What is low blood pressure?
Blood pressure is the pressure of blood within the arteries of the body. Blood pressure is the
driving force that causes blood to flow through the body from the arteries (where the pressure is
high), through organs, and into the veins (where the pressure is low). Blood pressure is
generated by the pumping of blood by the heart into the arteries as well as by the resistance to
the flow of blood by the arteries. The systolic blood pressure (the top number) represents the
pressure in the arteries as the muscle of the heart contracts and pumps blood into the arteries.
The diastolic blood pressure (the bottom number) represents the pressure in the arteries as the
muscle of the heart relaxes after it contracts.
Systolic blood pressure for most healthy adults falls between 90 and 120 millimeters of mercury
(mm Hg). Normal diastolic blood pressure falls between 60 and 80 mm Hg. (By convention, an
individual’s blood pressure is written as systolic/diastolic blood pressure, e.g., 120/80). Current
guidelines define normal blood pressure as lower than 120/80. Blood pressures between 120/80
and 140/90, which used to be considered “pre-hypertension,” now are considered too high. High
blood pressure increases the risk of developing heart disease, kidney disease, hardening of the
arteries (atherosclerosis or arteriosclerosis), eye damage, and stroke.
Low blood pressure is blood pressure that is so low that it is causing symptoms or signs due to
the low flow of blood through the arteries and veins. When the flow of blood is too low to deliver
enough oxygen and nutrients to vital organs such as the brain, heart, and kidney; the organs do
not function normally and may be permanently damaged. It should be noted that unlike high blood
pressure, which is defined on the basis of blood pressure alone, low blood pressure is defined
primarily by signs and symptoms of low blood flow. In fact, some individuals may have a blood
pressure of 90/50 and have no signs or symptoms of low blood pressure, and, therefore, not have
low blood pressure while others who normally have a blood pressure of 130/80 may develop
symptoms and signs of low blood pressure if their blood pressure drops to 100/60.
How is blood pressure generated?
During relaxation of the heart (diastole) the left ventricle of the heart fills with blood returning from
the lungs. The left ventricle then contracts and pumps blood into the arteries (systole). The blood
pressure during contraction of the ventricle (systolic pressure) when blood is being actively
ejected into the arteries is higher than during relaxation of the ventricle (diastolic pressure). The
pulse that we can feel is caused by the contraction of the left ventricle. (Please read the How the
Heart Works article for more.)
Blood pressure is determined by two factors: 1) The amount of blood pumped by the left ventricle
of the heart into the arteries, and 2) the resistance to the flow of blood caused by the walls of the
arterioles (smaller arteries).
Generally, blood pressure tends to be higher if more blood is pumped into the arteries or if the
arterioles are narrow and stiff. (Narrow and stiff arterioles, by resisting the flow of blood, increase
blood pressure.)
Blood pressure tends to be lower if less blood is being pumped into the arteries or if the arterioles
are wider and more flexible and resisting the flow of blood less.
Thus, if arteries are narrowed and stiff, for example, from atherosclerosis, blood pressure must
increase to maintain the flow of blood. On the other hand, if arteries are wider and flexible, a
lesser blood pressure can maintain the flow of blood at a normal level.
How does the body maintain normal blood pressure?
The body has mechanisms to alter or maintain blood pressure and the flow of blood. There are
sensors in the walls of the arteries and heart that sense blood pressure. These sensors are called
baroreceptors. Baroreceptors sense blood pressure and then send signals to the heart, the
arterioles, the veins, and the kidneys that cause them to make changes that lower or increase
blood pressure. There are several ways in which blood pressure can be adjusted--by
adjusting the amount of blood pumped by the heart into the arteries (cardiac output), the amount
of blood contained in the veins, the arteriolar resistance, and the volume of blood.

The heart can speed up and contract more frequently, and it can eject more blood
with each contraction. Both of these responses increase the flow of blood into the
arteries and increase blood pressure.

The veins can expand and narrow. When veins expand, more blood can be stored in
the veins and less blood returns to the heart for pumping into the arteries. As a result, the
heart pumps less blood, and blood pressure is lower. On the other hand, when veins
narrow, less blood is stored in the veins, more blood returns to the heart for pumping into
the arteries, and, therefore, the heart pumps more blood and blood pressure is higher.

