Category Archives: Low Blood Pressure

What is Postprandial Hypotension

Postprandial hypotension is an abnormally low blood pressure which develops following a meal, often causing dizziness or even fainting.

  • Light-headedness, dizziness and fainting are the common symptoms.
  • Postprandial hypotension can be diagnosed by taking the blood pressure readings before a meal and after it.
  • Instead of a few large meals, eating several small meals with lower carbohydrate content, helps avoid postprandial hypotension.

Postprandial hypotension is prevalent among older people, occurring in about a third of them. People with high blood pressure are more prone to it. People, who have disorders of the autonomic nervous system which regulates blood pressure including Parkinson’s disease, and those who have diabetes or Shy-Drager syndrome, are also more likely to have this condition. Younger people are not found to have postprandial hypotension.

Causes

Soon after a meal, large quantities of blood flow to the stomach and intestines to aid in digestion and absorption of nutrients from the food. Normally, arterioles elsewhere in the body constrict, and the heart pumps more forcefully and more frequently, to maintain arterial pressure within normal range during digestion. But in some people, the compensatory mechanism of the body is not efficient enough to bring about the required changes, to maintain blood pressure within range. This results in postprandial hypotension.

Symptoms and Diagnosis

Light-headedness, giddiness and fainting soon after a meal, may be experienced by many older persons due to the development of postprandial hypotension. Measuring the blood pressure before and after eating a meal can confirm the diagnosis.

Treatment

Antihypertensive medication should not be taken before meals, by people with a tendency to develop postprandial hypotension.  Adjusting the dosage of the antihypertensive drugs may also help in avoiding hypotension. Several small meals low in carbohydrates should replace full meals. Also, people should lie down and rest for a while after every meal. A walk after meals may help some people to avoid a drop in the blood pressure, but when they stop walking, there is a higher risk of developing hypotension and falling down.

Coffee can be taken before meals especially before breakfast as caffeine has the effect of constricting blood vessels, but eventually its effectiveness may become less. NSAIDs or nonsteroidal anti-inflammatory drugs such as paracetamol and ibuprofen may help increase the volume of blood through salt retention. In severe cases of postprandial hypotension, the patient may be hospitalized and the drug octreotide which reduces blood flow to the intestine may be given as injections.

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What Is Orthostatic hypotension, Its Causes and Treatment

What is Orthostatic hypotension ? Orthostatic hypotension is a sudden lowering of blood pressure when a person quickly changes posture to an upright position, to either sit up or stand, resulting in lightheadedness or fainting, due to decreased flow of blood to the brain.

When a person suddenly changes position to sit up or stand, dizziness or fainting may occur.

  • Orthostatic hypotension may be diagnosed by measuring the blood pressure, when a person is sitting up or standing and again when he is lying down.
  • Drinking enough fluids and avoiding sudden movements while trying to sit up or stand may help, even when the condition is not curable.

Usually, older people develop orthostatic hypotension. When gravity has caused blood to accumulate in the lower parts of the body, it reduces the amount of blood available to the heart to pump out into the arteries, causing a drop in arterial pressure. Normally, the body immediately reacts to the fall in blood pressure, by raising the heart rate and the force of each contraction of the heart, as well as by constricting the arterioles to increase the blood pressure in the arteries. If the blood pressure controlling mechanism of the body is too slow to restore normal pressure when there is a sudden drop, probably due to ageing, orthostatic hypotension results.

Causes of Orthostatic hypotension

When the body’s blood pressure controlling mechanism is impaired due to certain disorders, or interrupted by drugs, or if it has slowed down due to ageing, it may result in orthostatic hypotension.

Certain heart disorders, such as abnormal arrhythmias, valve disorders and heart failure decrease the capacity of the heart, so that it cannot cope up with the sudden increase in demand, when the person sits up from a resting position, or the extra effort required for pumping blood against gravity. Ageing also impairs the heart’s ability to beat faster or more forcefully, when requirement arises from a sudden change in posture.

