How
Is Blood Pressure Checked?
Having
your blood pressure checked is quick, easy, and painless. Your
blood pressure is measured with an instrument called a sphygmomanometer
(sfig-mo-ma-nom-e-ter).
It
works like this: A blood pressure cuff is wrapped around your
upper arm and inflated to stop the blood flow in your artery for
a few seconds. A valve is opened and air is then released from
the cuff and the sounds of your blood rushing through an artery
are heard through a stethoscope.
The
first sound heard and registered on the gauge or mercury column
is called the systolic blood pressure. It represents
the maximum pressure in the artery produced as the heart contracts
and the blood begins to flow. The last sound heard as more air
is released from the cuff is the diastolic blood
pressure. It represents the lowest pressure that remains within
the artery when the heart is at rest.
What
Do the Numbers Mean?
Blood
pressure is always expressed in two numbers that represent the
systolic and diastolic pressures. These numbers are measurements
of millimeters (mm) of mercury (Hg). The measurement is written
one above or before the other, with the systolic number on the
top and the diastolic number on the bottom. For example, a blood
pressure measurement of 120/80 mm Hg is expressed verbally as
"120 over 80." See the table below which shows categories
for blood pressure levels in adults.
If
your blood pressure is less than 140/90 mm Hg, it is considered
normal. However, a blood pressure below 120/80 mm Hg is even better
for your heart and blood vessels. People use to think that low
blood pressure (for example, 105/65 mm Hg in an adult) was unhealthy.
Except for rare cases, this is not true. High blood pressure or
"hypertension" is classified by stages and is more serious
as the numbers get higher.
| CATEGORIES
FOR BLOOD PRESSURE LEVELS IN ADULTS*
|
| (Age
18 Years and Older) |
| |
Blood
Pressure Level (mm Hg) |
| Category
|
Systolic |
Diastolic |
| Normal |
<130 |
<85 |
| High
Normal |
130-139 |
85-89 |
| High
Blood Pressure |
|
Stage 1 |
140-159 |
90-99 |
|
Stage 2 |
160-179 |
100-109 |
|
Stage 3 |
>180 |
>110 |
*For
those not taking medicine for high blood pressure and not
having a short term serious illness. These categories are
from the National High Blood Pressure Education Program.
(> means greater than or equal
to)
|
What
Causes High Blood Pressure?
For
most people, there is no single known cause of high blood pressure.
This type of high blood pressure is called "primary"
or "essential" hypertension. This type of blood pressure
can't be cured, although in most cases it can be controlled.
That's why it's so important for everyone to take steps to reduce
their chances of developing high blood pressure.
In
a few people, high blood pressure can be traced to a known cause
like tumors of the adrenal gland, chronic kidney disease, hormone
abnormalities, use of birth control pills, or pregnancy. This
is called "secondary hypertension." Secondary hypertension
is usually cured if its cause passes or is corrected.