The arterioles can expand and narrow. Expanded arterioles create less resistance to
the flow of blood and decrease blood pressure while narrowed arterioles create more
resistance and raise blood pressure.

The kidney can respond to changes in blood pressure by increasing or decreasing
the amount of urine that is produced. Urine is primarily water that is removed from the
blood so that when the kidney makes more urine, the amount (volume) of blood that fills
the arteries and veins decreases, and this lowers blood pressure. If the kidneys make
less urine, the amount of blood that fills the arteries and veins increases and this
increases blood pressure. Compared with the other mechanisms for adjusting blood
pressure, changes in the production of urine affect blood pressure slowly over hours and
days. (The other mechanisms are effective in seconds.)
For example, low blood volume due to bleeding into the intestine can cause low blood pressure.
The body quickly responds to the low blood volume and pressure by the following adjustments
which all increase blood pressure:
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The heart rate increases and the forcefulness of the heart’s contractions increase, thus
more blood is pumped through the heart.
Veins narrow to return more blood to the heart for pumping.
Blood flow to the kidneys decrease to reduce the formation of urine, and increase the
volume of blood in the arteries and veins.
Arterioles narrow to increase resistance to blood flow
These adaptive responses will keep the blood pressure in the normal range unless blood loss
becomes so severe and protracted that the responses are overwhelmed.
Is low blood pressure bad for your health?
People who have lower blood pressures have a lower risk of strokes, kidney disease, and heart
diseases. Athletes, people who exercise regularly, people who maintain ideal body weights, and
non-smokers, tend to have lower blood pressures. Therefore, low blood pressure is desirable as
long as it is not low enough to cause symptoms and damage to organs in the body.
What are low blood pressure signs and symptoms?
When the blood pressure is not sufficient to deliver enough blood to the organs of the body, the
organs do not work properly and may be permanently damaged. For example, if insufficient blood
flows to the brain, brain cells do not receive enough oxygen and nutrients, and a person can feel
light-headed, dizzy, or even faint. Going from a sitting or lying position to a standing position often
brings out the symptoms of low blood pressure. This occurs because standing causes blood to
“settle” in the veins of the lower body, and this can lower the blood pressure. If the blood pressure
is already low, standing can make the low pressure worse to the point of causing symptoms. (The
development of light-headedness, dizziness, or fainting upon standing caused by low blood
pressure is called orthostatic hypotension. Normal individuals are able to compensate rapidly for
the low pressure created by standing with the responses discussed previously and do not
develop orthostatic hypotension.)
When there is insufficient blood pressure to deliver blood to the coronary arteries (the arteries
that supply blood to the heart’s muscle), a person can develop chest pain (angina) or even a
heart attack. When insufficient blood is delivered to the kidneys, the kidneys fail to eliminate
wastes from the body, for example, urea and creatinine, and an increase in their levels in the
blood occur (e.g., elevations of blood urea nitrogen or BUN and serum creatinine, respectively).
Shock is a life-threatening condition where persistently low blood pressure causes organs such
as kidney, liver, heart, lung, and brain to fail rapidly.
What are the causes of low blood pressure?
Conditions that reduce the volume of blood, reduce cardiac output (the amount of blood pumped
by the heart), and medications are frequent causes of low blood pressure.
Causes of low blood pressure due to low blood volume

Dehydration is common among patients with diarrhea who lose large amounts of water
in their stool, particularly when drowsiness limits their drinking of fluids or is associated
with nausea and vomiting. Dehydration also can occur with prolonged vomiting of any
cause because of the loss of water in the vomitus. Other causes of dehydration include
exercise, sweating, fever, and heat exhaustion or heat stroke. Individuals with mild
dehydration may experience only thirst and dry mouth. Moderate to severe dehydration
may cause orthostatic hypotension (manifest by light-headedness, dizziness or fainting
upon standing). Protracted and severe dehydration can lead to shock, kidney failure,
confusion, acidosis (too much acid in the blood), coma, and even death. For more,
please read the Dehydration article.

Moderate or severe bleeding can quickly deplete an individual’s body of blood, leading
to low blood pressure or orthostatic hypotension. Bleeding can result from trauma,
surgical complications, or from gastrointestinal abnormalities such as ulcers, tumors, or
diverticulosis. Occasionally, the bleeding may be so severe and rapid (for example,
bleeding from a ruptured aortic aneurysm) that it causes shock rapidly.