Diuretics taken by people with high blood pressure, to eliminate excess fluid from the body, can cause reduction in the volume of circulating blood and result in orthostatic hypotension. Fluid loss through severe diarrhea and vomiting, or heavy bleeding, can also result in orthostatic hypotension. People with conditions such as diabetes and Addison’s disease may lose a lot of fluid by frequent urination and copious sweating, which may make them dehydrated. People, who need assistance with their daily routine, such as older people, especially during illnesses that limit mobility, may become severely dehydrated. Dehydration results in orthostatic hypotension, due to reduction in the volume of blood in the body.

Inactivity during illnesses, especially if the patient is bedridden, causes fluid accumulation in the legs, due to its not being pumped up to the heart by the movement of leg muscles. This makes less blood available to the heart for pumping, reducing the pressure in the arteries.

Drugs such as calcium channel blockers, ACE inhibitors, beta blockers, alpha blockers, nitrates etc., which cause dilatation of arterioles, may result in hypotension as the dilated arterioles accommodate more blood, leaving less quantity in the major arteries. Many antidepressant drugs and alcohol also causes vasodilatation, which can result in hypotension. Any damage to the nerves which control vasodilatation and constriction impairs their ability to regulate the size of the arterioles, according to the demand of the body’s compensatory mechanism and may precipitate low blood pressure. Nerve damage could have happened due to a spinal cord injury or due to disorders such as amyloidosis and diabetes.

 Increase in body temperature, either due to fever or because of warm weather or warm clothing, causes the veins to dilate in an effort to dissipate heat from the body; but, it may also lower blood pressure. Heavy meals draw blood towards the digestive system to aid in digestion and absorption of nutrients, leaving a deficit in the main arteries. Exercise and other strenuous activities cause vasodilatation in the concerned muscles, to meet the extra demand for oxygen and glucose in the muscle cells, resulting in hypotension.

Symptoms and Diagnosis of Orthostatic hypotension

People may feel dizzy, light headed or confused when they suddenly get up from a sitting position or when they get up from bed, due to orthostatic hypotension. Temporary blurring of vision may also occur. Fatigue, alcohol consumption or a heavy meal may exacerbate the symptoms. If the amount of blood reaching the brain is severely reduced due to hypotension, it causes fainting, which is called orthostatic syncope. Even seizures may occur due to oxygen deficit in the brain.

Diagnosis of orthostatic hypotension can be made from the association of symptoms and the time of their incidence. Blood pressure can be measured when the person is in an upright position and when the person is lying down. If blood pressure which has been low when measured in sitting position returns to normal level when lying down, orthostatic hypotension can be confirmed. The reason behind this condition should be assessed to decide on the treatment.

Treatment of Orthostatic hypotension

Maintaining the volume of blood is important for avoiding hypotension. Avoiding alcohol and drinking other fluids liberally may help. Some people benefit from extra intake of salt, but it should be done with caution, as it may result in hypertension and heart failure, especially in older people. If symptoms are too severe, hormones like fludrocortisone can help in increasing blood volume through salt retention; but it may not be advisable, especially for older people and those who have heart disease, due the additional risk of causing heart failure. Since loss of potassium results from taking fludrocortisones, potassium supplements should be taken along with it. Midodrine, a drug which can constrict arterioles, when taken concurrently with fludrocortisones, can prevent hypotension. Certain other drugs such as clonidine and pindolol, may be effective in relieving orthostatic hypotension in some cases, but they have unpleasant side effects, especially in older people.

 Orthostatic hypotension can be managed even if it cannot be cured, by taking certain precautions such as avoiding sudden changes in posture. People who have orthostatic hypotension should sit up or stand up gradually and deliberately. Also, they should avoid standing in the same position for extended periods. Moving the legs frequently and wearing elastic stockings which extend up to the waist, may reduce accumulation of blood in the legs. While recuperating from a long illness involving bed rest, periods of sitting up on the bed should be increased very gradually.

