Blood pressure is a fundamental health measurement, representing the force exerted by circulating blood against artery walls. This reading offers medical professionals a quick snapshot of cardiovascular state, indicating conditions like hypertension, a major risk factor for heart disease and stroke. The device used to take this measurement, the blood pressure cuff or sphygmomanometer, is the result of centuries of scientific inquiry. This history traces the evolution from dangerous animal experiments to the standardized clinical tool used today.
Early Attempts at Measuring Pressure
The earliest attempts to quantify blood pressure were highly invasive and performed on animals. In 1733, Stephen Hales inserted a brass tube and a nine-foot glass pipe into a horse’s artery. He observed the blood rise over eight feet, providing the first quantitative measure of arterial pressure. This direct method was entirely impractical for human use.
Later, in the 19th century, the non-invasive sphygmograph emerged. German physiologist Karl von Vierordt developed the first external device in 1854, using weights to apply pressure until the pulse disappeared. Étienne-Jules Marey improved this device in 1863, making it portable and able to record a pulse wave graphically. However, the sphygmograph did not provide a definitive numerical measurement of absolute blood pressure, limiting its clinical utility.
The Invention of the Sphygmomanometer
The sphygmomanometer was first introduced by Austrian physician Samuel Siegfried Karl Ritter von Basch in 1881. Von Basch developed a device using a water-filled rubber bulb placed over an artery, connected to a manometer to measure pressure. The examiner pressed the bulb until the pulse was obliterated, and that reading was considered the systolic pressure. This provided the first quantifiable, non-invasive pressure reading.
A substantial improvement came from Italian physician Scipione Riva-Rocci in 1896. He introduced a wide cuff that encircled the upper arm, distributing compression pressure more evenly. Riva-Rocci’s mercury sphygmomanometer was easier to use and more accurate than von Basch’s design. His method still relied on palpation, determining systolic pressure by releasing the cuff until the radial pulse was felt again at the wrist.
Standardizing Clinical Measurement
The non-invasive measurement technique was perfected in 1905 when Russian physician Nikolai Korotkoff presented a new method transforming the procedure from palpation to auscultation, or listening. Korotkoff realized that by placing a stethoscope over the brachial artery below the cuff, he could hear distinct sounds as the pressure was released. These sounds, known as Korotkoff sounds, allowed for the measurement of both systolic and diastolic pressures.
Korotkoff described five phases: the first audible sound (Phase I) marks the systolic pressure, and the point where the sound completely disappears (Phase V) corresponds to the diastolic pressure. This auscultatory technique provided a far more accurate and comprehensive reading than the previous palpation method. The combination of Riva-Rocci’s robust arm cuff and Korotkoff’s auditory technique created the standardized procedure that is still the foundation of modern blood pressure measurement today.