Is low blood pressure?
Blood pressure is the force exerted by circulating blood on the walls of blood vessels, and is one of the principal vital signs of life, which also include heart rate, respiratory rate, and temperature. Blood pressure produced by the heart pumps blood into the arteries and regulated by the response by the arteries to blood flow.
An individual's blood pressure is expressed as systolic / diastolic blood pressure, for example, 120/80.The systolic blood pressure (top number) is the pressure in the arteries as the heart muscle to contract and pump blood into it. Diastolic blood pressure (bottom number) is the pressure in the arteries as the heart muscle to relax after a contract. Blood pressure is always higher when the heart is pumping (squeezing) than when relaxed.
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. current guidelines define normal blood pressure as lower than 120/80. blood pressure higher than 130/80 is considered 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 (hypotension) is pressure so low cause symptoms or signs due to low blood flow through arteries and veins. When blood flow is too low to provide enough oxygen and nutrients to vital organs such as brain, heart, and kidneys, the organs are not functioning normally and may be permanently damaged.
Unlike high blood pressure, low blood pressure is defined primarily by signs and symptoms of low blood flow and not by the number of certain blood pressure. Some individuals may have a blood pressure of 90/50 with no symptoms of low blood pressure and therefore does not have low blood pressure. However, others who normally have high blood pressure may develop symptoms of low blood pressure if their blood pressure dropped to 100/60.
How is blood pressure generated?
During cardiac relaxation (diastole) the heart's left ventricle fills with blood returning from the lungs. The left ventricle then contracts and pumps blood into the arteries (systole). Blood pressure during the contraction pressure (ventricular systolic) when blood is being actively released into the artery is higher than the pressure relaxation (diastolic ventricular). The pulse can we feel when we put our fingers on the artery caused by contraction of the left ventricle.
Blood pressure is determined by two factors: 1) The amount of blood pumped by the heart's left ventricle into the artery, and 2) resistance to blood flow caused by the walls of the arterioles (smaller arteries).
In general, blood pressure tends to be higher if more blood is pumped into the artery or if the arterioles are narrow and stiff. (Narrow and rigid arterioles, by rejecting the bloodstream, increasing blood pressure.) This often occurs when older patients develop atherosclerosis.
Blood pressure tends to be lower if less blood is being pumped into the artery or if the arterioles are larger and more flexible and, therefore, has less resistance to blood flow.
How does the body maintain normal blood pressure?
The body has mechanisms to alter or maintain blood pressure and blood flow. There is a blood pressure sensor in the sense of the arterial wall and send signals to the heart, arterioles, blood vessels, and kidneys that cause them to make changes that lower or raise 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 blood vessels, arteriolar resistance, and blood volume.
* The heart can speed up and contract more frequently and can eject more blood with each contraction. Both of these responses increase blood flow to the arteries and increase blood pressure.
The veins can expand and narrow. When the blood vessels expand, more blood can be stored in the veins and less blood returning to the heart to pump into the artery. As a result, the heart pumps less blood, and blood pressure is lower.
* Arteriole can expand and narrow. creates less resistance arterioles expanded blood flow and decreased blood pressure, whereas arteriolar narrowing creates more resistance and raise blood pressure.
* The kidneys can respond to changes in blood pressure by increasing or decreasing the amount of urine produced. Urine is primarily water released from the blood. When the kidneys make more urine, the amount (volume) of blood that fills the arteries and decreases, and this lowers blood pressure. If the kidneys make less urine, the amount of blood that fills the arteries and increase blood pressure and this increase. Compared with other mechanisms to regulate blood pressure, changes in the production of urine affect blood pressure slowly over hours and days. (The other mechanism is effective in a matter of seconds.)
For example, low blood volume due to bleeding (such as bleeding ulcers in your stomach or from a bad wound from injury) can cause low blood pressure. The body responds quickly to low blood volume and pressure by the following adjustments which all increase blood pressure:
- Increased heart rate and exemplary a strong contraction of the heart increases, so that more blood is pumped through the heart.
- Narrow veins to return more blood to the heart to pump.
- Blood flow to the kidney decreased to reduce the formation of urine and thus increase the volume of blood in the arteries and veins.
- Narrower arterioles to increased resistance to blood flow
Adaptation of this response will keep the blood pressure within normal limits except blood loss becomes so severe that response is overwhelmed
Is low blood pressure bad for your health?
People who have low blood pressure have a lower risk of stroke, kidney disease, and heart disease. Athletes, people who exercise regularly, people who maintain ideal body weight, and non-smokers tend to have low blood pressure. Therefore, low blood pressure is desirable as long as it is not low enough to cause symptoms and damage organs in the body.
What are the signs and symptoms of low blood pressure?
When blood pressure is not sufficient to provide enough blood to organs, organs are not working properly and can be permanently damaged. For example, if blood flow to the brain is inadequate, brain cells do not receive enough oxygen and nutrients, and the person may feel dizzy, dizzy, or even fainting.
Going from sitting or lying position to a standing position often brings out symptoms of low blood pressure. This occurs because standing causes blood to "settle" in the vein of the lower body, and this can lower blood pressure. If blood pressure is already low, standing can make the low pressure worse, to the point of causing symptoms. Development of light, dizziness, or fainting after standing due to low blood pressure is called orthostatic hypotension. normal individuals can rapidly compensate for the low pressure created by standing with the responses discussed previously and do not develop orthostatic hypotension.
