Hypotension

Low blood pressure.

A condition in which the pressure of the blood is unusually low.

Blood pressure that is abnormally low (in adults, usually less than 90 mm systolic); it may result from hemorrhage, excessive fluid loss, heart mal¬ function, Addison’s disease, or other disorder. In some people blood pressure drops when they rise from a horizontal position (orthostatic hypotension). Transient hypotension may cause light-headedness and syncope. Severe hypotension leads to inadequate blood circulation and shock.

Low blood pressure. Physicians define hypotension as blood pressure below 90/60 millimeters of mercury (mm Hg). Many normal people may have low blood pressure, particularly young, slender women. However, hypotension can indicate problems with the heart or nervous system, such as hypothyroidism (an underactive thyroid), diabetes mellitus, heart disease, hypoglycemia (low blood sugar), liver disease, or anemia. Hypotension can also result from the overdosing of medication to control blood pressure, high or low body temperature, substantial blood loss, allergic reaction (for example, to a bee sting), severe blood infection, or dehydration. Temporary hypotension can result from heavy menstrual bleeding, unusually hot weather, overheating (for example, from too much time in a hot tub, a sauna, or the sun), or sudden emotional shock.

A condition in which the arterial blood pressure is abnormally low. It occurs after excessive fluid loss (e.g. through diarrhea, bums, or vomiting) or following severe blood loss (hemorrhage) from any cause. Other causes include myocardial infarction, pulmonary embolism, severe infections, allergic reactions, arrhythmias, acute abdominal conditions (e.g. pancreatitis), Addison’s disease, and drugs (e.g. an overdose of the drugs used to treat hypertension).

Low blood pressure. Some healthy individuals with a normal cardiovascular system have a permanently low arterial blood pressure for their age. What blood-pressure reading constitutes hypotension is arguable, but a healthy young person with figures below 106 mm Hg systolic and 65 mm Hg diastolic could be described as hypotensive. For a healthy 60 year old, comparative figures might be 120/80. The most common type of hypotension is called postural, with symptoms occurring when a person suddenly stands, particularly after a period of rest or a hot bath. It results from the muscular tone of blood vessels becoming relaxed and thus unable to respond quickly enough to the change in posture, the consequence being a temporary shortage of arterial blood to the brain. Symptoms of dizziness, occasional fainting, and nausea may occur. Older people are especially vulnerable and may fall as a result of the sudden hypotension. Some drugs anti-hypertensives and antidepressants can cause hypotension. People with diabetes mellitus occasional develop hypotension because of nerve damage that affects the reflex impulses controlling blood pressure. Any severe injury or burn that results in serious loss of blood or body fluid will cause hypotension and shock. Myocardial infarction or failure of the adrenal glands can also cause these symptoms, as can a severe emotional event that causes shock.

An abnormal condition in which the blood pressure is too low for normal functioning.

Hypotension is a medical term used to describe low blood pressure. A common type of this condition, called postural hypotension, presents symptoms when an individual suddenly stands up or sits down. Usually, our blood pressure adjusts with changes in body posture, but for those with postural hypotension, it decreases. This condition could be a side effect of certain medications like antidepressants or antihypertensive drugs, or it might be associated with conditions like diabetes mellitus. Severe cases of hypotension, referred to as acute hypotension, can be a characteristic of shock, potentially caused by a serious injury or diseases like a heart attack or adrenal failure.