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What Are The Causes Of Fainting

Fainting (syncope) is a temporary loss of consciousness, which occurs suddenly, resulting from decreased blood flow to the brain, often due to hypotension.

  • Abnormalities in the brain’s function cause fainting.
  • Prior to fainting, symptoms such as light-headedness and giddiness may occur.
  • Heart function testing and tilt-table testing are done to detect the cause.\
  • Soon after fainting, consciousness may be restored by lying down and resting for a short while, but the cause of the fainting episode needs to be investigated and treated.

Fainting occurs due to insufficient blood supply to the brain, most often resulting from blood pressure which is too low to pump the blood all the way up to the brain. Since the head is much higher than the heart, blood has to reach the brain against the force of gravity. The blood pressure in the arteries is responsible for the flow of blood upwards and in to the brain. Hence, it is the first organ to be affected by low blood pressure.

Causes Of Fainting

People lose consciousness when brain function is disrupted, usually due to reduced flow of blood to the brain, often resulting from hypotension. Hypotension may have developed due to various reasons, including disorders of the heart such as heart failure, heart attack, arrhythmias that are too fast, too slow or irregular. Severe blood loss also can cause low blood pressure resulting in fainting. If flow of blood to the brain is impaired due to a blood vessel disorder, it may cause fainting. Loss of consciousness due to seizures, which result from abnormal electrical activity in the brain, is not considered as fainting even though fainting and seizures are very similar outwardly and it is difficult to distinguish one from the other.

Problems with the Heart’s Pumping: Heart’s blood pumping capacity may be impaired due to many reasons. If the heart is not able to pump sufficient quantity of blood to meet the demand for oxygen and nutrients by the body, it is termed heart failure. Heart failure may occur due to valve disorders or abnormal heart rhythms; and people with heart failure may not feel any difficulty while resting. But, when the demand for blood supply is increased due to any exertion, the heart’s insufficiency becomes apparent and the person feels light headed or actually faints, because enough blood is not reaching the brain. This condition is called exertional fainting or effort syncope.

Instead of fainting during exercise, some people faint after they stop exercising. This may seem peculiar, but there is a valid reason for that. During exercise, the heart rate increases to enhance the cardiac output to meet the additional requirement, due to which the blood pressure remains high enough to prevent fainting. But as soon as the person stops exercising, the heart rate returns to normal, but the arterioles which had become dilated to supply extra amount of glucose and oxygen to the working muscles during the exercise, remain dilated for some more time to help with tissue repair and removal of waste materials produced during muscle activity. Since more blood remains in dilated arterioles even after the exercise, this continued demand in the muscles, combined with the reduced heart output, results in low blood pressure and less blood being available to the brain, causing fainting.

 Hypertrophic cardiomyopathy, which is a disorder of the heart muscle, can also be a reason for fainting during exercise. Aortic valve stenosis, when severe, also causes fainting. Disorders such as these are not limited to any age group, but they often occur in people who have high blood pressure. Without proper treatment they can be fatal.

Low Volume of Blood:  If the circulating volume of blood becomes too low due to excessive bleeding and severe dehydration, low blood pressure may develop. Dehydration may be due to copious sweating and urination, Addison’s disease, severe diarrhea and use of diuretics combined with insufficient rehydration, especially during summer.  Older people with reduced mobility and those who suffer from dementia often fail to drink enough water to maintain adequate fluid levels in the body, resulting in fainting.

Vagus Nerve Stimulation:  The vagus nerve which enervates chest, neck and intestine slows down the heart rate when stimulated. Vagus nerve stimulation results in nausea and skin that feels cold and clammy to touch; if the heart rate becomes too low, it may result in fainting which is termed vasovagal syncope.  Emotional stress such as fear and distressing sights as well as physical stress from strained bowel movements, urination or vomiting may stimulate the vagus nerve, resulting in fainting. Swallowing vigorously also may have the same effect. Micturition syncope is one such condition, in which fainting occurs during urination or immediately after.

