The wonderful thing about having a complete historic collection of blood pressure devices spanning four centuries is that you realize that there are very rarely any true inventions, as most devices are simply the "natural next step" in technology and are simply derived, or improvements of what was there before. Another thing is that every now and then some great inventions are missed just because the time was not right, or because the right team was not there behind the discovery.
Every now and then, a technology arrives that shakes the fundamentals of acquired knowledge and that opens up new horizons and doors for new ideas.
I recently re-discovered an outstanding device, which is a miracle of simplicity. It was originally designed as a calibration device for mercury blood pressure devices, but ended up being a fully fledged water-operated blood pressure monitor. It unfortunately was never explored any further by the manufacturer who after a short while relegated it to the confines of history. Just imagine if we had continued in this direction 90 years ago...
"On the third day a wedding took place at Cana in Galilee [...] and Jesus and his disciples had also been invited to the wedding. When the wine was gone, Jesus’ mother said to him, “They have no more wine.” [...] Nearby stood six stone water jars, [...] each holding from twenty to thirty gallons. Jesus said to the servants, “Fill the jars with water”; so they filled them to the brim. [...] They did so, and the master of the banquet tasted the water that had been turned into wine". John 2:1-11
Magically, Mr. Emile SPENGLER, manufacturer of the first French blood pressure monitor, performed, in his own way, the miracle of Cana, by replacing mercury with water in sphygmomanometers.
The modern art of Palpation… The Sphygmometer
History goes full circle...
To predict the future, you really have to understand the past... At the turn of the century, blood pressure measurement was an inaccurate science. We were still in the golden age of palpation.
In 1881, Samuel Siegfried Karl Ritter von Basch invented the sphygmometer. A mercury or water-filled rubber ball, connected to a manometer, was pressed against the radial artery until the pulse was obliterated. The blood pressure was then estimated using the manometer. Palpation was used to determine when the arterial pulse disappeared. So indeed, contrary to popular belief, the early devices were filled with liquid (water or mercury) and not air. It is only in 1889 that Potain, in France, improved all the compression devices by replacing water and mercury in the devices with air, substantially improving their accuracy. From this moment on, air became the compression medium of choice.
But these were aneroid devices. The standard devices still used a glass tube filled with mercury, as this made it barometrically very stable. These mercury devices are still considered to be the "gold standard" today in any clinical validation.
But one can only think of the enormous environmental and personal danger posed by these mercury filled devices, and on the other hand, of the missed opportunity for a solution to the mercury problem offered by Spengler in 1923 with the water-based sphygmomanometer.
Pity we never took it any further...
Discover the Von Basch Sphygmometer and the Spengler Water BPM on www.bloodpressurehistory.com