sphygmanometer

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blood pressure

In the United States, blood pressure is usually measured in millimeters of mercury (mmHg). Two measurements are made. The first number is the pressure as the heart pumps (systolic pressure). The second number is the pressure between beats (diastolic pressure). The two can be thought of as the maximum and minimum pressure. 

High blood pressure (hypertension) is associated with various diseases, such as stroke and heart attacks. In 2003, a committee convened by the National Heart, Blood and Lung Institute issued the following guidelines:┬╣

Average diastolic
blood pressure
Average systolic blood pressure
less than 120 120–139 140–159 160 and higher
less than 80 normal prehypertension hypertension,
stage 1
hypertension,
stage 2
80–89 prehypertension prehypertension hypertension,
stage 1
hypertension,
stage 2
90–99 hypertension
stage 1
hypertension,
stage 1
hypertension,
stage 1
hypertension,
stage 2
100 and higher hypertension,
stage 2
hypertension,
stage 2
hypertension,
stage 2
hypertension,
stage 2

Older Stagings

Formerly the stages of hypertension were described as mild, moderate, and severe. Unfortunately, describing a condition as “mild” encourages people to do nothing about it. In 1992, the National High Blood Pressure Education Program released the staging shown in the table below. The numbers 1 to 4 represent increasingly greater risk.

Average diastolic Average systolic blood pressure
<120 120–129 130–139 140–159 160–179 180–209 >209
<80 optimal normal high normal 1 2 3 4
80–84 normal normal high normal 1 2 3 4
85–89 high normal high normal high normal 1 2 3 4
90–99 1 1 1 1 2 3 4
100–109 2 2 2 2 2 3 4
110–119 3 3 3 3 3 3 4
>120 4 4 4 4 4 4 4

Physicians came to believe that people in the "high normal" group actually have a significantly increased risk of heart disease. Some results┬▓ of the Framingham Heart Study, which has followed thousands of persons over half a century, suggest, for example, that women in the "high normal" group were twice as likely to have a "cardiovascular event" as women whose blood pressure was below 130 mmHg systolic and 85mmHg diastolic.

1. Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation and Traetment of High Blood Pressure.
Journal of the American Medical Association (JAMA), May 21, 2003.

2. Ramachandran S. Vasan, Martin G. Larson, Eric P. Leip, Jane C. Evans, Christopher J. O'Donnell, William B. Kannel, and Daniel Levy.
Impact of High-Normal Blood Pressure on the Risk of Cardiovascular Disease.
New England Journal of Medicine
, volume 345, number 18, pages 1291-1297. 1 November 2001.

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