If there is not enough blood pressure to deliver blood to the coronary arteries (arteries that supply blood to the heart muscle), one can experience chest pain (symptoms of angina) or even a heart attack.
When insufficient blood sent to the kidneys, kidney failure to eliminate impurities from the body, for example, urea and creatinine, and increase their levels in the blood occurs (eg, increased blood urea nitrogen or BUN and serum creatinine, respectively).
Shock is a life-threatening condition in which persistent low blood pressure causes organs such as kidneys, liver, heart, lungs, and brain to fail rapidly.
What are the causes of low blood pressure?
Condition that reduces blood volume, reduced cardiac output (amount of blood pumped by the heart), and drugs that often cause low blood pressure.
Dehydration is common among patients with prolonged nausea, vomiting, and diarrhea. A large amount of water lost when vomiting and diarrhea, especially if the patient does not drink a sufficient amount of fluids to replace water discharged.
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 (spoken by the light, dizziness, or fainting when standing). Protracted and severe dehydration can cause shock, kidney failure, confusion, acidosis (too much acid in the blood), coma and even death.
Moderate or severe bleeding can quickly spend the blood of a person's body, causing low blood pressure or orthostatic hypotension. Bleeding can result from trauma, surgical complications, or from gastrointestinal disorders such as ulcers, tumors, or diverticulosis. Sometimes, bleeding may be very severe and rapid (eg, bleeding from ruptured aortic aneurysm), causing shock and rapid death.
Severe inflammation of organs in the body such as acute pancreatitis can cause low blood pressure. In acute pancreatitis, fluid leaves the blood vessels to enter the inflamed tissue around the pancreas and abdominal cavity, depleting the blood volume.
Causes of low blood pressure due to heart disease
weakened heart muscle can cause heart failure and reduce the amount of blood it pumps. One common cause of heart muscle is weak is the death of most of the heart muscle caused by the attack, the heart of a large single or repeated smaller heart attacks. Other examples of conditions that can weaken the heart include medications that are toxic to the heart, the heart muscle infection by viruses (myocarditis), and heart valve disease such as aortic stenosis.
Pericarditis is inflammation of the pericardium (sac around the heart). Pericarditis can cause fluid to collect in the pericardium and compress the heart, restricting the ability of the heart to fill and pump blood.
Pulmonary embolism is a condition in which blood clots in the veins (deep vein thrombosis) breaks off and travel to the heart and lungs eventually. A large blood clot can block blood flow to the left ventricle from the lungs and greatly reduces the blood back to the heart to pump. Pulmonary embolism is a life-threatening emergency.
A slow heart rate (bradycardia) can decrease the amount of blood pumped by the heart. Heart rate for healthy adults is between 60 and 100 beats / minute. Bradycardia (resting heart rate is slower than 60 beats / minute) does not always lead to low blood pressure. In fact, some highly trained athletes can have resting heart rates in the 40s and 50s (beats per minute) without symptoms. (Slow heart rate, offset by a stronger contraction of the heart that pumps more blood than non-athletes), but. In many patients bradycardia can cause low blood pressure, lightheadedness, dizziness and even fainting.
Some common reasons for bradycardia include: 1) sick sinus syndrome, 2) heart block, and 3) drug toxicity. Many of these conditions occur in the elderly.
sick sinus syndrome: Sick sinus syndrome occurs when the heart's electrical system can not generate signals fast enough to maintain a normal heart rhythm.
Heart block: Heart block occurs when a particular network that sends electric currents in the heart damaged by heart attacks, degeneration of atherosclerosis, and drugs. Heart block prevents some or all of the electrical signals from reaching the remaining liver, and this prevents the heart from the contract as quickly as would otherwise be.
Drug poisoning: Drugs such as digoxin (Lanoxin) or beta blockers for high blood pressure, may slow the transmission of electricity in the heart of chemical and can cause bradycardia and hypotension (see below "Treatment that causes low blood pressure").
An abnormally rapid heartbeat (tachycardia) also can cause low blood pressure. The most common examples of tachycardia causing low blood pressure is atrial fibrillation. Atrial fibrillation is a cardiac disorder characterized by an electric discharge from the rapid and irregular heart muscle causing the ventricles to contract irregularly and (usually) quickly. Rapidly contracting ventricles do not have enough time to fill maximally with blood before each contraction, and the amount of blood pumped though heart rate decreased more rapidly. Other abnormal heart rhythms such as ventricular tachycardia fast can also result in low blood pressure, sometimes even life-threatening shock.
Drugs that cause low blood pressure
Drugs such as calcium channel blockers, beta blockers, and digoxin (Lanoxin) can slow the rate at which the heart contracts. Some parents are very sensitive to these drugs because they are more likely to have a diseased heart and electrical conduction tissue. In some individuals, slow heart rate can be dangerous even with small doses of the drug.
Medications used in treating high blood pressure (such as ACE inhibitors, angiotensin receptor blockers, beta blockers, calcium channel blockers, and alpha-blockers) may be too low blood pressure and cause the symptoms of low blood pressure especially among the elderly.
Water pills (diuretics) such as furosemide (Lasix) can decrease blood volume by causing excessive urination.
