HOMEOSTATIC IMBALANCE OF BLOOD PRESSURE

Blood Pressure

Blood Pressure

High blood pressure, also called hypertension, is elevated pressure of the blood in the arteries. Hypertension results from two major factors, which can be present independently or together:

•The heart pumps blood with excessive force

•The body's smaller blood vessels (known as the arterioles) narrow, so that blood flow exerts more pressure against the vessels' walls

Although the body can tolerate increased blood pressure for months and even years, eventually the heart may enlarge (a condition called hypertrophy), which is a major factor in heart failure.

Such pressure can also injure blood vessels in the heart, kidneys, the brain, and the eyes. Two numbers are used to describe blood pressure: the systolic pressure (the higher and first number) and thediastolic pressure (the lower and second number). Health dangers from blood pressure may vary among different age groups and depending on whether systolic or diastolic pressure (or both) is elevated. A third measurement, pulse pressure, may also be important as an indicator of severity.

Blood pressure is measured in millimeters of mercury (mm Hg). Ac-cording to current adult guidelines, blood pressure is categorized as normal, prehypertensive, and hypertensive (which is further divided into Stage 1 and 2, according to severity). People in normal health should have a blood pressure reading of 120/80 mm Hg or less. High blood pressure is generally considered to be a blood pressure reading greater than or equal to 140 mm Hg (systolic) or greater than or equal to 90 mm Hg (diastolic). Blood pressure readings in the prehypertension category (120-139 systolic or 80-89 diastolic) indicate an increased risk for developing hypertension.

Current guidelines for children are based on percentile ranges for a child's body size. Hypertension is defined as average systolic and diastolic readings that are greater than the 95th percentile for gender, age, and height on at least three occasions. Prehypertension in children is diagnosed when average systolic or diastolic blood pressure levels are at least in the 90th percentile but less than the 95th percentile. For adolescents, as with adults, blood pressure read-ings greater than 120/80 are considered prehypertensive. Increasing rates of childhood obesity have lead to higher than average blood pressure levels in children.

American expert groups recommend treating any blood pressure above normal. Some experts are concerned, however, that such guidelines may unnecessarily increase the use of anti-hypertensive drugs. It is important that patients establish a relationship with a doctor whom they trust, to help them determine individual blood pressure goals and treatment regimens. For some patients, a decrease of a few points in blood pressure may not be worth the side effects caused by higher doses of anti-hypertensive drugs.

Systolic Blood Pressure. The systolic pressure (the first and higher number) is the force that blood exerts on the artery walls as the heart contracts to pump out the blood. High systolic pressure is now known to be a greater risk factor than diastolic pressure for heart, kidney, and circulatory complications and for death, particularly in middle-aged and elderly ...