2. Why is knowing blood pressure important?
The SCENIHR opinion states:
Blood Pressure Measurements
Raised blood pressure throughout its range is the most significant cause of death and disability in the world (Lopez et al. 2006). Accurate blood pressure measurement is therefore vital in the prevention and treatment of blood-pressure–related diseases. Additionally, in very ill patients, accurate measurement of blood pressure is essential for monitoring cardiovascular homeostasis.
For more than a century, blood pressure has been measured worldwide both in clinical practice and medical research by auscultation using the mercury sphygmomanometer. Riva–Rocci described this indirect measurement of the blood pressure as the outside pressure needed to occlude the brachial artery (Riva-Rocci 1896). This was achieved by wrapping an inflatable bladder encased in a non distensible cuff, around the arm or leg and inflating it until the pressure on the cuff is greater than the blood pressure in the artery, and the artery is occluded. The cuff is then slowly deflated until the palpable pressure reappears through the partially compressed artery. The level of pressure on the bladder which is reflected on the manometer at the time the first repetitive sound is heard, is the maximum pressure generated during each cardiac cycle. This is defined as systolic blood pressure. The diastolic blood pressure is the level of pressure at which sounds disappear completely when the artery is not compressed and blood flow is restored. In 1905 Korotkov described the auscultatory method; this is the observation of the repetitive sounds generated by the blood flow (Korotkov 1905). As the cuff pressure reduces gradually during the deflation the Korotkov sound changes in intensity and quality, and five different stages can be distinguished (Korotkov 1905).
The indirect blood pressure measurement with mercury sphygmomanometers has been shown to be valuable in several clinical circumstances. Their extensive use has allowed the collection of the necessary evidence to identify arterial hypertension as a major risk factor for cardiovascular diseases. Most epidemiological and clinical data on hypertension as a cardio-vascular risk factor have been obtained by this blood pressure measuring device. Based on this relation to clinical disease and long-lasting experience, blood pressure measurement using the mercury sphygmomanometer currently is regarded as the gold standard method for indirect measurement of blood pressure.