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A sphygmomanometer ( ), blood pressure meter, blood pressure monitor or blood pressure gauge (also referred to as a sphygmometer〔As the etymology indicates, this should have the somewhat different connotation of 'a gauge to measure pulse', whereas the main function is actually to measure pressure.〕) is a device used to measure blood pressure, composed of an inflatable cuff to collapse and then release the artery under the cuff in a controlled manner,〔 and a mercury or mechanical manometer to measure the pressure. It is always used in conjunction with a means to determine at what pressure blood flow is just starting, and at what pressure it is unimpeded. Manual sphygmomanometers are used in conjunction with a stethoscope. The word comes from the Greek σφυγμός (''sphygmos'', pulse), plus the scientific term manometer (pressure meter). The device was invented by Samuel Siegfried Karl Ritter von Basch in 1881. Scipione Riva-Rocci introduced a more easily used version in 1896. In 1901, Harvey Cushing modernized the device and popularized it within the medical community. A sphygmomanometer consists of an inflatable cuff, a measuring unit (the mercury manometer, or aneroid gauge), and a mechanism for inflation which may be a manually operated bulb and valve or a pump operated electrically. The usual unit of measurement of blood pressure is millimeters of mercury (mmHg) as measured directly by a manual sphygmomanometer. == Types == There are two types of sphygmomanometers: * Manual sphygmomanometers require a stethoscope for auscultation (see below). They are used by trained practitioners. It is possible to obtain a basic reading through palpation alone, but this only yields the systolic pressure. * * Mercury sphygmomanometers are considered to be the gold standard. They measure blood pressure by observing the height of a column of mercury, which do not require recalibration. Due to their accuracy, they are often required in clinical trials of pharmaceuticals and for clinical evaluations of determining blood pressure for high-risk patients including pregnant women. * * Aneroid sphygmomanometers (mechanical types with a dial) are in common use; they may require calibration checks, unlike mercury manometers. Aneroid sphygmomanometers are considered safer than mercury based, although inexpensive ones are less accurate. A major cause of departure from calibration is mechanical jarring. Aneroids mounted on walls or stands are not susceptible to this particular problem. * Digital, using oscillometric measurements and electronic calculations rather than auscultation. They may use manual or automatic inflation. These are electronic, easy to operate without training, and can be used in noisy environments; they are not as accurate as mercury instruments. They measure systolic and diastolic pressures by oscillometric detection, using a piezoelectric pressure sensor and electronic components including a microprocessor.〔(Oscillometry, Explanation of oscillometric detection in Medical Electronics, N Townsend, p48-51 )〕 They do not measure systolic and diastolic pressures directly, ''per se'', but calculate them from the mean pressure and empirical statistical oscillometric parameters. Calibration is also a concern for these instruments.〔Can we trust automatic sphygmomanometer validations? Turner MJ. Journal of Hypertension. 28(12), December 2010, pp. 2353–2356 doi: 10.1097/HJH.0b013e32833e1011.〕〔Automated Sphygmomanometers Should Not Replace Manual Ones, Based on Current Evidence Martin J. Turner and Johan M. van Schalkwyk American Journal of Hypertension. 21(8), p. 845.〕〔Sphygmomanometer calibration--why, how and how often? Turner MJ1, Speechly C, Bignell N. Australian Family Physician. October 2007; 36(10):834-838.〕 Most instruments also display pulse rate. Digital oscillometric monitors are also confronted with several "special conditions" for which they are not designed to be used, such as: arteriosclerosis; arrhythmia; preeclampsia; ''pulsus alternans''; and ''pulsus paradoxus''. Such people should use analog sphygmomanometers, as they are more accurate when used by a trained person. Digital instruments may use a cuff placed, in order of accuracy〔(Inaccuracy of wrist-cuff oscillometric blood pressure devices: an arm position artefact? Adnan Mourad, Alastair Gillies, Shane Carney, Clinical methods and pathophysiology )〕 and inverse order of portability and convenience, around the upper arm, the wrist, or a finger. The oscillometric method of detection used gives blood pressure readings that differ from those determined by auscultation, and vary subject to many factors, for example pulse pressure, heart rate and arterial stiffness.〔(Oscillometric blood pressure measurement: progress and problems. van Montfrans, Blood Press Monit. 2001 Dec;6(6):287-90 )〕 Some instruments claim also to measure arterial stiffness. However such machines are not recommended for regular users as machines that claim to have 3% accuracy rate, are usually inaccurate to over 7%, and even provided two different readings when checked at the same time. Some of these monitors also detect irregular heartbeats. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Sphygmomanometer」の詳細全文を読む スポンサード リンク
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