Sphygmomanometer

The word sphygmomanometer uses the combining form of sphygmo- + manometer. The roots involved are as follows: Greek {{lang|el|σφυγμός}} sphygmos "pulse", plus the scientific term manometer (from French manomètre), i.e. "pressure meter", itself coined from {{lang|el|μανός}} manos "thin, sparse", and {{lang|el|μέτρον}} metron "measure".{{OEtymD|sphygmomanometer}}{{OEtymD|manometer}}{{LSJ|sfugmo/s|σφυγμός}}, {{LSJ|mano/s|μανός}}, {{LSJ|me/tron|μέτρον|ref}}.

Most sphygmomanometers were mechanical gauges with dial faces, or mercury columns, during most of the 20th century. Since the advent of electronic medical devices, names such as "meter" and "monitor" can also apply, as devices can automatically monitor blood pressure on an ongoing basis.

File:Sphygmomanometer WWI Memorial de Verdun.JPG]]

The sphygmomanometer was invented by Samuel Siegfried Karl Ritter von Basch in the year 1881.{{cite journal|title=A short history of blood pressure measurement|journal=Proceedings of the Royal Society of Medicine|year=1977|first=J|last=Booth|volume=70|issue=11|pages=793–9|pmid=341169 |pmc=1543468|doi=10.1177/003591577707001112 }} Scipione Riva-Rocci introduced a more easily-usable version in 1896. In 1901, pioneering neurosurgeon Dr. Harvey Cushing brought an example of Riva-Rocci's device to the US, modernized and popularized it within the medical community. Further improvement came in 1905 when Russian physician Nikolai Korotkov included diastolic blood pressure measurement following his discovery of "Korotkoff sounds". William A. Baum invented the Baumanometer brand in 1916,[https://patents.google.com/patent/US1594039A/ U.S patent 1594039 Manometer] while working for The Life Extension Institute which performed insurance and employment physicals.

Both manual and digital meters are currently employed, with different trade-offs in accuracy versus convenience.

File:2020 Sfigmomanometr elektroniczny.jpg|BP 138/73 mmHg as result on electronic sphygmomanometer

File:Sphygmomanometer&Cuff.JPG|Aneroid sphygmomanometer with an adult cuff

File:Sphygmomanometer.JPG|Aneroid sphygmomanometer dial, bulb, and air valve

File:Clinical Mercury Manometer.jpg|Clinical mercury manometer

File:Advanced Digital Sphygmomanometer.jpg|Clinical WelchAllyn sphygmomanometer

A stethoscope is required for auscultation (see below). Manual meters are best used by trained practitioners, and, while it is possible to obtain a basic reading through palpation alone, this yields only the systolic pressure.

• Mercury sphygmomanometers are considered the gold standard. They indicate pressure with a column of mercury, which does not require recalibration.{{cite web|title=Comparing Mercury and Aneroid Sphygmomanometers|url=http://www.sustainablehospitals.org/HTMLSrc/IP_Merc_Tools_CompSphyg.html|website=Sustainable Hospitals / Lowell Center for Sustainable Production|access-date=23 February 2015|date=2003}} Because of their accuracy, they are often used in clinical trials of drugs and in clinical evaluations of high-risk patients, including pregnant women. A frequently used wall mounted mercury sphygmomanometer is also known as a Baumanometer.{{cite web|url=https://www.nytimes.com/2005/03/27/nyregion/turning-mercury-into-solid-gold.html|title=Turning Mercury Into Solid Gold |website=The New York Times |date=27 March 2005 |access-date=5 July 2018}}
• 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 sphygmomanometers, although inexpensive ones are less accurate.{{cite news|last=Misrin|first=J|title=Aneroid Sphygmomanometer: A Battle for Safer Blood Pressure Apparatus|url=http://www.sphygmomanometerhq.com/aneroid-sphygmomanometer-battle-for-safer-blood-pressure-apparatus/|access-date=27 February 2012|archive-date=10 August 2015|archive-url=https://web.archive.org/web/20150810185015/http://sphygmomanometerhq.com/aneroid-sphygmomanometer-battle-for-safer-blood-pressure-apparatus/|url-status=dead}} A major cause of departure from calibration is mechanical jarring. Aneroids mounted on walls or stands are not susceptible to this particular problem.

