Blood pressure monitor
Blood pressure has long been known as an important factor in the evaluation of the general level of health of an individual. Blood pressure is the force within the arterial system of an individual that ensures the flow of blood and delivery of oxygen and nutrients to the tissue. Prolonged reduction or loss of pressure severely limits the amount of tissue perfusion and could therefore result in damage to or even death of the tissue. The blood pressure is a barometer of analysis, and it is effective for preventing of cardiovascular diseases such as cerebral apoplexy, cardiac failure and myocardial infarct to analyze the risk based on the blood pressure. When the blood flows through the brachial artery following each contraction of the heart, it imparts a pulsatile movement to the wall of the artery. This pulsatile movement is coupled to a blood pressure cuff extending over the artery as minute changes in the cuff pressure, which are known as oscillometric pulses. During and after surgery, blood pressure is a frequently monitored vital sign. Blood pressure is affected, during and after surgery, by the type of surgery and physiological factors such as the body's reaction to the surgery. Moreover, blood pressure is manipulated and controlled, during and after surgery, using various medications. Often, these physiological factors and the given medications can result in a situation of rapidly changing blood pressure requiring immediate blood pressure measurement, and corrective action. The blood pressure has intra-day fluctuating rhythm such that the blood pressure changes due to individual physical activity, reaction to a stress, reaction of cardiovascular system to behavior pattern and the like, the blood pressure drops at night time but rises before and after awakening in the morning. It is well known to use electronic blood pressure monitors for measuring the blood pressure on a patient. Various different methods may be used to measure blood pressure: invasive, oscillometric, auscultatory, tonometric, and sensor-based. The oscillometric method determines blood pressure from the amplitude of pressure oscillations in a pressurized cuff, typically measured within the cuff while the cuff is slowly deflated. The auscultatory method involves monitoring Korotkoff sounds as an inflated cuff placed around a cooperating artery of the patient slowly deflates. Systolic pressure is indicated when Korotkoff sounds begin to occur, while diastolic pressure is indicated when the Korotkoff sounds become muffled or disappear. The tonometric method typically uses an array of pressure sensitive elements which have at least one dimension smaller than the lumen of the underlying artery in which blood pressure is to be measured. The array is pressed against the site to measure a reference pressure directly from the wrist, which is correlated with arterial pressure. Automatic blood pressure monitors employing the oscillometric method measure and record the amplitude of the oscillometric pulses at a number of cuff pressures. After the blood pressure measurement had been completed, a table contains the oscillometric pulse amplitudes recorded at each cuff pressure. Automatic blood pressure monitors are commonly used to periodically measure the blood pressure of a patient. In most automatic blood pressure monitors, a pressure cuff is attached to a patient's arm over the brachial artery. Blood pressure monitors are often used not only in medical treatment facilities such as hospitals but also in the households as an apparatus for checking the physical conditions day by day. Blood pressure monitors for home use, which are being diffused now, have a function for displaying blood pressure levels with large diffusion at different times as measured values, or a function for sounding a buzzer to inform patients of a degree of risk when a value at one-time measurement exceeds a certain value. Mainly in the field of blood pressure monitors for home it is also known to measure the pressure around the wrist of the patient. This is preferred because of the easier application of the pressure cuff around the wrist as compared to the upper arm. After using a blood pressure monitor to determine one's blood pressure, users usually compare their readings to the classification published by the World Health Organisation and International Society of Hypertension. Such published materials are often included in the handbook provided with domestic blood pressure monitors.
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