Medications used to treat depression, such as amitriptyline (Elavil), Parkinson's disease, such as levodopa-carbidopa (Sinemet), erectile dysfunction (impotence), such as sildenafil (Viagra), vardenafil (Levitra) and tadalafil (Cialis) when used in combination with nitroglycerin, can cause low blood pressure.
Alcohol and narcotics also can cause low blood pressure.
Other conditions that cause low blood pressure
Vasovagal reaction is a common condition in which healthy people while developing low blood pressure, slow heartbeat, and sometimes fainting. Vasovagal reaction is usually brought on by emotions such as fear or pain of blood after being taken, starting intravenous infusions, or with gastrointestinal upset. Vasovagal reactions are caused by voluntary activity (autonomic) nervous system, particularly the vagus nerve, which secretes hormones that slow the heart and dilate blood vessels. The vagus nerve controls the heart rate (slowing down). The vagus nerve also controls the functions of the digestive tract and senses activity in the digestive system. Thus, some people can have a vasovagal reaction from businesses in the bowel movement or vomiting.
Postural (orthostatic) hypotension is a decrease in blood pressure suddenly when a person stands up from sitting, squatting, or supine (lying down) position. When a person stands, gravity causes blood to settle in blood vessels in the legs, so that less blood reaches the heart to pump, and as a result of reduced blood pressure. The body usually responds automatically to a decrease in blood pressure by increasing the rate at which the heart rhythm and constriction of blood vessels to return more blood to the heart. In patients with postural hypotension, this compensating reflex fails to occur, resulting in symptoms of low blood pressure. Postural hypotension can occur in people of all ages but is much more common among older people, particularly those on medications for high blood pressure and / or diuretics. Other causes include postural hypotension, dehydration, adrenal insufficiency (discussed later), a long break, diabetes causes damage to the autonomic nerve, autonomic nerve damage with alcoholism, and some rare neurological syndromes (eg, Shy-Drager syndrome), which damage the autonomic nerves.
Another form of postural hypotension usually occurs in young healthy people. After long standing, heart rate and individual drops of blood pressure, cause dizziness, nausea, and fainting spells. In these people, one of the autonomic nervous system response to long standing by directing the heart to slow and blood vessels to dilate.
micturition syncope is a temporary reduction in blood pressure and loss of consciousness due to urination. This condition usually occurs in elderly patients and may be due to the release by the autonomic nervous hormone that lowers blood pressure.
adrenal insufficiency, for example, because of Addison's disease, can cause low blood pressure. Addison's disease is a disorder where the adrenal glands (small glands next to the kidney) are destroyed. Adrenal glands were destroyed can no longer produce enough adrenal hormones (specifically cortisol) are necessary to maintain normal body function. Cortisol has many functions, one of which is to maintain blood pressure and heart function. Addison's disease is characterized by weight loss, 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. Infection usually originates from 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 blood pressure and low depth (septic shock), often with damage to several organs.
-Anaphylaxis (anaphylactic shock) is a fatal allergic reaction to drugs such as penicillin, intravenous iodine are used in some x-ray studies, foods such as peanuts, or bee stings (insect stings). In addition to weight reduction on blood pressure, individuals may also experience itching, wheezing, and throat swelling with difficulty breathing. shock is caused by enlarged blood vessels that contain blood and release of water from the blood into the tissues.
How is low blood pressure diagnosed and evaluated?
In some individuals, particularly a relatively healthy, the symptoms of weakness, dizziness, fainting and low blood pressure increases suspicion. In others, the events are often associated with low blood pressure, such as heart attack has occurred causing the symptoms.
Measuring blood pressure, sometimes both in lying on his back () and the standing position is usually the first step in diagnosing low blood pressure. In patients with symptoms of low blood pressure, often marked decrease in blood pressure on standing, and patients may experience orthostatic symptoms. Heart rate increased very often. Having low blood pressure has been identified as the cause of symptoms, the goal is to identify the causes of low blood pressure. Sometimes the cause may be immediately obvious (such as blood loss due to trauma, or sudden shock after receiving x-ray dyes that contain iodine). At other times, the cause can be identified by testing:
-CBC (complete blood count). CBC may show anemia due to blood loss or a high white blood cells because of infection.
-Blood electrolyte measurements can indicate dehydration and mineral depletion, renal failure (kidney 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 be performed to diagnose a bladder infection and septicemia, respectively.
-Radiological studies, such as chest x-ray, abdominal ultrasound, and computerized tomography (CT or CAT) scan can detect pneumonia, heart failure, gallstones, pancreatitis, and diverticulitis.
-Electrocardiograms (EKG) can detect abnormal heart beats slow or fast, pericarditis, and heart muscle damage either from a previous heart attack or Reduced blood supply to the heart muscle that do not cause heart attacks.
-Holter monitor recordings are used to diagnose the occasional episodes of abnormal heart rhythms. If the abnormal rhythm occurs occasionally, a standard EKG done during a visit to the doctor's office may not show abnormal rhythm. A Holter monitor is a continuous recording of heart rhythm for 24 hours which is often used to diagnose the occasional episodes of bradycardia or tachycardia.