Reduced Blood Flow: Cough syncope, is fainting due to the strain of coughing, because the blood flow back into the heart becomes reduced. Weight lifters’ syncope, due to the strain of lifting heavy weights without proper breathing, is also due to the reduction of blood flow into the heart. Micturition syncope in older people may result from having to strain too much to pass urine, due to the enlargement of prostate gland, in addition to vagus nerve stimulation.

 Problems with Blood Pressure: Orthostatic syncope or postural syncope is a type of fainting that occurs when people suddenly change their body posture, for instance, quickly getting up from a sitting position or vice versa. This disorder, mainly occurring in older people, results from orthostatic hypotension. It is due to the slow response of body’s compensatory mechanism to restore to normal, the low blood pressure in the arteries because gravity has caused blood to accumulate in the legs. Parade ground syncope is a similar occurrence when the blood accumulated in the legs does not return to the heart because of the inactivity of the leg muscles, causing hypotension and fainting. Postprandial hypotension, occurring usually in older people after a meal, also may cause fainting.

Other Problems: Hyperventilation or very fast breathing, possibly due to anxiety or severe emotional distress, may result in hyperventilation syncope. Rapid breathing lowers the level of carbon dioxide in the body, which results in the constriction of arterioles in the brain, causing giddiness or fainting.

Fainting may be caused by a mild stroke, when the blood flow is decreased to certain areas of the brain, but it is seldom seen in younger people. Anemia may cause fainting due to the inadequate amount of the oxygen carrying molecule, hemoglobin, in the blood. Lung disorders, which affect the oxygenation of blood in the lungs, reduce the amount of oxygen made available to the tissues, leading to fainting due to oxygen starvation in the brain. Hypoglycemia or less than normal levels of blood sugar in people with diabetes, often caused by antidiabetic drugs, can also result in fainting.

Some of the drugs used for the treatment of heart failure, angina and high blood pressure can cause hypotension that may lead to fainting. Hence, it is very important to adjust the dosage of such drugs, especially that of antihypertensive drugs.

Symptoms

Prior to fainting, warning signs such as a light-headed or dizzy feeling may be felt, particularly if the person is already standing or has suddenly got up. When the person falls down due to fainting, the head may come to the same level as the heart, and blood flow to the brain may improve enough for him to regain consciousness in a short while. There may be a temporary improvement in the blood pressure but if the person tries to get up, again he may lose consciousness.

Fainting due to arrhythmia happens suddenly, without the usual warning signs, and disappears just as suddenly. But palpitations due to fast arrhythmias may be felt before the person faints.

Vasovagal syncope usually has many warning signals such as sweating, pale, cold and clammy skin, blurred vision, yawning and nausea. Very slow pulse resulting from the effect of vagus nerve stimulation significantly reduces blood supply to the skin, making the person look deathly pale.

Fainting due to hypoglycemia sets in slowly and the recovery is also just as slow. Hypocapnia or low levels of carbon dioxide, also leads to fainting that sets in slowly, following a sensation of pins- and- needles felt in the area surrounding the lips as well as in the tips of fingers, which may be considered a warning signal.

Diagnosis Of fainting

The cause of fainting has to be detected as soon as possible, since some of the causes are extremely dangerous conditions that require immediate medical intervention. Fainting due to arrhythmias, aortic valve stenosis, heart failure and heart attack are potentially fatal, while some other causes of fainting require only minimal medical care or even just a period of rest and relaxation.

The descriptions provided by those who have witnessed the person fainting, may help the doctor assess whether physical or emotional stress could have caused the fainting. Medical history of the patient, details of the medications taken and the symptoms such as chest pain, palpitations or shortness of breath which may have preceded the episode, may help the doctor with diagnosis. If fainting seems to have occurred due to some disorders of the cardiovascular or nervous systems, further tests are conducted to detect the exact cause, and to start immediate remedial action.

