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Low blood pressure

 

Low blood pressure is also called as hypotension in medical terms. Its value is less than 90/60 and normal blood pressure is in the range of 120/80 (systolic/diastolic).Low blood pressure can be abn underlying sign especially in elderly and it ma cause inadequate blood flow to the heart, brain and other vital organs.

Chronic low blood pressure in not serious but with some health problems occur when it drops.Because the brain is deprived of adequate blood supply leading to dizziness or lightheadedness.It acn be of many types as postural hypotension, orthostatic hypotension, or neurally mediated orthostatic hypotension.

Postural hypotension is a failure of the autonomic nervous system .The part of the nervous system controls the involuntary vital actions, such as the heartbeat to react appropriately to sudden changes. When you stand up, some blood pools in your lower extremities. This would cause your blood pressure to fall. Normally our body compensates by sending messages to your heart to beat faster and to your blood vessels to constrict. This offsets the drop in blood pressure. If this does not happen or happens too slowly, postural hypotension results.

Both low and high blood pressure normally increases with age. Blood flow in the brain declines with age as a result of plaque buildup in blood vessels. So the prevalence of postural hypotension also increases with age.10-20% of elderly people have postural hypotension.

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.

When there is insufficient blood pressure to deliver blood to the coronary arteries which are the arteries that supply blood to the heartís 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.

Causes

The cause of low blood pressure in not clear. Some of them are:
Pregnancy.
Hormonal problems such as an underactive thyroid (hypothyroidism), overactive thyroid (hyperthyroidism),diabetes, and low blood sugar (hypoglycemia).
Many medications.
Overdose of high blood pressure drugs.
Heart failure.
Heart arrhythmias (abnormal heart rhythms).
Widening or dilation of the blood vessels.
Heat exhaustion or heat stroke.
Liver disease.

Sudden drops in blood pressure can be life-threatening. Causes of this type of hypotension include:
Loss of blood (bleeding).
Low body temperature.
High body temperature.
Heart muscle disease causing heart failure.
Sepsis, a severe blood infection.
Severe dehydration.
A reaction to medication.
Severe allergic reaction (anaphylaxis).

Postural hypotension can attack anyone for various reasons such as dehydration, lack of food, prolonged standing in the heat, or being generally run down,by genetic make-up, aging, medication, dietary and psychological factors, and acute triggers such as infection and allergy.

Postural hypotension occurs most frequently in people who are taking drugs to control high blood pressure (hypertension). It can also be related to pregnancy, strong emotions, hardening of the arteries (atherosclerosis), or diabetes. The elderly are particularly affected especially those who have high blood pressure or autonomic nervous dysfunction.

There are drugs that are commonly associated with postural hypotension. These medications can be divided into two major categories
1) medications and
2) other common causes:

Drugs used to treat high blood pressure, such as diuretics, beta-blockers, calcium channel blockers, and angiotensin-converting enzyme (ACE) inhibiting drugs.
Drugs that have hypotension as a side effect, including nitrates, drugs for Parkinson's disease, antipsychotics, neuroleptics, anti-anxiety agents, sedative-hypnotics, and tricyclic antidepressants.

Common causes of naturally occurring postural hypotension include:
Dehydration and electrolyte loss, which may result from another condition, such as diarrhea or vomiting or excessive blood loss during female menstruation.
Age-associated decline in blood pressure regulation, which may be worsened by certain health conditions or medications.

Common causes of pathologic (attributable to a disease) postural hypotension include:
Central nervous system disorders, such as Shy-Drager syndrome. (multiple system neuropathy)
Peripheral neuropathy and autonomic neuropathy (nerve problems), such as may be caused by diabetes.
Cardiovascular disorders.
Alcoholism.
Nutritional diseases.

Diagnosis

In some individuals particularly 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.

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.They are:

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 Addisonís 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. 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.

Treatment

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 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.

 


 
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