Treat-activated event recorder. If episodes of bradycardia or tachycardia is rare, 24-hour Holter recording may not capture these sporadic episodes. In this situation, patients can use the event-activated recorder for patients up to four weeks. The patient presses the button to start recording when she felt the start of the abnormal heart rhythm or symptoms may be caused by low blood pressure. The doctor then analyzes the tape at a later date to identify the abnormal episodes.
-Echocardiograms is the examination structure and movement of the heart using ultrasound. Echocardiograms can detect pericardial fluid due to pericarditis, the level of damage to heart muscle from heart attack, heart valve disease, and rare tumors of the heart.
-Ultrasound examination of venous leg and chest CT scans may detect deep venous thrombosis and pulmonary embolism.
-Tilt-table test is used to evaluate patients suspected of suffering from postural hypotension or syncope due to autonomic nervous abnormalities. During tilt-table test, patients lie on the examining table with an intravenous infusion administered while the heart rate and blood pressure are monitored. then the table is tilted upright for 15 minutes to 45 minutes. Heart rate and blood pressure were monitored every few minutes. The purpose of this test is to try to reproduce the postural hypotension. Sometimes doctors may manage epinephrine (Adrenalin, Isuprel) intravenously to induce postural hypotension.
How is low blood pressure treated?
Low blood pressure in healthy subjects without symptoms or organ damage needs no treatment. However, all patients with symptoms possibly due to low blood pressure should be evaluated by a physician. (Patients who have experienced a large drop in blood pressure than their normal levels even without the development of symptoms should also be evaluated.) Physicians need to identify the causes of low blood pressure because the treatment will depend on the cause. For example, if the treatment causes low blood pressure, drug dose may be reduced or the drug was stopped, though only after consulting a doctor. Adjustment of treatment 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 a hospital or emergency room with intravenous fluids and electrolytes.
- Blood loss can be treated with intravenous fluids and blood transfusions. Persistent and severe bleeding should be treated immediately.
- Septic shock is an emergency and treated with intravenous fluids and antibiotics.
- Blood pressure drugs or diuretics are adjusted, modified, or terminated by the doctor if they are causing symptoms of low blood pressure.
- Bradycardia may be due to treatment. Doctors can reduce, modify or discontinue treatment. Bradycardia due to sick sinus syndrome or heart block treated with a pacemaker implant.
- 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 medication or with an implanted defibrillator.
- Pulmonary embolism and deep venous thrombosis treated with blood thinners, initially with intravenous heparin and oral warfarin (Coumadin) later.
- Pericardial fluid can be removed with a procedure called perikardiosentesis.
- Postural hypotension can be treated by increasing water and salt * intake, increasing intake of caffeinated beverages because caffeine constricts blood vessels, using compression stockings to compress the leg veins and reduce the pooling of blood vessels in the legs, and in some patients, the use of a drug called midodrine (ProAmatine ). The problem with ProAmatine is that despite increasing blood pressure in an upright position, supine blood pressure may become too high, thus increasing the risk of stroke. Mayo Clinic researchers found that drugs used to treat muscle weakness in Myasthenia gravis is called pyridostigmine (Mestinon) increases blood pressure upright but not supine blood pressure. Mestinon, a drug anticholinesterase, works on the autonomic nervous system, especially when a person stands. Side effects include mild abdominal cramping or increased frequency of bowel movements. * Note: Increasing salt intake can cause heart failure in patients with existing heart disease and should not be undertaken without consulting a doctor.
- Postprandial hypotension refers to low blood pressure occurs after a meal. Ibuprofen (Motrin) or indomethacin (Indocin) may be beneficial.
Vasovagal syncope can be treated with several types of drugs such as beta blockers [eg, propranolol (Inderal, Inderal LA)], a selective inhibitor of serotonin Reuptake [fluoxetine (Prozac), escitalopram oxalate (Lexapro), paroxetine (Paxil), sertraline (Zoloft) , citalopram (Celexa), fluvoxamine (Luvox)], fludrocortisone (Florinef) (a drug that prevents dehydration by causing kidney (s) to retain water). A pacemaker can also help when a patient fails drug therapy.
Low Blood Pressure Overview
- Low blood pressure, also called hypotension, blood pressure is low enough so that blood flow to organs and symptoms of inadequate and / or signs of low blood flow develops.
- Low pressure, without symptoms or signs, are usually unhealthy.
- The symptoms of low blood pressure, including mild dizziness, and fainting. These symptoms are most pronounced when individuals move from lying or sitting position to standing position (orthostatic hypotension).
- Low blood pressure causes inadequate blood flow to the organs can cause strokes, heart attacks, and kidney failure. This is the most severe form is a shock.
- Common causes of low blood pressure include reduced blood volume, heart disease, and drugs.
- Causes of low blood pressure can be determined with blood tests, radiological studies, and cardiac testing to look for arrhythmias.
- Treatment of low blood pressure is determined by the cause of low pressure
References:
Medlineplus, "Vital Signs." WebMD, "Alpha blocker medications for prostatitis." Hilz MJ, Marthol H, Neundorfer B. "Syncope - a systematic overview of classification, pathogenesis, diagnosis and management," Fortschr Neurol Psychiatr. 2002 February; 70 (2) :95-107. Park Nicollet Methodist Hospital, "postural hypotension." American Family Physician, "Off-Label Applications for SSRIs."
