Explain the term Blood Pressure in Technical Measurement ?
Following techniques are recommended (JNC VII):
1) Patient should be seated in a chair with their backs supported and their alms bared and supported at heart level.
2) Under special circumstance measuring BP in supine and standing positions may be indicated as in to rule out orthostatic hypotension.
3) Patient should refrain from smoking or ingesting caffeine during the 30 mm preceding the measurement.
4) Measurement should begin after at least five minutes of rest.
5 ) Appropriate cuff size must be used to ensure accurate measurement. The bladder within the cuff should encircle at least 80 percent of arm.
6) Measurement should be taken preferably with a mercury sphygmomanometer.
7) Both Systolic Blood Pressure and Diastolic Blood Pressure should be recorded. The first appearance of sound (Phase I) is used to define SBP and the disappearance of sound to define DBP.
8) Two or more readings separated by two minutes should be averaged if first two readings differ by more that five mmHg, additional readings should be obtained and average.
Guidelines of measurement : Palpatory Method: Systolic blood pressure (SBP) can be measured by gradually compressing the brachial artery while palpating the radial artery. The force required to obliterate the radial pulse represents SBP.
Ausultatory Method: The sphygmomanometer cuff is applied around the arm with its lower edge at least I inch above the antecubital space. The radial pulse is palpated while the cuff is inflated to pressure of 30 mm/Hg above the level at which radial pulsation cannot be felt. The stethoscope (diaphragm) is then placed tightly over the brachial artery and the pressure in cuff as lowered 3 mm/Hg per second until the first Korotkoff sounds occur. This is the Systolic blood pressure. Continue to lower the pressure until the sounds disappear (5th Korotkoff phase). This is the DBP.
Occasionally, the sounds may appear first (SBP) then disappear at a point below 200 mm/Hg (Silent gap) and then reappear and finally disappear (DBP). Its significance is unknown but it may be found in certain patients with hypertension.
Instrumental: Mercury sphygomenometer is still the most accurate device for clinical use; validated electronic devices or aneroid sphygmomanometer be used for home BP recording.