
hypotension. If you have this type of low blood pressure, your doctor may
advise making lifestyle changes such as:
- Drinking plenty of fluids, like water
- Drinking little or no alcohol
- Standing up slowly
- Not crossing your legs while sitting
- Gradually sitting up for longer periods if
you’ve been immobile (not able to move around much) for a long time due
to a medical condition
- Eating small, low-carbohydrate meals if you have
postprandial hypotension (a form of orthostatic hypotension)
Talk to your doctor about using compression
stockings. These stockings apply pressure to your lower legs. They help move
blood throughout your body.
If medicine is causing your low blood pressure, your
doctor may change the medicine or adjust the dose you take.
Several medicines also are used to treat orthostatic
hypotension. These medicines, which raise blood pressure, include
fludrocortisone and midodrine.
Neurally Mediated Hypotension
If you have neurally mediated hypotension (NMH), you
may need to make lifestyle changes. These may include:
- Avoiding situations that trigger symptoms. For
example, don’t stand for long periods. Try to avoid unpleasant,
upsetting, or scary situations.
- Drinking plenty of fluids, like water.
- Increasing your salt intake (as your doctor
advises).
- Learning to recognize symptoms that occur before
fainting and taking action to raise blood pressure. For example, sitting down
and putting your head between your knees can help raise blood pressure.
If medicine is causing your low blood pressure, your
doctor may change the medicine or adjust the dose you take. He or she also may
prescribe a medicine to treat NMH.
Children who have NHM often outgrow it.
Treating Severe Hypotension Linked to Shock
Shock is a life-threatening emergency. People who have shock
usually need to be treated in a hospital or by emergency medical personnel. If
a person has signs or symptoms of shock, someone should call 9–1–1
right away.
The goals of treating shock are to:
- Restore blood flow to the organs as quickly as
possible to prevent organ damage
- Find and reverse the cause of shock
Special fluid or blood injected into the bloodstream
is often used to restore blood flow to the organs. Medicines can be used to
raise blood pressure or make the heartbeat stronger. Depending on the cause of
the shock, other treatments, such as antibiotics or surgery, may be
needed.
Living With Hypotension
Doctors often can successfully treat hypotension.
Many people who have the disorder live normal, healthy lives.
If you have low blood pressure, you can take steps
to prevent or limit symptoms, such as dizzy spells and fainting.
If you have orthostatic hypotension, get up slowly
after sitting or lying down. Eat small, low-carbohydrate meals if you have
postprandial hypotension (a form of orthostatic hypotension).
If you have neurally mediated hypotension,
don’t stand for long periods. Also, drink plenty of fluids and try to
avoid unpleasant or scary situations. Learn to recognize symptoms and take
action to raise your blood pressure. Children who have NMH often outgrow
it.
Other lifestyle changes also can help you control
low blood pressure. For more information, talk to your doctor and see
“How
Is Hypotension Treated?”
Ask your doctor about learning how to measure your
own blood pressure. This will help you find out what a normal blood pressure
reading is for you. Keeping a record of blood pressure readings done by health
professionals also can help you learn more about your blood pressure.
Severe hypotension linked to
shock is an emergency. Shock can cause death if it’s not
treated right away. If a person has
signs
or symptoms of shock, someone should call 9–1–1 right away.
Key Points
- Hypotension is low blood pressure. Blood pressure
is the force of blood pushing against the walls of the arteries as the heart
pumps out blood.
- Normal blood pressure in adults is lower than
120/80 mmHg. Hypotension is blood pressure that’s lower than 90/60
mmHg.
- Some people have low blood pressure all the time.
They have no signs or symptoms and their low readings are normal for them. In
other people, certain conditions or factors cause blood pressure to drop below
normal.
- In a healthy person, low blood pressure without
signs or symptoms usually isn’t a problem and needs no treatment.
- The three main types of hypotension that causes
signs and symptoms are orthostatic hypotension, neurally mediated hypotension
(NMH), and severe hypotension linked to
shock.
- Orthostatic hypotension is low blood pressure
that occurs after standing up from a sitting or lying down position. With NMH,
blood pressure drops after you’ve been standing for a long time or due to
severe emotional stress. Shock is a life-threatening condition in which blood
pressure drops so low that the brain, kidneys, and other vital organs
can’t get enough blood to work properly. Many factors can cause shock,
such as major blood loss, certain severe infections, severe burns and allergic
reactions, and poisoning. Shock can be fatal if not treated right away.
- Factors or conditions that disrupt the
body’s ability to control blood pressure cause hypotension. The different
types of hypotension have different causes.
- Hypotension can affect people of all ages. Older
adults are more likely to have orthostatic and postprandial hypotension.
Children and young adults are more likely to have NMH.
- The signs and symptoms of orthostatic hypotension
and NMH include dizziness or feeling lightheaded, blurry vision, confusion,
weakness, and nausea (feeling sick to your stomach). You may feel as though
you’re going to faint, or you may actually faint. Both of these types of
hypotension can be dangerous if a person falls because of the dizziness or
fainting.
- Signs and symptoms of shock include
lightheadedness, sleepiness, and confusion. Over time, if shock worsens, a
person won’t be able to sit up without passing out. If the shock
continues, the person can lose consciousness. Other signs and symptoms of shock
include cold and sweaty skin, a weak and rapid pulse, and rapid breathing. If a
person has signs or symptoms of shock, someone should call 9–1–1
right away.
- Hypotension is diagnosed based on your medical
history, a physical exam, and results from tests.
- Treatment depends on the type of hypotension you
have and how severe your signs and symptoms are. The goals of treatment are to
relieve signs and symptoms and manage any underlying condition causing the
hypotension. Treatments may include lifestyle changes, compression stockings,
procedures, and medicines.
- Doctors often can successfully treat hypotension.
Many people who have the disorder live normal, healthy lives.
Links to Other Information About Hypotension
Non-NHLBI Resources
Clinical Trials
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