Blood pressure is the force exerted by circulating blood on the walls of blood vessels, and is one of the principal vital signs of life, which also include heart rate, respiratory rate, and temperature. Blood pressure produced by the heart pumps blood into the arteries and regulated by the response by the arteries to blood flow.
An individual's blood pressure is expressed as systolic / diastolic blood pressure, for example, 120/80.The systolic blood pressure (top number) is the pressure in the arteries as the heart muscle to contract and pump blood into it. Diastolic blood pressure (bottom number) is the pressure in the arteries as the heart muscle to relax after a contract. Blood pressure is always higher when the heart is pumping (squeezing) than when relaxed.
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. current guidelines define normal blood pressure as lower than 120/80. blood pressure higher than 130/80 is considered 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 (hypotension) is pressure so low cause symptoms or signs due to low blood flow through arteries and veins. When blood flow is too low to provide enough oxygen and nutrients to vital organs such as brain, heart, and kidneys, the organs are not functioning normally and may be permanently damaged.
Unlike high blood pressure, low blood pressure is defined primarily by signs and symptoms of low blood flow and not by the number of certain blood pressure. Some individuals may have a blood pressure of 90/50 with no symptoms of low blood pressure and therefore does not have low blood pressure. However, others who normally have high blood pressure may develop symptoms of low blood pressure if their blood pressure dropped to 100/60.
How is blood pressure generated?
During cardiac relaxation (diastole) the heart's left ventricle fills with blood returning from the lungs. The left ventricle then contracts and pumps blood into the arteries (systole). Blood pressure during the contraction pressure (ventricular systolic) when blood is being actively released into the artery is higher than the pressure relaxation (diastolic ventricular). The pulse can we feel when we put our fingers on the artery caused by contraction of the left ventricle.
Blood pressure is determined by two factors: 1) The amount of blood pumped by the heart's left ventricle into the artery, and 2) resistance to blood flow caused by the walls of the arterioles (smaller arteries).
In general, blood pressure tends to be higher if more blood is pumped into the artery or if the arterioles are narrow and stiff. (Narrow and rigid arterioles, by rejecting the bloodstream, increasing blood pressure.) This often occurs when older patients develop atherosclerosis.
Blood pressure tends to be lower if less blood is being pumped into the artery or if the arterioles are larger and more flexible and, therefore, has less resistance to blood flow.
How does the body maintain normal blood pressure?
The body has mechanisms to alter or maintain blood pressure and blood flow. There is a blood pressure sensor in the sense of the arterial wall and send signals to the heart, arterioles, blood vessels, and kidneys that cause them to make changes that lower or raise 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 blood vessels, arteriolar resistance, and blood volume.
* The heart can speed up and contract more frequently and can eject more blood with each contraction. Both of these responses increase blood flow to the arteries and increase blood pressure.
The veins can expand and narrow. When the blood vessels expand, more blood can be stored in the veins and less blood returning to the heart to pump into the artery. As a result, the heart pumps less blood, and blood pressure is lower.
* Arteriole can expand and narrow. creates less resistance arterioles expanded blood flow and decreased blood pressure, whereas arteriolar narrowing creates more resistance and raise blood pressure.
* The kidneys can respond to changes in blood pressure by increasing or decreasing the amount of urine produced. Urine is primarily water released from the blood. When the kidneys make more urine, the amount (volume) of blood that fills the arteries and decreases, and this lowers blood pressure. If the kidneys make less urine, the amount of blood that fills the arteries and increase blood pressure and this increase. Compared with other mechanisms to regulate blood pressure, changes in the production of urine affect blood pressure slowly over hours and days. (The other mechanism is effective in a matter of seconds.)
For example, low blood volume due to bleeding (such as bleeding ulcers in your stomach or from a bad wound from injury) can cause low blood pressure. The body responds quickly to low blood volume and pressure by the following adjustments which all increase blood pressure:
- Increased heart rate and exemplary a strong contraction of the heart increases, so that more blood is pumped through the heart.
- Narrow veins to return more blood to the heart to pump.
- Blood flow to the kidney decreased to reduce the formation of urine and thus increase the volume of blood in the arteries and veins.
- Narrower arterioles to increased resistance to blood flow
Adaptation of this response will keep the blood pressure within normal limits except blood loss becomes so severe that response is overwhelmed
Is low blood pressure bad for your health?
People who have low blood pressure have a lower risk of stroke, kidney disease, and heart disease. Athletes, people who exercise regularly, people who maintain ideal body weight, and non-smokers tend to have low blood pressure. Therefore, low blood pressure is desirable as long as it is not low enough to cause symptoms and damage organs in the body.
What are the signs and symptoms of low blood pressure?
When blood pressure is not sufficient to provide enough blood to organs, organs are not working properly and can be permanently damaged. For example, if blood flow to the brain is inadequate, brain cells do not receive enough oxygen and nutrients, and the person may feel dizzy, dizzy, or even fainting.
Going from sitting or lying position to a standing position often brings out symptoms of low blood pressure. This occurs because standing causes blood to "settle" in the vein of the lower body, and this can lower blood pressure. If blood pressure is already low, standing can make the low pressure worse, to the point of causing symptoms. Development of light, dizziness, or fainting after standing due to low blood pressure is called orthostatic hypotension. normal individuals can rapidly compensate for the low pressure created by standing with the responses discussed previously and do not develop orthostatic hypotension.