Severe inflammation of organs inside the body such as acute pancreatitis can cause
low blood pressure. In acute pancreatitis, fluid leaves the blood to enter the inflamed
tissues around the pancreas as well as the abdominal cavity, depleting the volume of
blood.
Causes of low blood pressure due to heart disease

Weakened heart muscle can cause the heart to fail and reduce the amount of blood it
pumps. One common cause of weakened heart muscle is the death of a large portion of
the heart’s muscle due to a single, large heart attack or repeated smaller heart attacks
(please read the Heart Attack article for more). Other examples of conditions that can
weaken the heart include medications that are toxic to the heart, infections of the muscle
of the heart by viruses (myocarditis), and diseases of the heart’s valves such as aortic
stenosis.

Pericarditis is an inflammation of the pericardium (the sac surrounding the heart).
Pericarditis can cause fluid to accumulate within the pericardium and around the heart,
restricting the ability of the heart to pump blood.

Pulmonary embolism is a condition in which a blood clot in a vein (a condition called
deep vein thrombosis) breaks off and travels to the heart and eventually the lung. A large
blood clot can block the flow of blood into the left ventricle from the lungs and severely
diminish the ability of the heart to pump blood. Pulmonary embolism is a life-threatening
emergency. For more, please read the Deep Vein Thrombosis and Pulmonary Embolism
article.

A slow heart rate (bradycardia) can decrease the amount of blood pumped by the
heart. The resting heart rate for a healthy adult is between 60 and 100 beats/minute.
Bradycardia (resting heart rates slower than 60 beats/minute) does not always cause low
blood pressure. In fact, some highly trained athletes can have resting heart rates in the
40’s and 50’s without any symptoms. (The slow heart rates are offset by more forceful
contractions of the heart that pump more blood than in non-athletes.) But in many
patients bradycardia can lead to low blood pressure, light-headedness, dizziness, and
even fainting.
One example of bradycardia, sick sinus syndrome, occurs common in the elderly. This syndrome
is due to degeneration of the sinus node (SA node), an area in the heart that generates electrical
signals that cause the heart to beat regularly. In the sick sinus syndrome, the diseased SA node
cannot generate signals fast enough to maintain a normal heart rate. Another condition that
causes bradycardia is heart block. Electrical signals from the SA node must travel to the rest of
the heart’s muscle to cause the heart to contract and pump blood. Normally these electrical
signals are transmitted along special tissues in the heart. Heart block occurs when these
specialized tissues are damaged by heart attacks, degeneration that occurs with aging, and
medications. Heart block prevents some or all of the electrical signals generated by the SA node
from reaching the rest of the heart, and this prevents the heart from contracting as rapidly as it
otherwise would.

An abnormally fast heart rate (tachycardia) also can cause low blood pressure. The
most common example of tachycardia causing low blood pressure is atrial fibrillation.
Atrial fibrillation is a disorder of the heart characterized by rapid and irregular electrical
discharges from the muscle of the heart (instead of the SA node), causing the ventricles
to contract irregularly and (usually) rapidly. The rapidly contracting ventricles do not have
enough time to fill maximally with blood before the each contraction, and the amount of
blood that is pumped decreases, in spite of the faster heart rate. Other abnormally rapid
heart rhythms such as ventricular tachycardia also can produce low blood pressure,
sometimes even life-threatening shock. For more, please read the Atrial Fibrillation
article.
Medications that cause low blood pressure

Medications such as calcium channel blockers, beta blockers, and digoxin (Lanoxin) can
slow the rate at which the heart contracts. Some elderly people are extremely sensitive to
these medications since they are more likely to have diseased SA nodes and electrical
conduction tissues. In some individuals, the heart rate can become dangerously slow
even with small doses of these medications.

Medications used in treating high blood pressure (such as ACE inhibitors, angiotensin
receptor blockers, beta-blockers, calcium channel blockers, and alpha-blockers) can
excessively lower blood pressure and result in symptomatic low blood pressure
especially among the elderly.

Diuretics (water pills) such as furosemide (Lasix) can decrease blood volume by causing
excessive urination.

