Low Blood Pressure

Low blood pressure (hypotension) is a relatively common problem, which is often caused by prescribed antihypertensive drugs. It is not always easy to state the hypotension as it is quite individual, but usually it is blood pressure measured below 100/60 mm Hg, which is accompanied with any clinical symptoms.


It is not as dangerous as high blood pressure, but it can significantly impair a person's quality of life. It should be also noted that sudden drop of blood pressure may accompany some life-threatening conditions.


Probably the most common cause of hypotension is too strong effect of antihypertensive drugs prescribed to patients with hypertension. In addition, the blood pressure may be reduced by dehydration (lack of water in the blood vessels) and some people suffer from sudden decrease of blood pressure when changing position from horizontal to vertical (i.e. when getting up in the morning). Quite special issue is a life-threatening decrease of blood pressure being accompanied with increased pulse rate in the so-called shock conditions.


Most symptoms are associated with a poor blood supply to the brain due to inadequately low pressure. The person feels dizzy, suffers from nausea, fatigue, general weakness, excessive sweating, exercise-related shortness of breath and occurrence of flashing lights in the visual field. Stronger or long-lasting hypotension may cause loss of consciousness and total collapse.


The diagnosis is made by basic measurement of the blood pressure by a mercury or electronic device. During the investigation, it is important to determine whether the patient is taking medication for high blood pressure and if the collapse has not been preceded by a quick change of position to vertical. It is also necessary to exclude the possibility of shock conditions and to perform at least a basic neurological examination to rule out a stroke. Especially in the elderly it is important to exclude dehydration.


The first aid in a bout of hypotension is to put the victim into a horizontal position and lift his or her legs. This maneuver leads to improvement of blood circulation to the brain and the symptoms usually quickly disappear. Less severe cases of hypotension respond usually well to administration of intravenous infusions that increase the blood volume and the blood pressure.


Hypotension in patients using antihypertensive drugs should be solved with reduction or even discontinuation of the therapy. Patients sensitive to changes of the body position must be careful, especially when getting up in the morning (first slowly sit up and then stand up carefully). Increased coffee intake is in this case reasonable as it can help in maintaining the blood pressure. Older people should be encouraged to increase their fluid intake as they usually do not feel the urge of thirst.


Patients in shock conditions must be treated in intensive care units with monitoring of basic vital functions, intravenous hydration and treating the underlying cause of the shock. Blood pressure may be elevated by special intravenous medicines such as dobutamine and norepinephrine, but it is only a temporary solution.


Jiri Stefanek, MD  Author of texts: Jiri Stefanek, MD
 Contact: jiri.stefanek@seznam.cz
 Sources: basic text sources