If there is not enough blood pressure to deliver blood to the coronary arteries (arteries that supply blood to the heart muscle), one can experience chest pain (symptoms of angina) or even a heart attack.
When insufficient blood sent to the kidneys, kidney failure to eliminate impurities from the body, for example, urea and creatinine, and increase their levels in the blood occurs (eg, increased blood urea nitrogen or BUN and serum creatinine, respectively).
Shock is a life-threatening condition in which persistent low blood pressure causes organs such as kidneys, liver, heart, lungs, and brain to fail rapidly.
What are the causes of low blood pressure?
Condition that reduces blood volume, reduced cardiac output (amount of blood pumped by the heart), and drugs that often cause low blood pressure.
Dehydration is common among patients with prolonged nausea, vomiting, and diarrhea. A large amount of water lost when vomiting and diarrhea, especially if the patient does not drink a sufficient amount of fluids to replace water discharged.
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 (spoken by the light, dizziness, or fainting when standing). Protracted and severe dehydration can cause shock, kidney failure, confusion, acidosis (too much acid in the blood), coma and even death.
Moderate or severe bleeding can quickly spend the blood of a person's body, causing low blood pressure or orthostatic hypotension. Bleeding can result from trauma, surgical complications, or from gastrointestinal disorders such as ulcers, tumors, or diverticulosis. Sometimes, bleeding may be very severe and rapid (eg, bleeding from ruptured aortic aneurysm), causing shock and rapid death.
Severe inflammation of organs in the body such as acute pancreatitis can cause low blood pressure. In acute pancreatitis, fluid leaves the blood vessels to enter the inflamed tissue around the pancreas and abdominal cavity, depleting the blood volume.
Causes of low blood pressure due to heart disease
weakened heart muscle can cause heart failure and reduce the amount of blood it pumps. One common cause of heart muscle is weak is the death of most of the heart muscle caused by the attack, the heart of a large single or repeated smaller heart attacks. Other examples of conditions that can weaken the heart include medications that are toxic to the heart, the heart muscle infection by viruses (myocarditis), and heart valve disease such as aortic stenosis.
Pericarditis is inflammation of the pericardium (sac around the heart). Pericarditis can cause fluid to collect in the pericardium and compress the heart, restricting the ability of the heart to fill and pump blood.
Pulmonary embolism is a condition in which blood clots in the veins (deep vein thrombosis) breaks off and travel to the heart and lungs eventually. A large blood clot can block blood flow to the left ventricle from the lungs and greatly reduces the blood back to the heart to pump. Pulmonary embolism is a life-threatening emergency.
A slow heart rate (bradycardia) can decrease the amount of blood pumped by the heart. Heart rate for healthy adults is between 60 and 100 beats / minute. Bradycardia (resting heart rate is slower than 60 beats / minute) does not always lead to low blood pressure. In fact, some highly trained athletes can have resting heart rates in the 40s and 50s (beats per minute) without symptoms. (Slow heart rate, offset by a stronger contraction of the heart that pumps more blood than non-athletes), but. In many patients bradycardia can cause low blood pressure, lightheadedness, dizziness and even fainting.
Some common reasons for bradycardia include: 1) sick sinus syndrome, 2) heart block, and 3) drug toxicity. Many of these conditions occur in the elderly.
sick sinus syndrome: Sick sinus syndrome occurs when the heart's electrical system can not generate signals fast enough to maintain a normal heart rhythm.
Heart block: Heart block occurs when a particular network that sends electric currents in the heart damaged by heart attacks, degeneration of atherosclerosis, and drugs. Heart block prevents some or all of the electrical signals from reaching the remaining liver, and this prevents the heart from the contract as quickly as would otherwise be.
Drug poisoning: Drugs such as digoxin (Lanoxin) or beta blockers for high blood pressure, may slow the transmission of electricity in the heart of chemical and can cause bradycardia and hypotension (see below "Treatment that causes low blood pressure").
An abnormally rapid heartbeat (tachycardia) also can cause low blood pressure. The most common examples of tachycardia causing low blood pressure is atrial fibrillation. Atrial fibrillation is a cardiac disorder characterized by an electric discharge from the rapid and irregular heart muscle causing the ventricles to contract irregularly and (usually) quickly. Rapidly contracting ventricles do not have enough time to fill maximally with blood before each contraction, and the amount of blood pumped though heart rate decreased more rapidly. Other abnormal heart rhythms such as ventricular tachycardia fast can also result in low blood pressure, sometimes even life-threatening shock.
Drugs that cause low blood pressure
Drugs such as calcium channel blockers, beta blockers, and digoxin (Lanoxin) can slow the rate at which the heart contracts. Some parents are very sensitive to these drugs because they are more likely to have a diseased heart and electrical conduction tissue. In some individuals, slow heart rate can be dangerous even with small doses of the drug.
Medications used in treating high blood pressure (such as ACE inhibitors, angiotensin receptor blockers, beta blockers, calcium channel blockers, and alpha-blockers) may be too low blood pressure and cause the symptoms of low blood pressure especially among the elderly.
Water pills (diuretics) such as furosemide (Lasix) can decrease blood volume by causing excessive urination.
