Mercury Sphygmomanometer

One of the most basic and essential part of clinical practice is blood pressure measurement. A patient’s blood pressure is usually taken at every physical examination, including outpatient visits, at least daily when patients are hospitalized before and during most medial procedures. Blood pressure, sometimes referred as arterial blood pressure, is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. During each heartbeat, blood pressure differs between a maximum systolic and a minimum diastolic pressure. The pumping action of the heart mainly causes the blood pressure in the circulation. Blood pressure is recorded as two numbers, such as 120/80. The larger number indicates the

This question may pop into people’s heads who know have no prior knowledge about measure blood pressure measurement techniques. Well, typically the name of the instrument used to measure blood measure is called a sphygmomanometers. There are three types sphygmomanometers: aneroid, mercury and digital. The way mercury sphygmomanometer has not changed much over the past 5 decades, except that now it is unlikely of the device to spill mercury when dropped. Mercury sphygmomanometer is widely known to be the best there is for blood pressure measurement; however this device would most probably not be used in the near future. To date, mercury devices have largely been phased out in US hospitals, due to the concerns about the safety of mercury and not that because any more accurate devices have been developed. Currently the two alternatives for replacement of mercury are electronic (oscillometric) devices and aneroid sphygmomanometer. Due to the ban on mercury sphygmomanometer has placed new interest in alternative methods, of which aneroid devices are the leading contenders. The error rates reported with respect to accuracy of aneroid devices in older hospitals surveys range from 1% to 44%. Doctors in hospitals usually use the aneroid sphygmomanometer while the digital sphygmomanometer is typically used at

Blood pressure monitor operation is based on the oscillometric method. This method takes advantage of the pressure pulsations taken during measurements. Oscillometric measurement devices use an electronic pressure sensor with a numerical read out of blood pressure. In most cases the cuff is inflated and released by an electrically operated pump and valve, which may be fitted on the wrist (elevated to heart height), although the upper arm is preferred. Initially the cuff is inflated to a pressure in excess of the systolic arterial pressure, and then the pressure reduces to below diastolic pressure. Once the blood flow is present, but restricted, the cuff pressure will vary periodically in synchrony with the cyclic expansion and contraction of the brachial artery. The values of systolic and diastolic pressure are computed from the raw data, using an