Sunday, September 15, 2019

How to Measure Blood Pressure? | Blood Pressure Measurement

What is Blood Pressure?
It is the pressure of circulating blood on the walls of blood vessels. Most of the pressure is due to work done by the heart by pumping blood through the circulatory system. Blood pressure generally refers to the pressure in large arteries of the systemic circulation. It is expressed in terms of the systolic pressure over diastolic pressure. It is measured in millimeters of mercury (mmHg). 
Blood pressure measurement procedure
Fig: Blood pressure measurement procedure
How to Take Blood Pressure Step by Step:
Blood pressure measurement method has discussed in the following:

Requirements:
To measure blood pressure the following instruments have to require-
  • Sphygmomanometer,
  • Stethoscope.
Method of Measuring Blood Pressure:
All the process of blood pressure measurement have explained in the below in step by step-
  • The subject should be physically and mentally relaxed, free from excitement.
  • The subject should lie down or sit comfortably. If he sites, he should place the arm on a table at the level of the heart.
  • The “zero” of the sphygmomanometer and the cuff should be at the level of the heart.
  • The arm is exposed up to the shoulder.
  • The cuff is wrapped around the upper arm just above the elbow (Middle of the cuff lies over the brachial artery).
  • The brachial artery is palpated in the cubital fossa, just medial to the tendon of the biceps brachii muscle, a little below the cuff.
  • The radial artery is palpated at the wrist by placing the middle three fingers over it.
  • The cuff is rapidly inflated by the hand pump, raising the pressure 30mmHg above the level at which the radial pulsation disappears.
  • The diaphragm of the stethoscope is placed lightly on the brachial artery and then the pressure in the cuff is gradually lowered using the release valve, keeping the earpieces of the stethoscope in the ears.
  • As the pressure is lowered slowly (2mm/sec), at a particular level in the mercury column, a tapping sound is heard. The level at which the sound is first heard is regarded as the systolic pressure.
  • The pressure in the cuff is further reduced gradually and the character of the sound changes; and finally, at a particular level the sound disappears. The level at which the sound disappears is regarded as the diastolic pressure.
  • The cuff is deflated and the procedure is repeated three times.
Observation:

Reading No.
Systole (mmHg)
Mean Systole (mmHg)
Diastole (mmHg)
Mean Diastole (mmHg)
1
115
120
80
80
2
120
80
3
125
80

Result:
Systolic blood pressure: 120mmHg,
Diastolic blood pressure: 80mmHg,
Age of the person: 24 years.

Comment:
The blood pressure of the person is within the normal physiological limit.

Precautions:
It includes-
  • The subject should be mentally and physically relaxed.
  • The size of the cuff should be proportionate to the circumference of the arm of the subject.
  • The arm, with the cuff wrapped around it, should be at the level of the heart to avoid the influence of gravity.
  • The zero levels of the mercury should be checked.
  • The cuff should not be left inflated for excess time, because the discomfort may cause generalized vasoconstriction that results in higher blood pressure.
  • The pulse rate should be checked at the same time because blood pressure is affected to some extent by the heart rate.
  • The cuff pressure should be decreased to the zero levels between the successive measurements of blood pressure.
  • While taking the reading, the eye should be at the level of the mercury column to avoid parallax.
  • If coarctation of the aorta is suspected, blood pressure should also be recorded in the thigh.