MEASUREMENT OF HUMAM BLOOD PRESSURE
Materials required: Sphygmomanometer, Stethoscope
Theory
Blood pressure is the force of blood against the walls of the arteries. Blood
pressure is recorded as two numbers, the systolic pressure (the pressure
when the heart beats) over the diastolic pressure (the pressure when the
heart relaxes between beats).
Blood pressure is measured by the use of a device known as a
sphygmomanometer. This device consists of an inflatable cuff connected
by rubber hoses to a hand pump and to a pressure gauge graduated in
millimeters of mercury. The cuff is wrapped around the upper arm and
inflated to a pressure that will shut off the brachial artery. The examiner
listens to the sounds of the brachial artery by placing the bell of a
stethoscope in the inside of the elbow below the biceps; the pressure of
the cuff is allowed to fall gradually by opening a screw valve located next
to the hand pump. The examiner then listens for the sounds of Korotkoff.
The sounds are divided into five phases based on the loudness and quality
of the sounds.
Phase 1. A loud, clear tapping sound is evident that increases in intensity
as the cuff is deflated.
Phase 2. A succession of murmurs can be heard. Sometimes the sounds
seem to disappear during this time, which may be a result of inflating or
deflating the cuff too slowly.
Phase 3. A loud, thumping sound similar to Phase 1 but less clear,
replaces the murmur.
Phase 4. A muffled sound abruptly replaces the thumping sounds of
Phase 3.
Phase 5. No sound.
The cuff pressure at which the first sound is heard (that is, the beginning
of Phase 1) is taken as the systolic pressure. The cuff pressure at which
the sound becomes muffled (the beginning of Phase 4) and the pressure
at which the sound disappears (the beginning of Phase 5) are taken as
measurements of the diastolic pressure. Systolic pressure is written first
and the diastolic pressure, e.g., 120/80.
Value of BP
= 120/80 – Normal
> 140/90 – Hypertension
< 90/60 – Hypotension
Method
1. Work in pairs. Those who are to have their blood pressure measured
should be seated with their sleeves rolled up.
2. Attach the cuff of the sphygmomanometer snugly around the upper
arm.
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3. Place the stethoscope directly below the cuff in the well of the elbow
joint.
4. Close the valve of the bulb by turning it clockwise. Pump air into the
cuff until the pressure gauge goes to 180 mm Hg.
5. Turn the valve of the bulb counterclockwise and slowly release air from
the cuff. Listen for a pulse.
6. When you first hear the sounds of Korotkoff, note the pressure on the
gauge. This is the systolic pressure. (As the cuff is inflated, the brachial
artery in the arm collapses. When the pressure is released, the artery
expands and you hear a pulse. As more pressure on the artery is
released, all sound ceases.)
7. Continue to listen until the clear thumping sound of the pulse becomes
strong and then fades. When you hear the full heartbeat, note the
pressure. This is the diastolic pressure.
8. Record the systolic and diastolic measurement in the record sheet.
Observation
Table 1. Measurement of BP of class 12 students of Oxbridge
International College
Remarks
BP (Normal/Hypertension
S.No Name of student
(systolic/diastolic) /
Hypotension)
Conclusion
The measurement of BP of class 12 students was done and the BP of
maximum number of students (…………) was found to be normal,
…………… students were found to have high BP and ……………. students
were found to have low BP.
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