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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Yasser Elnahas

MD, PHD, Professor Of CardioVascular Surgery
Dr. Yasser Elnahas, Is an associate Professor of Cardiovascular Surgery. Dr. Elnahas was trained as a fellow At Texas Heart Institute And Mayo Clinic Foundation.Dr. Elnahas is dedicated to educating the general public about different disease conditions and simplifying the medical knowledge in an easy to understand terminology.

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One Response to What Is Orthostatic hypotension, Its Causes and Treatment

  1. Reynaldo Verret says:

    Most people who eat a healthy diet should get enough potassium naturally. However, many Americans don’t eat a healthy diet and may be deficient in potassium. Low potassium is associated with a risk of high blood pressure, heart disease, stroke, arthritis, cancer, digestive disorders, and infertility. For people with low potassium, doctors sometimes recommend improved diets — or potassium supplements — to prevent or treat some of these conditions.:;.’

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