Digital meters employ oscillometric measurements and electronic calculations rather than auscultation. They may use manual or automatic inflation, but both types are electronic, easy to operate without training, and can be used in noisy environments. They calculate systolic and diastolic pressures by oscillometric detection, employing either deformable membranes that are measured using differential capacitance, or differential piezoresistance, and they include a microprocessor.{{Cite web |url=http://www.geriatria.unimo.it/PDF/IPERTENSIONE/Oscillometry.pdf |title=Oscillometry, Explanation of oscillometric detection in Medical Electronics, N Townsend, p48-51 |access-date=10 February 2013 |archive-date=22 May 2013 |archive-url=https://web.archive.org/web/20130522042033/http://www.geriatria.unimo.it/PDF/IPERTENSIONE/Oscillometry.pdf |url-status=dead }} They estimate mean arterial blood pressure and measure pulse rate; while systolic and diastolic pressures are obtained less accurately than with manual meters,{{Cite web|url=http://www.severehypertension.net/hbp/more/oscillometric-method/|title=Oscillometric Method - Methods of Blood Pressure Measurement - Measurement of Blood PressureMethods of Blood Pressure Measurement -|website=www.severehypertension.net|date=22 December 2007|access-date=13 April 2017}} and calibration is also a concern.Turner MJ. "Can we trust automatic sphygmomanometer validations?" Journal of Hypertension. 28(12), December 2010, pp. 2353–2356. {{doi|10.1097/HJH.0b013e32833e1011}}.{{cite journal | last1=Turner | first1=M. J. | last2=van Schalkwyk | first2=J. M. | title=Automated Sphygmomanometers Should Not Replace Manual Ones, Based on Current Evidence | journal=American Journal of Hypertension | publisher=Oxford University Press (OUP) | volume=21 | issue=8 | date=1 August 2008 | issn=0895-7061 | doi=10.1038/ajh.2008.204 | pages=845| doi-access=free | pmid=18648356 }}Turner MJ1, Speechly C, Bignell N. (October 2007). "Sphygmomanometer calibration—why, how and how often?" Australian Family Physician. 36(10):834-838. Digital oscillometric monitors may not be advisable for some patients, such as those with arteriosclerosis, arrhythmia, preeclampsia, pulsus alternans, and pulsus paradoxus, as their calculations may not be correct for these conditions,{{cite journal |vauthors=Hamzaoui O, Monnet X, Teboul JL |title=Pulsus paradoxus |journal=Eur. Respir. J. |volume=42 |issue=6 |pages=1696–705 |year=2013 |pmid=23222878 |doi=10.1183/09031936.00138912 |doi-access=free }}{{cite journal |vauthors=O'Brien E, Asmar R, Beilin L, Imai Y, Mallion JM, Mancia G, Mengden T, Myers M, Padfield P, Palatini P, Parati G, Pickering T, Redon J, Staessen J, Stergiou G, Verdecchia P |title=European Society of Hypertension recommendations for conventional, ambulatory and home blood pressure measurement |journal=J. Hypertens. |volume=21 |issue=5 |pages=821–48 |year=2003 |pmid=12714851 |doi= 10.1097/00004872-200305000-00001|s2cid=3952069 |url=https://lirias.kuleuven.be/handle/123456789/24165 }} and in these cases, an analog sphygmomanometer is preferable when used by a trained person.

Digital instruments may use a cuff placed, in order of accuracy{{cite journal | url = http://www.dableducational.org/pdfs/september05/051-05_Wrist_device_inaccuracy_JBP_Monit_May2005.pdf | title = Inaccuracy of wrist-cuff oscillometric blood pressure devices: an arm position artefact? | first1 = Adnan | last1 = Mourad | first2 = Alastair | last2 = Gillies | first3 = Shane | last3 = Carney | journal = Clinical Methods and Pathophysiology | pmid = 15812253 | doi = 10.1097/00126097-200504000-00003 | date = 2005 | volume = 10 | issue = 2 | pages = 67–71| s2cid = 6100566 }} and inverse order of portability and convenience, around the upper arm, the wrist, or a finger.{{cite web|title=Blutdruckmessgerät - Handgelenk - Blutdruckmessgerät - Test|url=http://blutdruckmessgeraet-vergleich-test.de/blutdruckmessgeraet-handgelenk/|publisher=Blutdruckmessgeraet-vergleich-test.de|access-date=27 September 2016|language=de-DE}} Recently, a group of researchers at Michigan State University developed a smartphone based device that uses oscillometry to estimate blood pressure.{{Cite journal|last=Chandrasekhar|first=Anand|date=7 March 2018|title=Smartphone-based blood pressure monitoring via the oscillometric finger-pressing method|journal=Science Translational Medicine|language=en|volume=10|issue=431|pages=eaap8674|doi=10.1126/scitranslmed.aap8674|pmid=29515001|pmc=6039119}}{{Cite journal|last=Chandrasekhar|first=Anand|date=3 September 2018|title=An iPhone Application for Blood Pressure Monitoring via the Oscillometric Finger Pressing Method|journal=Scientific Reports|language=en|volume=8|issue=1|pages=13136|doi=10.1038/s41598-018-31632-x|pmid=30177793|pmc=6120863|bibcode=2018NatSR...813136C}} The oscillometric method of detection used gives blood pressure readings that differ from those determined by auscultation, and vary according to many factors, such as pulse pressure, heart rate and arterial stiffness,{{cite journal | pmid = 12055403 | volume=6 | issue=6 | title=Oscillometric blood pressure measurement: progress and problems | author=van Montfrans GA | journal=Blood Press Monit | pages=287–90| year=2001 | doi=10.1097/00126097-200112000-00004 }} although some instruments are claimed also to measure arterial stiffness, and some can detect irregular heartbeats.