If symptoms such as sweating or nausea, accompanied by pale, cold and clammy skin were felt prior to fainting, it may be a vasovagal syncope, which is not serious and require no further investigation or treatment. People who have fainted due to emotional stress will also recover without further intervention.

An ECG or electrocardiogram can record the heart’s electrical activity, to detect heart disorders that may have caused the fainting. A portable ECG machine called Holter monitor is worn by the patient, for continuous monitoring of the heart’s electrical activity over a period of time, as the patient goes about his routine activities, to see if fainting is due to exertion.

The structural as well as the functional abnormalities of the heart can be detected by echocardiography which produces ultrasound images of the heart. Hypoglycemia and anemia can be detected by blood tests. Re-creating a fainting episode artificially, in a safe, monitored environment, often helps to confirm whether the suspected cause. Pressing the carotid sinus, to produce a false sensation of high blood pressure in the arteries, may trigger the body’s blood pressure controlling mechanism to lower the blood pressure. Fainting may result, and during this time the heart function is closely monitored through ECG, to establish the connection, if any, between heart’s function and fainting. Patient is also made to inhale and exhale deeply, in quick succession, to determine if the fainting was caused by hyperventilation due to emotional stress.

In tilt table testing, which helps detect the cause of fainting, the patient strapped to a motorizes tilt table is tilted into an upright position for about 45 minutes, while the heart rate and blood pressure are monitored for any decease in blood pressure. Using isoproterenol to stimulate the heart, before doing this test, gives a more accurate result.

 A seizure due to abnormal electrical activity in the brain may cause loss of consciousness, but it is considered to be different from fainting, and the treatments also differ. Slower recovery following an episode of unconsciousness, and persistent drowsiness even after recovery, are characteristic features of seizure. EEG or electroencephalography, which is a test that records brain’s electrical activity, may help in diagnosis.

Treatment

If the reason for fainting is not a very serious condition, allowing the patient to rest for some time in a horizontal position, preferably with the legs at a slightly higher plane, may be all that is necessary to restore consciousness. Even after recovery, the person should not be made to sit up nor should be carried in sitting position, as recurrence is likely, if the blood flow to the brain is again reduced due to the upright position.

Arrhythmias can be corrected by various means; an implantable pacemaker helps to correct slow heart rate, beta blockers such as metoprolol or asatenolol can reduce a fast heart rate, an implantable defibrillator can change an irregular arrhythmia to normal heart rhythm. Heart valve disorders can be corrected surgically.

Fainting due to hypoglycemia in people who are diabetic can be avoided, by adjusting the antidiabetic medication, taking meals at regular intervals and carrying some sweets to restore glucose levels when the symptoms of hypoglycemia appear. Anemia can be avoided by taking balanced meals or can be treated with iron supplements. Intravenous administration of fluids helps to restore blood volume, if fainting has occurred due to blood loss.

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What is Low Blood Pressure (Hypotension)

Low blood pressure or hypotension is a condition in which the blood pressure in the arteries is much lower than the normal range.

  • Hypotension may be due to the malfunctioning of the body’s blood pressure controlling mechanism, due to certain disorders or drugs.

The body has a natural mechanism by which it maintains a normal blood pressure reading. Too high a blood pressure can cause damage to the arteries and the smaller arterioles, even causing their rupture, whereas too low a pressure in the arteries affects blood distribution to the different parts of the body. If blood distribution is compromised, tissues become starved of oxygen and essential nutrients and the waste products accumulate in the tissues. Extremely low blood pressure is a potentially fatal condition, which can result in shock and eventually death. At the same time, people with blood pressure nearer to the lower limit within the normal range, seem to have a higher life expectancy than those whose blood pressure is nearer to the upper limit, within the normal range.

The body controls the blood pressure by either changing the size of the smaller veins and arterioles, or by adjusting the amount of circulating blood in the body. It can also increase or decrease the volume of blood being pumped by the heart by changing the cardiac output. By activating any of these mechanisms, the body restores blood pressure to normal levels after an increase or decrease, during exercise or sleep respectively.

