Abnormality of blood dynamics is usually occurred in hypertension, including enhancement of reflected wave, acceleration of pulse conduction and decrease of compliance. It has been clinically proven that the central arterial pressure is a key factor of recovery from hypertension. The brachium arterial blood pressure value is determined by measurement of the peripheral arterial blood pressure by traditional or electronic manometer, usually being higher than the central arterial blood pressure, such as the ascending aortic and carotid arterial blood pressure value. Due to the different effects of different medications of blood pressure-lowering medicine on the central aortic and peripheral arterial blood pressure, using the brachium arterial systolic and diastolic blood pressure measured alone by traditional or electronic manometer to estimate the central aortic blood pressure may overestimate or underestimate the effect of blood pressure-lowering medicine on the central aortic blood pressure. Hence, it is insufficient to evaluate how well the blood pressure is controlled only by measuring of the brachium arterial blood pressure. There has been a method already which can estimate the waveform and value of ascending aortic systolic blood pressure by recording the radial arterial waveform, the brachium arterial blood pressure, and by a known mathematic formula, the related commercialized product (SphygmoCor, AtCor Medical Pty Limited) has been widely used in clinical trial, and it has been proven that the estimation of the value of ascending aortic systolic blood pressure can show the different effects on the central aortic blood pressure by different medications of blood pressure-lowering medicine. It could predict the risk of patients with cardiovascular disease after medication of different pressure-lowering medicines; hence, the measurement of the central arterial blood pressure played a role in the control of hypertension. Although SphygmoCor can estimate the ascending aortic systolic blood pressure, it needs expensive and complicated accessories and special operation techniques and is not appropriate for widely use in hospital and personal use of a patient.
Patent No. WO/1996/0390 showed an innovation of technology, employing two separated measurement parts (upper arm and wrist) to measure the brachium arterial blood pressure value (by technology of common electronic manometer) and the radial arterial blood pressure waveform (by pen-shaped arterial tonometer) respectively, and then converts the radial arterial blood pressure waveform to the ascending aortic blood pressure waveform by a known mathematic formula, and adjusts the converted ascending aortic blood pressure waveform by the measured brachium arterial blood pressure value. Users can obtain the ascending aortic blood pressure value through the converted ascending aortic blood pressure waveform, which is the commercialized, non-invasive and patented technology of estimating the waveform and value of ascending aortic blood pressure. The product of this patent, invented by an Australian scientist, Dr. Michael F. O'Rourke, needs the expensive pen-shaped pressure tonometer, a laptop, and a specialized analytic program. The pen-shaped pressure tonometer is related to the accuracy of the estimated value and needs special operation technique; therefore, the usage of the expensive diagnostic instrument is still limited to research and can not be a personal home care.