What is low blood pressure (hypotension)?
Low blood pressure or hypotension refers to the fall in blood pressure below normal. It is a condition in which the action of the heart, in forcing the blood through the arteries, is weak. This may be a direct outcome of a weakened and devitalized system. While the normal limits are defined by the World Health Organisation as 140 mm / gh systolic and 90 mm/gh diastolic, it has now been reduced to 120 mm/gh systolic and 80 mm/gh diastolic in the US. Anything above that is high blood pressure or hypertension. Anything below is the low blood pressure.
Blood pressure is given as two numbers (140/90, for example) that describe the amount of pressure inside the arteries of the body. Arteries are blood vessels that carry blood from the heart to the rest of the body. Blood pressure is fairly easy to measure. The pressure is related to blood flow inside the arteries, much like the pressure inside a hose is related to water flowing through it. Many conditions can cause low blood pressure. Low blood pressure can be broadly defined as any blood pressure that is below the normal expected for an individual in a given environment. Low blood pressure, therefore, is a relative term. Blood pressure varies greatly with activity, age, medications, and underlying medical conditions. Low blood pressure is also referred to as hypotension.
Low blood pressure that does not cause symptoms is generally considered to be a sign of good cardiovascular health because there is less stress on the heart and blood vessels. However, there are a number of forms of low blood pressure that require diagnosis and treatment. People may seek treatment for low blood pressure if they experience symptoms such as dizziness or syncope (fainting) from lack of oxygen to the brain. Low blood pressure may be due to medications (e.g., blood pressure medications) or other causes, and changing medications or other treatments may be necessary.