Medications used for treating depression, such as amitriptyline (Elavil), Parkinson’s
disease, such as levodopa-carbidopa (Sinemet), erectile dysfunction (impotence), such
as sildenafil (Viagra) when used in combination with nitroglycerine, can cause low blood
pressure

Alcohol and narcotics also can cause low blood pressure.
Other condition s that cause low blood pressure

Vasovagal reaction is a common condition in which a healthy person temporarily
develops low blood pressure, slow heart rate, and sometimes fainting. A vasovagal
reaction typically is brought on by emotions of fear or pain such as having blood drawn or
starting an intravenous infusion. Vasovagal reactions are caused by the involuntary
(autonomic) nervous system releasing hormones that slow the heart and widen the blood
vessels.

Postural (orthostatic) hypotension, as discussed previously, is a sudden drop in blood
pressure when an individual stands up from a sitting, squatting, or supine (lying) position.
When a person stands up, gravity causes blood to settle in the veins in the legs, hence
less blood reaches the heart for pumping, and, as a result, the blood pressure drops. The
body normally responds automatically to the drop in blood pressure by increasing the rate
at which the heart beats and by narrowing the veins to return more blood to the heart. In
patients with postural hypotension, this compensating reflex fails to occur, resulting in
symptomatic low blood pressure. Postural hypotension can occur in persons of all ages
but is much more common among the elderly, especially in those on medications for high
blood pressure and/or diuretics. Other causes of postural hypotension include
dehydration, adrenal insufficiency (discussed shortly), prolonged bed rest, diabetes that
has caused damage to the autonomic nerves, alcoholism with damage to the autonomic
nerves, and certain rare neurological syndromes (e.g., Shy-Drager syndrome) that
damage the autonomic nerves.

Another form of postural hypotension occurs typically in young healthy
individuals. After prolonged standing, the individual’s heart rate and blood pressure
drops, causing dizziness, nausea and often fainting. In these individuals, the autonomic
nervous system wrongly responds to prolonged standing by directing the heart to slow
down and the veins to dilate.

Micturition syncope is a temporary drop in blood pressure and loss of consciousness
brought about by urinating. This condition typically occurs in elderly patients and may be
due to the release by the autonomic nerves of hormones that lower blood pressure.

Adrenal insufficiency, for example, due to Addison’s disease, can cause low blood
pressure. Addison’s disease is a disorder in which the adrenal glands (small glands next
to the kidneys) are destroyed. The destroyed adrenal glands can no longer produce
sufficient adrenal hormones (specifically cortisol) necessary for to maintain normal bodily
functions. Cortisol has many functions, one of which is to maintain blood pressure and
the function of the heart. Addison’s disease is characterized by loss of weight, muscle
weakness, fatigue, low blood pressure, and, sometimes, darkening of the skin.

Septicemia is a severe infection in which bacteria (or other infectious organisms such as
fungi) enter the blood. The infection typically originates in the lungs (as pneumonia),
bladder, or in the abdomen due to diverticulitis or gallstones. The bacteria then enter the
blood where they release toxins and cause life-threatening and profound low blood
pressure (septic shock), often with damage to several organs.

Anaphylaxis (anaphylactic shock) is a potentially fatal allergic reaction to medications
such as penicillin, intravenous iodine used in some x-ray studies, foods such as peanuts,
or bee stings. In addition to a profound drop in blood pressure, individuals may also
experience hives, wheezing, and a swollen throat with difficulty breathing.
How is low blood pressure diagnosed and evaluated?
In some individuals, particularly relatively healthy ones, symptoms of weakness, dizziness, and
fainting raise the suspicion of low blood pressure. In others, an event often associated with low
blood pressure, for example, a heart attack, has occurred to cause the symptoms. Measuring
blood pressure, sometimes in both the lying (supine) and standing positions usually is the first
step in diagnosing low blood pressure. In patients with symptomatic low blood pressure, there
often is a marked drop in blood pressure upon standing, and patients may even develop
orthostatic symptoms. Once low blood pressure has been identified as the cause of symptoms,
the goal is to identify the cause of the low blood pressure. Sometimes the causes are readily
apparent (such as loss of blood due to trauma, or sudden shock after receiving x-ray dyes
containing iodine). At other times, the cause may be identified by testing:

CBC (complete blood count). CBC may reveal anemia from blood loss or elevated
white blood cells due to infection.

