Hypotension (Low Blood Pressure)

Definition

Hypotension is the medical term for low blood pressure. The normal range of blood pressure is defined as 120/80 mm Hg, in which the numerator refers to the blood pressure during a heartbeat (when the heart is contracted) and the denominator denotes blood pressure in between heartbeats (when the heart is relaxed). In hypotension, the blood pressure usually drops below 90/60 mm Hg. Even a small drop in blood pressure below 60mm Hg could be dangerous since blood and oxygen supply to the brain and other vital organs are drastically reduced.

Symptoms

The brain is usually the first organ to be affected by lowered oxygen supply due to hypotension. Therefore, the primary symptoms of hypotension result from dysfunction of the brain.

The following are the common symptoms:

  • Feeling dizzy and light-headed
  • Fainting
  • Confusion
  • Blurry vision
  • Drowsiness
  • Weakness

Since the symptoms of hypotension are vague and could occur in various other conditions, hypotension is diagnosed only when blood pressure is actually measured in a clinical setting.

Causes

Hypotension can be caused by various factors :

  • Orthostatic hypotension: This is caused by sudden changes in body position (like suddenly standing up from a sitting or lying position) and lasts for only a few seconds or minutes. Older adults with high blood pressure or Parkinson’s disease most commonly display orthostatic hypotension.
  • Neurally-mediated hypotension: This is caused by standing for long periods of time, resulting in pooling of blood in the veins of the lower part of the body. Children and young adults are the most common victims of neutrally-mediated hypotension.
  • Shock: Heavy loss of blood also results in hypotension and shock.
  • Drugs: Alcohol and certain drugs such as anti-depressants, diuretics, anti-anxiety medicines and painkillers also lower the blood pressure.
  • Heart defects: Blood circulation throughout the body depends on the normal functioning of the heart. Various defects of the heart (arrhythmias, heart attack and heart failure) can lead to lowered blood pressure and decreased blood circulation.
  • Diabetes mellitus: Advanced stages of diabetes are also associated with hypotension.
  • Anaphylaxis: Severe, life-threatening allergic reactions could be accompanied by hypotension.
  • Dehydration: Loss of fluids due to severe dehydration, vomiting or diarrhea reduces the volume of the blood. This loss of circulating blood volume causes hypotension.
  • Adrenal gland dysfunction (like Addison’s disease) could also cause hypotension because adrenal hormones are involved in maintaining normal blood pressure.

Treatment

Mild hypotension in healthy adults usually resolves by itself without any treatment. However, severe hypotension is a serious condition that requires immediate measures to normalize the blood pressure. Treatment options depend on the specific cause of hypotension.

  • Hypotension caused by shock or dehydration requires immediate blood volume restoration  by blood transfusion or rehydration therapy.
  • If drugs are the cause, then the doctor could advise stopping or changing medications.
  • Underlying medical conditions (like heart defects, diabetes, and allergic reactions) that result in hypotension should be treated appropriately.
  • Sudden changes in body position and standing for long periods of time should be avoided.
  • Increasing salt intake in the diet may also help in increasing the blood pressure.
  • In some cases, medicines such as beta blockers, selective serotonin reuptake inhibitors, or fludrocortisones may be prescribed.

More Related Topics