DETERMINATION OF ARTERIAL BLOOD PRESSURE IN MAN

 

DETERMINATION OF ARTERIAL BLOOD PRESSURE IN MAN

 

Aim: To determine the arterial blood pressure in man by indirect method before and after exerciser.

 

Principle: It consists of balancing air pressure against the pressure of blood in the bronchial artery and then estimating the former by means of a mercury manometer.

 

Apparatus: Sphygmo manometer and stethoscope are the instruments which are universally accepted and used to determine the arterial blood pressure by indirect or clinical method. Essentially it consists of an inflatable, Cloth -covered flat rubber bag nearly by wrapping and extension for the cloth covering over the bag and around the arm like a bandage. It is usually referred to as cuff. On one side the cavity of the rubber bag is connected to manometer and on the other side it is connected to a pressure bulb pump by means of rubber tubes.

                By using the pressure bulb, the rubber bag can be inflated to any desired pressure on the tube leading from the bulb to the bag, there is a needle valve which can be opened gradually to allow the air to escape, there by reducing the pressure in the bag as required.

                The manometer consists of a wide glass bulb bottom and a vertical glass tube. The glass bulb is filled with mercury and is connected with the inflatable cuff. The column of mercury in the bulb rises or falls in the glass tube depending upon the inflation or deflation of the cuff. The vertical glass tube on either side, is celebrated each division indicating 2 mm of. Pressure can be increased upto 300 mm Hg. from 0 mm Hg.

 

Position of the Patient: Depending upon the condition of the patient, he can be kept in lying position (supine position on). If he is able to sit, he can sit in ‘a chair what ever may by the position of the patient, the hand must be kept at the heart level and the manometer must be kept at the heart level upper arm of the patient must be bare up to the shoulder.

 

Procedure: The uninflated cuff is wrapped around the upper arm neither to tight nor too loosely. The cubital fosses must be left free the subject is advised, to relax the arm muscles: after ‘setting every thing as said above the determination of Blood pressure is stated.

 

Method to determine blood pressure: There are different methods to determine the blood pressure.

1. Palpatory method
2. Auscultory method
3. Oscillartory method

                Among these, oscillatory method is out of date due to its inaccuracy. Palpators method is to determine only systolic blood pressure but not the diastolic, blood pressure. But the auscitatory method is the one by which both can be determined and also with accuracy.

 

Palpatory Method: With the cuff wrapped around, the upped arm, the pulse is palpated first by feeling the radial pulse the cuff is inflated to increase the air pressure till it over comes the blood pressure and obliterates the arterial lumen so that the pulses no longer felt. The pressure must be raised another 20 mm Hg beyond this level.

                By means of the valve, the air is allowed to escape very gradually so that the air pressure falls inside the cuff and the mercury column in the manometer comes down simultaneously at the same time the pulse also must be examined as the air pressure falls a point reaches where the pulse appears suddenly, This is the point where the air pressure and the blood pressure are equal and the pulse appears. That is known as the systolic pressure, once pulse appears it will remain as it is. So the diastoic pressure can not be measured by this.

 

Auscultatory method: Here to auscultate the sounds, the stethoscope is used. The branchial artery is palpated and the place is noted in the cubital fossa to keep the chests piece of stethoscope.

                The air pressure is raised in the Sphygmomnometer to 20 to 30 mm Hg above the systolic pressure as determined by palpatory method. Now the air pressure must be slowly reduced and simultaneously the chest piece of the stethoscope is kept on the cubital fossa to hear any sounds, it appear.

 

                As we reduce the compression 3 sounds are heard which finally disappears. Those sounds appears during determination of blood pressure are known so korot koff sounds.

 

                First sound- sudden appearance of a clear, tapping sound which corresponds with the systole of the heart and corresponds with systolic pressure, Second sound with further failing the air pressure. The sound attains harsh murmurish quality.

 

                Third sound with still further reduction in the air pressure, the sound become clearer, louder and gonging type.

 

                Then finally, with still further reduction in. the air pressure, the sound become muffled and finally disappears. The appearance of the first sound .is systolic pressure and the disappearance of the sound is the diastolic pressure.

 

Normal average values:

                Systolic B. P. 120. 120+20 nim. Hg

                Diastolic B. P. 75 + 15 mm. Hg.

 

N.B: The systolic and diastolic pressure are conventionally written as 120/80 or 130/90 etc.

 

Precaution: 1) Observe the arterial pressure only after the subject has been assured and when he is quietly resting free from excitement and with the arm relaxed. This is relevant, for the arterial pressure show temporary variations with change of posture after meals, in excitement etc.

 

2) Reject the first reading in nervous subject, for it is often too high. A second reading will more closely represent the true pressure.

 

3) When successive estimation to be made the air pressure in the armlet should be allowed to fall to zero as soon as each reading has been taken. The work should be quiet and quick.

 

4) Repeated compression and decompression of the armlet just before making actual V determination of arterial blood pressure will remove any spasm of the arterial wall and eliminate the source of in accuracy.