Blood electrolyte measurements may show dehydration and mineral depletion, renal
failure, or acidosis (excess acid in the blood).

Cortisol levels can be measured to diagnose adrenal insufficiency and Addison’s
disease.

Blood and urine cultures can be performed to diagnose septicemia and bladder
infections, respectively.

Radiology studies, such as chest x-rays, abdominal ultrasounds and computerized
tomography (CT or CAT) scans may detect pneumonia, heart failure, gallstones,
pancreatitis, and diverticulitis.

Electrocardiograms (EKG) can detect abnormally slow or rapid heart beats, pericarditis,
and heart muscle damage from either old heart attacks or a reduced supply of blood to
the heart muscle that has not yet caused a heart attack.

Holter monitor recordings are used to diagnose intermittent episodes of abnormal heart
rhythms. If abnormal rhythms occur intermittently, a standard EKG performed at the time
of a visit to the doctor's office may not show the abnormal rhythm. A Holter monitor is a
continuous recording of the heart's rhythm for 24 hours that often is used to diagnose
intermittent episodes of bradycardia or tachycardia.

Patient-activated event recorder. If the episodes of bradycardia or tachycardia are
infrequent, a 24-hour Holter recording may not capture these sporadic episodes. In this
situation, a patient can wear a patient-activated event recorder for up to four weeks. The
patient presses a button to start the recording when he or she senses the onset of an
abnormal heart rhythm or symptoms possibly caused by hypotension. The doctor then
analyzes the recordings at a later date to identify the abnormal episodes.

Echocardiograms are examinations of the structures and motion of the heart using
ultrasound. Echocardiograms can detect pericardial fluid due to pericarditis, the extent of
heart muscle damage from heart attacks, diseases of the heart valves, and rare tumors of
the heart.

Ultrasound examinations of the leg veins and CT scans of the chest can detect deep
vein thrombosis and pulmonary embolism.

Tilt-table tests are used to evaluate patients suspected of having postural hypotension
or syncope due to abnormal autonomic nerves. During a tilt-table test, the patient lies on
an examining table with an intravenous infusion running while the heart rate and blood
pressure are monitored. The table then is tilted upright for 15 minutes to 45 minutes.
Heart rate and blood pressure are monitored every few minutes. The purpose of the test
is to try to reproduce postural hypotension. Sometimes a doctor may administer Isuprel
intravenously to induce postural hypotension. For more, please read our Tilt-table Test
procedure article.
How is low blood pressure diagnosed and evaluated?
In some individuals, particularly relatively healthy ones, symptoms of weakness, dizziness, and
fainting raise the suspicion of low blood pressure. In others, an event often associated with low
blood pressure, for example, a heart attack, has occurred to cause the symptoms. Measuring
blood pressure, sometimes in both the lying (supine) and standing positions usually is the first
step in diagnosing low blood pressure. In patients with symptomatic low blood pressure, there
often is a marked drop in blood pressure upon standing, and patients may even develop
orthostatic symptoms. Once low blood pressure has been identified as the cause of symptoms,
the goal is to identify the cause of the low blood pressure. Sometimes the causes are readily
apparent (such as loss of blood due to trauma, or sudden shock after receiving x-ray dyes
containing iodine). At other times, the cause may be identified by testing:

CBC (complete blood count). CBC may reveal anemia from blood loss or elevated
white blood cells due to infection.

Blood electrolyte measurements may show dehydration and mineral depletion, renal
failure, or acidosis (excess acid in the blood).

Cortisol levels can be measured to diagnose adrenal insufficiency and Addison’s
disease.

Blood and urine cultures can be performed to diagnose septicemia and bladder
infections, respectively.

Radiology studies, such as chest x-rays, abdominal ultrasounds and computerized
tomography (CT or CAT) scans may detect pneumonia, heart failure, gallstones,
pancreatitis, and diverticulitis.

Electrocardiograms (EKG) can detect abnormally slow or rapid heart beats, pericarditis,
and heart muscle damage from either old heart attacks or a reduced supply of blood to
the heart muscle that has not yet caused a heart attack.

