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How To Measure Blood Pressure? |
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Blood pressure is measured in the form of two
numbers, namely, the systolic blood pressure and the diastolic blood
pressure. It is written as 120/80, where 120 is the systolic pressure
and 80 is the diastolic pressure.
Systolic
pressure is the pressure of the blood when the heart beats. This is
the highest pressure exerted by the blood. On the other hand,
diastolic pressure is the pressure of the blood when the heart rests
between beats. This is the lowest pressure exerted by the blood.
You
can measure your blood pressure in two different manners. That is,
using the cuff or by measuring it digitally.
The cuff is the
most common way of measuring blood pressure. It is wrapped around
your upper arm and a tube connects the cuff to a reservoir of mercury
at the bottom of a vertical glass tube. There is a rubber bulb, which
is used to blow air into the cuff. Thus pressure generated in the
cuff moves the mercury in the column. The mercury goes up with a
heart beat and comes down, when the heart is resting between the
beats.
Digitally, there are two ways of measuring blood
pressure. These are:
1) The Auscultatory method
2) The Oscillometric method
Auscultatory method
In the auscultatory method, a
stethoscope and a sphygmomanometer are used. In this method, an
inflatable cuff is placed around the upper arm, at roughly the same
vertical height as the heart. This cuff is attached to mercury. The
cuff is inflated manually by squeezing a rubber bulb repeatedly until
the artery is completely occluded.
The pressure in the cuff is
slowly reduced. When the blood starts flowing again, a whooshing or
pounding sound is heard. The pressure at this point is called
systolic pressure. Then the pressure in the cuff is further reduced,
till no sound is heard. The pressure at this point is called
diastolic blood pressure.
Both these pressures are recorded to find out
the accurate blood pressure.
Oscillometric method
Oscillometric method is similar to the auscultatory
method functionally. It is used in long-term measurement as well as
in clinical practice.
The cuff in this type
of manometer comes with an electronic pressure sensor fitted in the
cuff to detect the blood flow. In this method, the mercury manometer
is fitted on the wrist, elevated to the height of the heart, though
the upper arm is always preferred. The cuff is inflated and released
by an electrically operated pump, which then gives out a numerical
readout of the blood pressure.
Oscillometric measurement does
not require much skills and is easy to use by even non-trained staff
and by the patient themselves.
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