Showing posts with label history. Show all posts
Showing posts with label history. Show all posts

Monday, September 17, 2012

Invention of device for measuring blood pressure

It was William Harvey in 1616, who first described a one way circulation of blood and correctly suggested the existence of capillaries.

In 1722, Stephen Hales, an English clergyman, was the first person to measure blood pressure albeit in a horse. In 1733, he published a paper on his experiments on opening an artery in a live horse inserting a brass pipe 1/6 of an inch in diameter and attaching a vertical glass tube to this pipe.

He then allowed blood from the horse to enter the tube, and found that the blood level rose to a height of 8 ft 3 in, He also noticed that the height of the blood column rose and fell by 2-4 in with each heartbeat.

Almost 150 years later Samuel Siegfried Karl Ritter von Basch of Bavaria invented a machine that could measure the blood pressure of a human being in a non-invasive manner. It using an inflatable rubber bag filled with water. The bag was pressed over the pulse pulsation ceased and the height of the mercury column attached to the rubber bag reflected the systolic pressure.

This was the forerunner of the device introduced by Italian physician Scipione Riva-Rocci in 1896, which proved to be a prototype of the more refined instrument of today. He invented a simple device – a rubber bag that went around the arm, which was then filled with air in order to block the circulation in the brachial artery and determine at what pressure the blood was passing through.

This, along with invention of the stethoscope of Rene Laennec, helped Russian scientist NS Korotkoff in 1905 to monitor the pulse whilst the blood pressure cuff was inflated, and hence the term ‘Korotkoff sounds’.

Rene Laennec, French physician constructed the first stethoscope from a stacked paper rolled into a solid cylinder.

Although there are modern digital electronic instruments that are similar and more convenient to use, the mercury manual manometers are still considered to be gold standard as they do not need to be calibrated.

In 1978, Croslin Michael invented computerized blood pressure and pulse measuring device. His invention was the most sophisticated of its type, depending on the motion of the blood to determine its findings.
Invention of device for measuring blood pressure

Monday, July 23, 2012

Ancient history of blood circulation and blood pressure

The theories regarding blood circulation and blood pressure go far back into historical times. Since the time of the Greeks, blood was known to be the substance that sustained life.

Ancient civilizations also recognized the heart as the mechanics by which the blood was delivered to the tissues of the body.

The meaning of the Greek word arteria was ‘windpipe’. This is because in Greek physiology, the heart was the focus of respiration, as well as the center of the vascular system.

Way back in ancient Greece, Hippocrates and later Galen knew about arteries and veins. 

Aristotle (384-322 BC) a biologist as well as a philosopher considered the heart as the center of system of blood vessels, but he made no distinction between arteries and veins, and showed no sign of any knowledge of the cardiac valves.

Galen was convinced veins and arteries were not connected and blood flowed both backward and forward form the heart. Galen believed that the liver made blood from food. The newly formed blood then proceed through vein to organs.

Galen’s characterization of the blood system carried authority for fifteen hundred years.

At the beginning of the third century BC Praxagoras insisted that the arteries contain no blood but only air.
Ancient history of blood circulation and blood pressure

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