Holter monitor recordings are used to diagnose intermittent episodes of abnormal heart
rhythms. If abnormal rhythms occur intermittently, a standard EKG performed at the time
of a visit to the doctor's office may not show the abnormal rhythm. A Holter monitor is a
continuous recording of the heart's rhythm for 24 hours that often is used to diagnose
intermittent episodes of bradycardia or tachycardia.

Patient-activated event recorder. If the episodes of bradycardia or tachycardia are
infrequent, a 24-hour Holter recording may not capture these sporadic episodes. In this
situation, a patient can wear a patient-activated event recorder for up to four weeks. The
patient presses a button to start the recording when he or she senses the onset of an
abnormal heart rhythm or symptoms possibly caused by hypotension. The doctor then
analyzes the recordings at a later date to identify the abnormal episodes.

Echocardiograms are examinations of the structures and motion of the heart using
ultrasound. Echocardiograms can detect pericardial fluid due to pericarditis, the extent of
heart muscle damage from heart attacks, diseases of the heart valves, and rare tumors of
the heart.

Ultrasound examinations of the leg veins and CT scans of the chest can detect deep
vein thrombosis and pulmonary embolism.

Tilt-table tests are used to evaluate patients suspected of having postural hypotension
or syncope due to abnormal autonomic nerves. During a tilt-table test, the patient lies on
an examining table with an intravenous infusion running while the heart rate and blood
pressure are monitored. The table then is tilted upright for 15 minutes to 45 minutes.
Heart rate and blood pressure are monitored every few minutes. The purpose of the test
is to try to reproduce postural hypotension. Sometimes a doctor may administer Isuprel
intravenously to induce postural hypotension. For more, please read our Tilt-table Test
procedure article.
How is low blood pressure diagnosed and evaluated?
In some individuals, particularly relatively healthy ones, symptoms of weakness, dizziness, and
fainting raise the suspicion of low blood pressure. In others, an event often associated with low
blood pressure, for example, a heart attack, has occurred to cause the symptoms. Measuring
blood pressure, sometimes in both the lying (supine) and standing positions usually is the first
step in diagnosing low blood pressure. In patients with symptomatic low blood pressure, there
often is a marked drop in blood pressure upon standing, and patients may even develop
orthostatic symptoms. Once low blood pressure has been identified as the cause of symptoms,
the goal is to identify the cause of the low blood pressure. Sometimes the causes are readily
apparent (such as loss of blood due to trauma, or sudden shock after receiving x-ray dyes
containing iodine). At other times, the cause may be identified by testing:

CBC (complete blood count). CBC may reveal anemia from blood loss or elevated
white blood cells due to infection.

Blood electrolyte measurements may show dehydration and mineral depletion, renal
failure, or acidosis (excess acid in the blood).

Cortisol levels can be measured to diagnose adrenal insufficiency and Addison’s
disease.

Blood and urine cultures can be performed to diagnose septicemia and bladder
infections, respectively.

Radiology studies, such as chest x-rays, abdominal ultrasounds and computerized
tomography (CT or CAT) scans may detect pneumonia, heart failure, gallstones,
pancreatitis, and diverticulitis.

Electrocardiograms (EKG) can detect abnormally slow or rapid heart beats, pericarditis,
and heart muscle damage from either old heart attacks or a reduced supply of blood to
the heart muscle that has not yet caused a heart attack.

Holter monitor recordings are used to diagnose intermittent episodes of abnormal heart
rhythms. If abnormal rhythms occur intermittently, a standard EKG performed at the time
of a visit to the doctor's office may not show the abnormal rhythm. A Holter monitor is a
continuous recording of the heart's rhythm for 24 hours that often is used to diagnose
intermittent episodes of bradycardia or tachycardia.

Patient-activated event recorder. If the episodes of bradycardia or tachycardia are
infrequent, a 24-hour Holter recording may not capture these sporadic episodes. In this
situation, a patient can wear a patient-activated event recorder for up to four weeks. The
patient presses a button to start the recording when he or she senses the onset of an
abnormal heart rhythm or symptoms possibly caused by hypotension. The doctor then
analyzes the recordings at a later date to identify the abnormal episodes.

Echocardiograms are examinations of the structures and motion of the heart using
ultrasound. Echocardiograms can detect pericardial fluid due to pericarditis, the extent of
heart muscle damage from heart attacks, diseases of the heart valves, and rare tumors of
the heart.

