Measurment Of Blood Pressure In Man

Lab. no. 13:

Measurment of Blood Pressure in Man [email protected]

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Measurment of BP indirectly: In man, indirect method is usually employed by Sphygmomanometer. This is of three types: 1. Ordinary mercury sphygmomanometer. 2. Electronic sphygmomanometer. 3. Aneroid sphygmomanometer.

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The Sphygmomanometer: It consists of a rubber bag connected to a manometer. The rubber bag can be inflated by a bulb attached to it. A valve is provided near the bulb to allow the release of air from the bag. The rubber bag is enclosed in a cloth cuff. Note that in the manometer scale, one small division represents (2 mm. Hg). [email protected]

Procedure: Allow the subject to relax for 5 min. Expose the upper arm and wrap the cuff around it so that the lower edge of the cuff is at least 2.5 cm above the elbow.

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The palpatory method: Feel the radial pulse with the left hand and with the right hand raise the pressure in the sphygmomanometer till the pulse disappears. Raise the pressure 20 mm further. Now lower the pressure slowly by slightly opening the release valve and take the reading on the manometer when the pulse is just palpable. [email protected]

The palpatory method: (cont.) This is the reading of systolic blood pressure (SBP). Diastolic blood pressure (DBP) cannot be recorded by this method. SBP recorded by this method is 5–10 mm Hg. less than that recorded by the auscultatory method.

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The auscultatory method: Palpate the brachial artery over the elbow and place the chest- piece of the stethoscope over it firmly but without undue pressure. The chest-piece should not rub against the cuff or the tubing of the sphygmomanometer.

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The auscultatory method: (cont.) Raise the pressure to the top of the mercury manometer, or if palpatory method has been used, to 30 mm above the SBP by that method. No sounds would be heard in the stethoscope. Release the pressure so that mercury falls at a uniform rate of 2–3 mm/sec. Note the level when Korotkoff sounds begin to be heard for the first time. [email protected]

The auscultatory method: (cont.) These are faint tapping sounds that coincide with the frequency of the heart beats. This level is SBP. Lower the pressure further and take the reading when the sounds become muffled. This is DBP. If the pressure is lowered 5–10 mm further, the sounds disappear completely. Now release the pressure all at once. [email protected]

The auscultatory method: (cont.) For the beginners it may be difficult to appreciate when the sounds become muffled, hence the level at which the sounds disappear may be taken as the DBP. The whole procedure should not be unduly prolonged since prolonged obstruction to the blood flow in the limb produces a rise of blood pressure all over the body. [email protected]

Korotkoff sounds: Are thought to be due to the blood jetting through the partly occluded vessel, the jet causes turbulence of the blood flow in the open vessel beyond the cuff and this sets up the vibrations heard through the stethoscope.

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Normal Blood Pressure values: -In healthy adults: SBP = 100 –140 mm Hg. DBP = 60 –90 mm Hg. -In children it approximates to the lower figure in each case (100 SBP/60 DBP) mm Hg. -In the elderly it reaches or even exceeds the higher figures (140 SBP/90 DBP) mm Hg. -The difference between SBP and DBP is pulse pressure (= 30–60 mm Hg). [email protected]

pulse pressure: =The difference between SBP and DBP. Normal pulse pressure= pressure

30–60 mm Hg.

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