Medications used to treat depression, such as amitriptyline (Elavil), Parkinson's disease, such as levodopa-carbidopa (Sinemet), erectile dysfunction (impotence), such as sildenafil (Viagra), vardenafil (Levitra) and tadalafil (Cialis) when used in combination with nitroglycerin, can cause low blood pressure.
Alcohol and narcotics also can cause low blood pressure.
Other conditions that cause low blood pressure
Vasovagal reaction is a common condition in which healthy people while developing low blood pressure, slow heartbeat, and sometimes fainting. Vasovagal reaction is usually brought on by emotions such as fear or pain of blood after being taken, starting intravenous infusions, or with gastrointestinal upset. Vasovagal reactions are caused by voluntary activity (autonomic) nervous system, particularly the vagus nerve, which secretes hormones that slow the heart and dilate blood vessels. The vagus nerve controls the heart rate (slowing down). The vagus nerve also controls the functions of the digestive tract and senses activity in the digestive system. Thus, some people can have a vasovagal reaction from businesses in the bowel movement or vomiting.
Postural (orthostatic) hypotension is a decrease in blood pressure suddenly when a person stands up from sitting, squatting, or supine (lying down) position. When a person stands, gravity causes blood to settle in blood vessels in the legs, so that less blood reaches the heart to pump, and as a result of reduced blood pressure. The body usually responds automatically to a decrease in blood pressure by increasing the rate at which the heart rhythm and constriction of blood vessels to return more blood to the heart. In patients with postural hypotension, this compensating reflex fails to occur, resulting in symptoms of low blood pressure. Postural hypotension can occur in people of all ages but is much more common among older people, particularly those on medications for high blood pressure and / or diuretics. Other causes include postural hypotension, dehydration, adrenal insufficiency (discussed later), a long break, diabetes causes damage to the autonomic nerve, autonomic nerve damage with alcoholism, and some rare neurological syndromes (eg, Shy-Drager syndrome), which damage the autonomic nerves.
Another form of postural hypotension usually occurs in young healthy people. After long standing, heart rate and individual drops of blood pressure, cause dizziness, nausea, and fainting spells. In these people, one of the autonomic nervous system response to long standing by directing the heart to slow and blood vessels to dilate.
micturition syncope is a temporary reduction in blood pressure and loss of consciousness due to urination. This condition usually occurs in elderly patients and may be due to the release by the autonomic nervous hormone that lowers blood pressure.
adrenal insufficiency, for example, because of Addison's disease, can cause low blood pressure. Addison's disease is a disorder where the adrenal glands (small glands next to the kidney) are destroyed. Adrenal glands were destroyed can no longer produce enough adrenal hormones (specifically cortisol) are necessary to maintain normal body function. Cortisol has many functions, one of which is to maintain blood pressure and heart function. Addison's disease is characterized by weight loss, 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. Infection usually originates from 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 blood pressure and low depth (septic shock), often with damage to several organs.
-Anaphylaxis (anaphylactic shock) is a fatal allergic reaction to drugs such as penicillin, intravenous iodine are used in some x-ray studies, foods such as peanuts, or bee stings (insect stings). In addition to weight reduction on blood pressure, individuals may also experience itching, wheezing, and throat swelling with difficulty breathing. shock is caused by enlarged blood vessels that contain blood and release of water from the blood into the tissues.
How is low blood pressure diagnosed and evaluated?
In some individuals, particularly a relatively healthy, the symptoms of weakness, dizziness, fainting and low blood pressure increases suspicion. In others, the events are often associated with low blood pressure, such as heart attack has occurred causing the symptoms.
Measuring blood pressure, sometimes both in lying on his back () and the standing position is usually the first step in diagnosing low blood pressure. In patients with symptoms of low blood pressure, often marked decrease in blood pressure on standing, and patients may experience orthostatic symptoms. Heart rate increased very often. Having low blood pressure has been identified as the cause of symptoms, the goal is to identify the causes of low blood pressure. Sometimes the cause may be immediately obvious (such as blood loss due to trauma, or sudden shock after receiving x-ray dyes that contain iodine). At other times, the cause can be identified by testing:
-CBC (complete blood count). CBC may show anemia due to blood loss or a high white blood cells because of infection.
-Blood electrolyte measurements can indicate dehydration and mineral depletion, renal failure (kidney 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 be performed to diagnose a bladder infection and septicemia, respectively.
-Radiological studies, such as chest x-ray, abdominal ultrasound, and computerized tomography (CT or CAT) scan can detect pneumonia, heart failure, gallstones, pancreatitis, and diverticulitis.
-Electrocardiograms (EKG) can detect abnormal heart beats slow or fast, pericarditis, and heart muscle damage either from a previous heart attack or Reduced blood supply to the heart muscle that do not cause heart attacks.
-Holter monitor recordings are used to diagnose the occasional episodes of abnormal heart rhythms. If the abnormal rhythm occurs occasionally, a standard EKG done during a visit to the doctor's office may not show abnormal rhythm. A Holter monitor is a continuous recording of heart rhythm for 24 hours which is often used to diagnose the occasional episodes of bradycardia or tachycardia.
