It Took Thousands of Years of Theory Plus 200 Years of MedTech to Build the Sphygmomanometer
According to the Australian Institute of Health and Welfare (AIHW), 32 percent of Australia’s adult population suffers from high blood pressure. Of those Australians, one in three takes medication. The other two suffer uncontrolled blood pressure.
That’s heaps of pressure on one island. Since we can’t tap that pressure as a source of renewable energy (could we call it that?) medical professionals have to continue to try to educate Australians about the imminent dangers of untreated high blood pressure. We’ve come too far since ancient humans to do nothing about it.
While theories existed thousands of years beforehand, it’s only been in the last several hundred years humans have had the ability to measure blood pressure. Just in time too.
The longer humans live on Earth, the more valuable we find this information. Blood pressure is one of the single most important indicators of one’s health.Measuring it has been the great work of a few notable researchers.
Hales wasn’t the first to talk about blood pressure. The ancient Chinese and Greeks theorized how the circulatory system worked. Only, they couldn’t prove any of it.
In 1733, Stephen Hales found a way to prove the existence of blood pressure, albeit via a crude methodology. Using a horse, because what human would subject herself to this, Hales inserted a glass pipe into the horse’s artery.
There, one could observe the pressure of the blood in the tube as it fluctuated. Thankfully, we didn’t consider the issue closed at that point.
Imagine trips to the doctor to have a glass tube inserted in one’s arteries… Thank you, but no thank you, Mr. Hales.
Jean Léonard Marie Poiseuille
Hales’ observation remained interesting but worthless in the field until Jean Léonard Marie Poiseuille, a French physicist, and physiologist invented the haemadynamometer.
Prior to Poiseuille, there was no way to measure the variances in the pressure. He created a mercury manometer, which could measure the rise and fall of blood pressure.
The problem was, Poiseuille’s system, like Hales’, was also invasive. He would insert a thin hollow tube into an artery. At the other end was the mercury manometer.
Humans had been using manometers since the 1600s to measure pressure in other applications, but Poiseuille was the first to apply it to blood pressure.
With each pulse, the pressure of the patient’s blood would move the mercury level. One could measure that displacement to find a benchmark for pressure.
In 1847, a German physician and physiologist, Carl Ludwig added the kymograph to Poiseuille’s design.
Ludwig’s kymograph used a floating pen positioned on a revolving drum to track the movement of the mercury. The result was a wave chart, one that would, in theory, be more accurate than previous measurements.
Again, the instrumentation required punching a hole in the patient’s body, into an artery no less. This was not a marketable idea.
It would be another decade before something better came along.
Etienne-Jules Marey[caption id="attachment_6637" align="aligncenter"] Etienne-Jules Marey | britannica.com[/caption]
In 1855, a French scientist, Etienne-Jules Marey built on a developing concept of a noninvasive system for measuring blood pressure.
The popular theory at the time was that doctors could be able to measure the counter-pressure required to stop a patient’s circulation.
Marey did so by putting the patient’s arm into a sealed glass container filled with water.
He would increase the water pressure until he could detect no circulation in the lower arm. That would be the systolic pressure.
It was crude and wet, but non-invasive.
Samuel Siegfried Karl Ritter von Basch
For three decades, Marey’s water filled tank was the least-invasive way to measure blood pressure, a lab trick, not much more practical for the field that pushing a glass tube into the patient’s artery.
In 1881, Samuel Siegfried Karl Ritter von Basch, an Austrian-Jewish physician living in Mexico, cleaned up this idea.
Most historians credit von Basch as the creator of the first sphygmomanometer. He put a water-tight bag around a manometer bulb, placed it over the wrist of his subject, filling the bag with water until the pulse stopped.
Then, by releasing the pressure he could measure the counter-pressure via the mercury in a manometer connected to his device.
Von Basch’s device only measured systolic pressure, but it was the most user-friendly system yet.
Further Refinements[caption id="attachment_6644" align="aligncenter"] Korotkoff Sounds | slideshare.net[/caption]
A small, but important augmentation to von Basch’s design came from the French cardiologist in 1896, Pierre Potain. He used air instead of water in the compression bag.
Then, a man named Scipione Riva-Rocci changed the bag of air, wrapping it around the arm of the patient, inflated by an attached bulb.
Riva-Rocci would inflate the arm wrap until he could no longer determine a pulse. When he released the pressure, the amount by which the mercury manometer moved was the systolic measurement.
In 1905, Nikolai Korotkoff identified what we call the Korotkoff sounds. He figured out by listening to different sounds in the arteries, he could measure both the systolic and diastolic pressure of the circulatory system.
His method is the one which all medical professionals learn to this day.
Managing blood pressure for most Aussies comes down to lifestyle. It’s our diets, but our stress levels too. A doctor is the best resource for treatment, but common recommendations address diet, exercise, and more recently meditation.
In more serious scenarios, medication can help.
Hopefully, all humanity’s efforts, from theory to application have not been for naught. When was the last time you had your diastolic checked?