File:MMSA Checking Blood Pressure.JPG

File:Korotkow English.jpg

In humans, the cuff is normally placed smoothly and snugly around an upper arm, at roughly the same vertical height as the heart while the subject is seated with the arm supported. Other sites of placement depend on species and may include the flipper or tail. It is essential that the correct size of cuff is selected for the patient. Too small a cuff results in too high a pressure, while too large a cuff results in too low a pressure. For clinical measurements it is usual to measure and record both arms in the initial consultation to determine if the pressure is significantly higher in one arm than the other. A difference of 10 mmHg may be a sign of coarctation of the aorta. If the arms read differently, the higher reading arm would be used for later readings.{{cite journal|title=Accurate Blood Pressure Measurements and the Other Arm|year=2013|pmc=3709227|last1=Fred|first1=H. L.|journal=Texas Heart Institute Journal|volume=40|issue=3|pages=217–219|pmid=23914007}} The cuff is inflated until the artery is completely occluded.

{{anchor|A stethoscope is required for auscultation (see below)}}

With a manual instrument, listening with a stethoscope to the brachial artery, the examiner slowly releases the pressure in the cuff at a rate of approximately 2 mmHg per heart beat. As the pressure in the cuffs falls, a "whooshing" or pounding sound is heard (see Korotkoff sounds) when blood flow first starts again in the artery. The pressure at which this sound began is noted and recorded as the systolic blood pressure. The cuff pressure is further released until the sound can no longer be heard. This is recorded as the diastolic blood pressure. In noisy environments where auscultation is impossible (such as the scenes often encountered in emergency medicine), systolic blood pressure alone may be read by releasing the pressure until a radial pulse is palpated (felt). In veterinary medicine, auscultation is rarely of use, and palpation or visualization of pulse distal to the sphygmomanometer is used to detect systolic pressure.

Digital instruments use a cuff which may be placed, according to the instrument, around the upper arm, wrist, or a finger, in all cases elevated to the same height as the heart. They inflate the cuff and gradually reduce the pressure in the same way as a manual meter, and measure blood pressures by the oscillometric method.

{{Main|Blood pressure}}

By observing the mercury in the column, or the aneroid gauge pointer, while releasing the air pressure with a control valve, the operator notes the values of the blood pressure in mmHg. The peak pressure in the arteries during the cardiac cycle is the systolic pressure, and the lowest pressure (at the resting phase of the cardiac cycle) is the diastolic pressure. A stethoscope, applied lightly over the artery being measured, is used in the auscultatory method. Systolic pressure (first phase) is identified with the first of the continuous Korotkoff sounds. Diastolic pressure is identified at the moment the Korotkoff sounds disappear (fifth phase).

Measurement of the blood pressure is carried out in the diagnosis and treatment of hypertension (high blood pressure), and in many other healthcare scenarios.

• {{Portal inline|Medical}}
• Critical closing pressure

{{Reflist}}

{{Commons category|Sphygmomanometers}}

• {{US patent reference |number = 1089122 |inventor = Francis Ashley Faught, Charles J Pilling |title = Apparatus for measuring and indicating blood-pressure|y = 1914 |m = 03 |d = 03 }}
• {{US patent reference |number = 1594039 |inventor = William A Baum |title = Manometer |y = 1926|m = 07|d = 27 }}
• {{US patent reference |number = 2560237 |inventor = R. H. Miller |title = Sphygmomanometer |y = 1951|m = 07|d = 10 }}
• {{US patent reference |number = 6752764 |inventor = Man S. Oh |title = Pocket sphygmomanometer |y = 2004|m = 06|d = 22 }}

Category:1881 introductions

Category:19th-century inventions

Category:Austrian inventions

Category:Blood pressure

Category:Medical equipment

Category:Physiological instruments

Category:Pressure gauges