Treat-activated event recorder. If episodes of bradycardia or tachycardia is rare, 24-hour Holter recording may not capture these sporadic episodes. In this situation, patients can use the event-activated recorder for patients up to four weeks. The patient presses the button to start recording when she felt the start of the abnormal heart rhythm or symptoms may be caused by low blood pressure. The doctor then analyzes the tape at a later date to identify the abnormal episodes.
-Echocardiograms is the examination structure and movement of the heart using ultrasound. Echocardiograms can detect pericardial fluid due to pericarditis, the level of damage to heart muscle from heart attack, heart valve disease, and rare tumors of the heart.
-Ultrasound examination of venous leg and chest CT scans may detect deep venous thrombosis and pulmonary embolism.
-Tilt-table test is used to evaluate patients suspected of suffering from postural hypotension or syncope due to autonomic nervous abnormalities. During tilt-table test, patients lie on the examining table with an intravenous infusion administered while the heart rate and blood pressure are monitored. then the table is tilted upright for 15 minutes to 45 minutes. Heart rate and blood pressure were monitored every few minutes. The purpose of this test is to try to reproduce the postural hypotension. Sometimes doctors may manage epinephrine (Adrenalin, Isuprel) intravenously to induce postural hypotension.
How is low blood pressure treated?
Low blood pressure in healthy subjects without symptoms or organ damage needs no treatment. However, all patients with symptoms possibly due to low blood pressure should be evaluated by a physician. (Patients who have experienced a large drop in blood pressure than their normal levels even without the development of symptoms should also be evaluated.) Physicians need to identify the causes of low blood pressure because the treatment will depend on the cause. For example, if the treatment causes low blood pressure, drug dose may be reduced or the drug was stopped, though only after consulting a doctor. Adjustment of treatment 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 a hospital or emergency room with intravenous fluids and electrolytes.
- Blood loss can be treated with intravenous fluids and blood transfusions. Persistent and severe bleeding should be treated immediately.
- Septic shock is an emergency and treated with intravenous fluids and antibiotics.
- Blood pressure drugs or diuretics are adjusted, modified, or terminated by the doctor if they are causing symptoms of low blood pressure.
- Bradycardia may be due to treatment. Doctors can reduce, modify or discontinue treatment. Bradycardia due to sick sinus syndrome or heart block treated with a pacemaker implant.
- 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 medication or with an implanted defibrillator.
- Pulmonary embolism and deep venous thrombosis treated with blood thinners, initially with intravenous heparin and oral warfarin (Coumadin) later.
- Pericardial fluid can be removed with a procedure called perikardiosentesis.
- Postural hypotension can be treated by increasing water and salt * intake, increasing intake of caffeinated beverages because caffeine constricts blood vessels, using compression stockings to compress the leg veins and reduce the pooling of blood vessels in the legs, and in some patients, the use of a drug called midodrine (ProAmatine ). The problem with ProAmatine is that despite increasing blood pressure in an upright position, supine blood pressure may become too high, thus increasing the risk of stroke. Mayo Clinic researchers found that drugs used to treat muscle weakness in Myasthenia gravis is called pyridostigmine (Mestinon) increases blood pressure upright but not supine blood pressure. Mestinon, a drug anticholinesterase, works on the autonomic nervous system, especially when a person stands. Side effects include mild abdominal cramping or increased frequency of bowel movements. * Note: Increasing salt intake can cause heart failure in patients with existing heart disease and should not be undertaken without consulting a doctor.
- Postprandial hypotension refers to low blood pressure occurs after a meal. Ibuprofen (Motrin) or indomethacin (Indocin) may be beneficial.
Vasovagal syncope can be treated with several types of drugs such as beta blockers [eg, propranolol (Inderal, Inderal LA)], a selective inhibitor of serotonin Reuptake [fluoxetine (Prozac), escitalopram oxalate (Lexapro), paroxetine (Paxil), sertraline (Zoloft) , citalopram (Celexa), fluvoxamine (Luvox)], fludrocortisone (Florinef) (a drug that prevents dehydration by causing kidney (s) to retain water). A pacemaker can also help when a patient fails drug therapy.
Low Blood Pressure Overview
- Low blood pressure, also called hypotension, blood pressure is low enough so that blood flow to organs and symptoms of inadequate and / or signs of low blood flow develops.
- Low pressure, without symptoms or signs, are usually unhealthy.
- The symptoms of low blood pressure, including mild dizziness, and fainting. These symptoms are most pronounced when individuals move from lying or sitting position to standing position (orthostatic hypotension).
- Low blood pressure causes inadequate blood flow to the organs can cause strokes, heart attacks, and kidney failure. This is the most severe form is a shock.
- Common causes of low blood pressure include reduced blood volume, heart disease, and drugs.
- Causes of low blood pressure can be determined with blood tests, radiological studies, and cardiac testing to look for arrhythmias.
- Treatment of low blood pressure is determined by the cause of low pressure
References:
Medlineplus, "Vital Signs." WebMD, "Alpha blocker medications for prostatitis." Hilz MJ, Marthol H, Neundorfer B. "Syncope - a systematic overview of classification, pathogenesis, diagnosis and management," Fortschr Neurol Psychiatr. 2002 February; 70 (2) :95-107. Park Nicollet Methodist Hospital, "postural hypotension." American Family Physician, "Off-Label Applications for SSRIs."
0 komentar:
Post a Comment