Ultrasound examinations of the leg veins and CT scans of the chest can detect deep
vein thrombosis and pulmonary embolism.

Tilt-table tests are used to evaluate patients suspected of having postural hypotension
or syncope due to abnormal autonomic nerves. During a tilt-table test, the patient lies on
an examining table with an intravenous infusion running while the heart rate and blood
pressure are monitored. The table then is tilted upright for 15 minutes to 45 minutes.
Heart rate and blood pressure are monitored every few minutes. The purpose of the test
is to try to reproduce postural hypotension. Sometimes a doctor may administer Isuprel
intravenously to induce postural hypotension. For more, please read our Tilt-table Test
procedure article.
How is low blood pressure treated?
Low blood pressure in healthy subjects without symptoms or organ damage needs no treatment.
All patients with symptoms possibly due to low blood pressure should be evaluated by a doctor.
(Patients who have had a major drop in blood pressure from their usual levels even without the
development of symptoms also should be evaluated.) The doctor needs to identify the cause of
the low blood pressure since treatment will depend on the cause. For example, if a medication is
causing the low blood pressure, the dose of medication may have to be reduced or the
medication stopped, though only after consulting the doctor. Self-adjustment of medication
should not be done.

Dehydration is treated with fluids and minerals (electrolytes). Mild dehydration without
nausea and vomiting can be treated with oral fluids and electrolytes. Moderate to severe
dehydration usually is treated in the hospital or emergency room with intravenous fluids
and electrolytes.

Blood loss can be treated with intravenous fluids and blood transfusions. If bleeding is
continuing, it needs to be treated as well.

Septicemia is treated with intravenous fluids and antibiotics.

Blood pressure medications or diuretics are adjusted, changed, or stopped by the
doctor if they are causing low blood pressure symptoms.

Bradycardia may be due to a medication. The doctor may reduce, change or stop the
medication. Bradycardia due to sick sinus syndrome or heart block is treated with an
implantable pacemaker.

Tachycardia is treated depending on the nature of the tachycardia. Atrial fibrillation can
be treated with oral medications, electrical cardioversion, or a catheterization procedure
called pulmonary vein isolation. Ventricular tachycardia can be controlled with
medications or with an implantable defibrillator.

Pulmonary embolism and deep vein thrombosis is treated with blood thinners,
intravenous heparin initially and oral warfarin later.

Pericardial fluid can be removed by a procedure called pericardiocentesis.

Postural hypotension can be treated by increasing water and salt intake, using
compression stockings to compress the leg veins and reduce the pooling of blood in the
veins, and, in some patients, the use of a medication called proamatine (Midodrine). The
problem with proamatine is that while it increases blood pressure in the upright position,
the supine blood pressure may become too high, thus increasing the risk of strokes.
Mayo clinic researchers found that a medication used to treat muscle weakness in
Myasthenia gravis called pyridostigmine (Mestinon) increases upright blood pressure but
not supine blood pressure. Mestinon is an anticholinesterase medication that works on
the autonomic nervous system, especially when a person is standing up. Side effects of
pyridostigmine include minor abdominal cramping or increased frequency of bowel
movements. Increasing salt intake can lead to heart failure in patients with existing heart
disease and should not be undertaken without consulting a doctor.
Low Blood Pressure At A Glance

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

Low blood pressure, also called hypotension, is blood pressure that is low enough that
the flow of blood to the organs of the body is inadequate and symptoms and/or signs of
low blood flow develop.
Low pressure alone, without symptoms or signs, usually is not unhealthy.
The symptoms of low blood pressure include light-headedness, dizziness, and fainting.
These symptoms are most prominent when individuals go from the lying or sitting position
to the standing position (orthostatic hypotension).
Low blood pressure that causes an inadequate flow of blood to the body’s organs can
cause strokes, heart attacks, and failure of the kidneys.
Common causes of low blood pressure include a reduced volume of blood, heart
disease, and medications.
Low blood pressure is suspected on the basis of the symptoms it produces and can be
confirmed by measuring blood pressure (unless the symptoms are intermittent).
The cause of low blood pressure can be determined with blood tests, radiologic studies,
and cardiac testing to look for arrhythmias.
Treatment of low blood pressure is determined by the cause of the low pressure.