By MIKE MAGEE
The recent market downturn has left individuals across the globe feeling anxious. However, to ease our minds, let’s reflect on a historical narrative of collaboration and achievement in the medical field.
A medical student typically acquires around 15,000 new terms throughout their four years of education. Among these is the term sphygmomanometer, which refers to a device used for measuring blood pressure. this term originates from the Greek word σφυγμός (sphygmos) meaning “pulse,” combined with the scientific term manometer (from French manomètre).
While aspiring doctors quickly memorize terminology and learn to utilize various instruments essential for their profession, few grasp the extensive historical journey filled with incremental advancements and engineering breakthroughs that have led to these innovations.
The name William Harvey is well-known among students; he was able to infer that blood circulates through a four-chambered heart via a “double circulation system” directed first towards the lungs and then back through a “closed system” before reaching other organs. In 1628, he published his findings in an influential work titled De Motu Cordis.
A lesser-known figure is Stephen Hales, who at age 56 made significant contributions by introducing the concept of “blood pressure” in 1733. A century later, German physiologist Johannes Müller would assert that Hales’ discovery was even more pivotal than Harvey’s revelation about blood itself.
In a report from 2014, The joint National Committee on Prevention, Detection, Evaluation, and treatment of High Blood pressure highlighted that every increase of 20 mm Hg in systolic or 10 mm Hg in diastolic blood pressure doubles mortality risk from ischemic heart disease and stroke.
This comparison should not undermine Harvey’s achievements; he accurately estimated human blood volume (around ten pints or five liters), calculated heart contractions per minute along with ejected blood volume per beat while recognizing continuous recirculation—all accomplished over four centuries ago. However, understanding how to measure this function and link it to critical health conditions like hypertension required two centuries of international scientific collaboration.
Born in 1578 and passing away in 1657—twenty years prior to Stephen Hales—harvey laid foundational knowledge for future scientists. Hales was an English clergyman whose intense curiosity about natural sciences often drew mockery from contemporaries like scholar Thomas Twinning who humorously critiqued him through poetry titled “The Boat of Hales.”
“Green Teddington’s serene retreat
For Philosophic studies meet,
Where good Pastor Stephen Hales
Weighed moisture in scales,
To lingering death put Mares and Dogs,
And stripped living Frogs’ skins,
Nature he loved; her works intent
To search or sometimes torment.”
This last line may hold some truth considering Hales’ own account detailing his groundbreaking measurement of arterial blood pressure:
“In December I caused a mare to be tied down alive on her back… I inserted into it a brass pipe whose bore was one sixth inch… The blood rose nine feet above my left ventricle… when at full height it would rise or fall after each pulse by several inches.”
This marked humanity’s first acknowledgment of “blood pressure,” yet nearly another hundred years would pass before reliable measurement tools became available thanks largely due to French physician-physicist Jean Léonard Marie Poiseuille.. Born amidst revolutionary upheaval in France during1799 ,his dissertation presented innovative use mercury manometers attached anticoagulant-laced cannulas within lab animals yielding reproducible arterial readings earning him accolades from Royal Academy Medicine .
However direct arterial puncture proved impractical invasive By1955 scientists surmised applying external counter-pressure artery could obliterate pulse below obstruction measuring generated obstructing external rubber ball essentially revealed systolic pressure generated contracting heart.< / P >
In1881 Austrian physician namedKarl Samuel ritter von Basch created elaborate portable machine including manometer capable measuring internal water-pressure inside inflatable rubber ball applied wrist radial artery peak necesary eliminate pulse below roughly peak column-blood when contracted eight years later French physicianPierre Carle Édouard Potain replaced water air compression.< / A >
By1896 appreciation grew regarding flow series waves peaking contraction falling relaxation replacing wrist compressing cup air-filled cuff wrapped upper arm constricting larger brachial artery Russian surgeon N.C.Korotkoff suggested doctors listen waves rather than feel pulse sounds described became known asKorotkoff sounds.< / A >
Korotkoff wrote based observation speaker came conclusion perfectly constricted artery under normal conditions emits no sounds sleeve put middle third arm rapidly rises until circulation below stops fully initially no sounds whatsoever as mercury drops certain height appears first short faint tones indicating part-pulse wave passed sleeve finally all disappear time disappearance indicates free passage flow consequently reading corresponds minimum diastolic-blood-pressure.< / EM >
Mike Magee MD Medical Historian regular contributor THCB author CODE BLUE Inside America’s Medical Industrial Complex.(Grove/2020)