1. The Importance of Blood Pressure Measurement
The importance of accurate blood pressure determinations cannot be overemphasized. To obtain accurate blood pressure readings, the user requires
- An accurate pressure measuring instrument,
- The correct size cuff as it relates to the circumference of the limb and
- Good measurement technique.
Blood pressure is a very important vital sign; if it is high it can lead to many negative health effects including heart attack, stroke and kidney failure. About 20% of the people in the U.S. are hypertensive; many of them do not know it because there are no symptoms to identify it. Accurate blood pressure readings are critically important since erroneous readings can lead to misdiagnosis and ultimately result in treatment errors.
Accurate measurement of blood pressure relies, as it always has, on the use of a correct size cuff, good measurement technique and an instrument of known accuracy, dependability and reproducibility. We have been providing such instruments since 1916.
2. How is blood pressure measured?
TECHNIQUE OF MEASUREMENT
“In the everyday practice of medicine, a combination of the palpatory and auscultatory methods is used”.
1 - Application of the compression cuff
The blood pressure is generally recorded in the arm with the patient in a sitting or recumbent position. The physician should arrange his desk and chair or examining table so the patient’s right arm is always and inevitably presented for recording of the blood pressure. The arm should be abducted, slightly flexed, and supported by a smooth, firm surface. The artery over which the blood pressure is to be recorded should be at a level with the heart. It is not necessary for the manometer to be at heart level.<br>
The deflated compression cuff is applied evenly and snugly, but without constriction, around the right arm. The lower edge of the cuff should be 2.5 cm above the point at which the receiver of the stethoscope is to be placed.
2 - Palpatory Method
The radial or popliteal pulse is palpated and the rate and rhythm are noted. The compression cuff is then inflated to about 30 mm Hg above the pressure at which the radial pulse disappears. (When the cuff is inflated, it should not bulge nor become displaced.) The cuff is then deflated at a rate of 2 to 3 mm Hg per heartbeat. The level of pressure at which the pulse in the radial artery returns is noted and recorded as the systolic arterial blood pressure. The diastolic blood pressure is difficult to measure by palpation and is not generally determined by this method.
3 - Auscultatory Method
After the systolic blood pressure has been determined by the palpatory method, the blood pressure is then determined by auscultation over the artery at a point below the compression cuff, which has remained on the arm. The artery is first palpated, and then the receiver of the stethoscope is applied lightly but snugly over it to produce an airtight seal. The receiver must not come into contact with the patient’s clothing nor with the compression cuff. The compression cuff is then inflated rapidly to about 30 mm Hg above the systolic pressure as previously determined by the palpatory method. The cuff is then deflated at a rate of 2 to 3 mm Hg per heartbeat. While the physician is watching the meniscus of the mercury column (or the aneroid pointer), the pressure at which characteristic changes in the Korotkoff sounds occur is noted. From the changes in the quality of these sounds, the systolic and diastolic blood pressure are determined.