Blast From The Past: SPHYGMOMANOMETER!

The ancient Greek physician Galen first proposed the existence of blood in the human body. It was not until 1616 when William Harvey announced that Galen was wrong in his assertion that the heart constantly produced blood. Instead he proposed that there was a finite amount of blood that circulated the body in one direction only. Harvey was neither the only nor the first to question Galen's ideas. The Egyptians knew that blood flowed through the body and used leeches to unblock what they thought were passages of blood.

The first recorded instance of the measurement of blood pressure was in 1733 by the Reverend Stephen Hales. A British veterinarian, Hales spent many years recording the blood pressures of animals. Fifteen years beforehand, he took a horse and inserted a brass pipe into an artery. This brass pipe was connected to a glass tube. Hales observed the blood in the pipe rising and concluded that this must be due to a pressure in the blood. At this time the technique was invasive and highly inappropriate for clinical use.

It was not until 1847 that human blood pressure was recorded. The method used Carl Ludwig's kymograph with catheters inserted directly into the artery. The lack of a non-invasive method of determining this new idea of blood pressure lead to many physicians working in this field. Once such man, Karl Vierordt, found in 1855 that with enough pressure, the arterial pulse could be obliterated. Vierordt used an inflatable cuff around the arm to constrict the artery.

In 1881, Samuel Siegfried Karl Ritter von Basch invented the sphygmomanometer. His device consisted of a water-filled bag connected to a manometer. The manometer was used to determine the pressure required to obliterate the arterial pulse. Direct measurement of blood pressure by catheterisation confirmed that von Basch's design would allow a non-invasive method to measure blood pressure. Feeling for the pulse on the skin above the artery, was used to determine when the arterial pulse disappeared.

Scipione Riva-Rocci developed the mercury sphygmomanometer in 1896. This design was the prototype of the modern mercury sphygmomanometer. Riva-Rocci's sphygmomanometer was spotted by the American neurosurgeon Harvey Cushing while he was travelling through Italy. Seeing the potential benefit he returned to the US with the design in 1901.

This sphygmomanometer could only be used to determine the systolic blood pressure. Observing the pulse disappearance via palpitation would only allow the measuring physician to observe the point when the artery was fully constricted. Nikolai Korotkoff was the first to observe the sounds made by the constriction of the artery in 1905.

A crucial difference in Korotkoff's technique was the use of a stethoscope to listen for the sounds of blood flowing through the artery. This auscultatory method proved to be more reliable than the previous palpitation techniques and thus became the standard practice.

*So now you have a better glimpse on how your sphygmo came up, rather than just squeezing it all day long =). Expect more Blast From The Past, only here at XUSN SlakHouse - Ato ni bai!