Veins dilate to increase their capacity and constrict to decrease their capacity to hold blood. When their capacity is reduced by constriction, more blood returns to the heart and from where it will be pumped into the arteries, increasing the arterial pressure.

When arterioles dilate, the blood pressure within them lowers and when they constrict, the pressure increases within.

The amount of blood pumped by the heart per minute can be controlled, either by increasing or decreasing the number of heart beat per minute, or by changing the force with which each contraction takes place.

The total circulating volume of blood can determine the blood pressure in the arteries, when all other factors such as the size of the vessels and the cardiac output remain the same. By increasing or decreasing the amount of urine excreted by the kidneys, the volume of circulating blood can be controlled.

The baroreceptors are a group of cells within the arteries, which act as pressure sensors, keeping track of the blood pressure within. They play an important role in regulating blood pressure, especially those in the larger neck and chest arteries. Changes in blood pressure are detected by the baroreceptors, and the body’s mechanism to counteract the changes is activated by nerves of the sympathetic system, which carry the required instructions to various organs.

When hypotension develops:

  • The heart increases the rate and force of heartbeats, thus increasing the amount of blood pumped into the arteries, elevating blood pressure quickly.
  • The arterioles constrict to increase the blood pressure within the arteries.
  • The veins constrict to bring in more blood for the heart for pumping into the arteries to increase blood pressure.
  • The kidneys decrease their output of urine, preventing further fluid loss. This is a slow acting blood pressure controlling mechanism.

When there is severe blood loss, blood pressure plummets due to the reduction in the blood volume. The body’s homeostatic mechanism kicks in to arrest the drop in blood pressure, by making the heart to beat faster and more forcefully, thus increasing cardiac output. Urine production by the kidneys is reduced to avoid fluid loss. Blood supply to the bleeding site is reduced by constricting the veins, and the arterioles constrict to increase blood pressure within the arteries. After the bleeding stops, the fluid from the tissues moves into the blood vessels to increase the volume of blood and elevating the blood pressure. Eventually, with the production of blood cells by the bone marrow, the lost blood is fully compensated for. However, if the blood loss is rapid, compensatory mechanisms do not get time to restore blood pressure before shock develops.

Causes of Low Blood Pressure

Hypotension may result from various disorders of the heart such as heart valve disorders, heart attack, fast or slow or irregular arrhythmias. Certain toxins produced during bacterial infections cause the arterioles to dilate and result in low blood pressure. Bleeding and severe dehydration can reduce the circulating volume of blood and cause hypertension. If the kidneys are not able to regulate fluid excretion due to some disorder, excess fluid loss may result in low blood pressure. Neurologic disorders that impair the conduction of stimuli and messages between the sensory receptors and the target organs, interferes with the action of the compensatory mechanisms, thus reducing the body’s capacity to normalize low blood pressure. Slowing down of the body’s blood pressure controlling mechanism due to aging, may make it incapable of meeting the demand, when low blood pressure develops due to some reason.

Symptoms

The brain is the first organ to be affected by low blood pressure, because a certain minimum blood pressure is necessary for the blood to reach the head, which is located much above the heart. The reduced blood supply to the brain results in symptoms usually associated with low blood pressure such as dizziness and fainting. Falling down due to fainting, brings the head at the same level with the heart, helping restore blood flow to the head and minimizing injury to the brain, till the blood pressure returns to normal.

When the supply of blood to the heart muscle decreases due to low blood pressure, angina or shortness of breath may result.

When blood pressure falls below certain minimum levels, the organs of the body shut down and a potentially fatal condition called shock occurs.

If the low blood pressure is a result of an infection, fever may be present, but it is unrelated to the condition itself.

There are certain symptoms which result from the body’s attempts at elevating low blood pressure. When heart beats faster, and with more force, to increase cardiac output, palpitations may be felt. While constriction of arteries helps to increase the blood pressure within the arteries, it also restricts blood flow to the skin and the limbs, which causes them to become cold and blue.

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