Medically Reviewed By:
Last Updated on May 5, 2023 by Shabnam Sengupta
Hypotension or low blood pressure is a condition in which the blood pressure falls below the recommended normal level of blood pressure of 120/80 mmHg.
There are two categories of blood pressure. They are:
- Systolic blood pressure: This is the blood pressure that occurs due to forceful contraction of the heart.
The normal level should be 80-120 mmHg.
- Diastolic blood pressure: This is the blood pressure that occurs when the heart is in a resting state.
The normal level should be 60-80 mmHg.
Blood pressure is generated due to two things – the running blood volume inside the body and the diameter of the blood vessels. A decrease in blood volume and an increase in the blood vessel diameter (vasodilation) will lead to a fall in blood pressure. If the blood pressure is usually low, no symptoms or harm occurs. However, a sudden fall in the blood pressure can cause a reduction in the blood supply to the brain and other organs leading to various signs and symptoms.
Symptoms of hypotension or low blood pressure
If low blood pressure is present for a very long duration of time, then the patient will be asymptomatic for the most part. However, a sudden fall in the blood pressure due to any reason can cause the patient to experience various signs and symptoms like:
- Dizziness
- Lightheadedness
- Fatigue
- Confusion
- Blurred vision
- Fainting
- Nausea
- Cold and clammy skin
- Pale skin
Causes and risk factors
- Not drinking enough water leads to dehydration and decreased blood volume
- Heart conditions like arrhythmia, heart failure
- Severe vomiting and diarrhoea affect the blood volume
- Autonomic imbalance
- Severe infections can cause septicaemia and anaphylactic shock
- Severe blood loss during surgery or injury can affect the circulatory blood volume
- Drugs like diuretics, anti-anxiety medications etc
- Pregnancy
- Lack of nutrients like vitamins and iron needed for blood formation
- Alcohol also causes a state of dehydration in the body
Types of hypotension or low blood pressure
There are several types of hypotension. They are:
- Orthostatic hypotension or postural hypotension: In the normal state, blood distributes uniformly throughout the body when a person lies down or are sitting. But when they suddenly stand up, there is a pooling of blood in the legs due to gravity. Due to the body’s mechanism to compensate it, there is a contraction of blood vessels to normalise the blood pressure. However, in patients with this type of hypotension, the compensatory mechanism is faulty due to which there is sudden falling in pressure on standing.
- Post-prandial hypotension: This may occur after a person consumes a heavy meal. Normally, the blood in a person’s body flows towards the digestive tract after a meal and the vasoconstriction (the narrowing of the blood vessels) in the rest of the body equalises the pressure. However, this fails to cause a drop in blood pressure after a meal in the people with this type of hypertension.
- Neurally mediated hypotension: This type of hypotension develops on excessive standing or excessive emotional response.
- Due to drugs: Certain drugs cause widening of blood vessels on consumption causing the blood pressure to drop all of a sudden.
- Severe hypotension: This usually follows after a severe allergic reaction when the blood vessels dilate causing extensive drop in the blood pressure and shock.
Complications
Hypotension can cause fainting and sudden falls leading to physical injuries. Consistent low blood pressure decreases the blood perfusion of an organ causing hypoxia and damage due to a shortage of oxygen supply. This state where the blood pressure is excessively low and results in a decrease in the oxygen supply of an organ is called shock.
Diagnosis of hypotension or low blood pressure
Making the diagnosis is simple. The cuff of the sphygmomanometer (an instrument for measuring blood pressure) is wrapped around the patient’s arm and the blood pressure is measured. In the case of consistently low blood pressure, underlying pathology needs to be evaluated and treated.
Blood pressure less than 90/60 (S/B) would be low blood pressure or hypotension.
Additional tests can be:
- Blood tests: To assess hypoglycaemia, anaemia
- ECG: to check the functioning of the heart
- The tilt table test is to diagnose orthostatic hypotension in which the blood pressure varies according to the tilt or position of the body.
Treatment
The doctor will try to treat the underlying cause of the hypotension if present. There can several such causes like anaemia, endocrine dysfunction or any heart condition.
Besides this, some general measures are:
- Consumption of more water
- Consumption of more salt
- Stopping any drug which might be causing hypotension
- Standing up slowly
- Consuming small meals at a time
- Avoiding alcohol
- Wearing of compression stalking in case of varicose veins
- Limited consumption of caffeine
- Avoid standing for a very long period of time
- Avoid sitting with your legs crossed for very long
If with the above-mentioned modification the blood pressure isn’t improving, then:
- intravenous fluid administration can be done to increase the blood volume;
- vasoconstrictor drugs can be used; and
- blood volume-improving drugs like fludrocortisone can be used.
Prevention
- Drink more water and avoid alcohol.
- Eat small and low carbohydrate meals.
- Exercise regularly.
- Eat healthy with blood-forming nutrients in it.
- Pay attention to body positions and change them slowly.
- Avoid standing for long periods.
- Avoid straining in toilets.
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