The Pachon Oscillometer, the beginning of the future

It is in 1910 that Victor Pachon, professor of medicine at the University of Bordeaux, invents a device that was to have a seminal influence on the future of blood pressure, the oscillometer, which today still carries his name. This device was used in daily medical practice by thousands of doctors, well into the 60ies.

Although originally rejected by Pachon's contemporaries because of the inherent difficulties in its usage, it was soon accepted as a standard device for medical doctors, especially in the countryside and was greatly used during the first world war.

It was the first device that allowed a more or less accurate diagnosis of systolic and diastolic pressures without the use of a stethoscope.

It consisted of a hermetically closed metallic casing connected to a Gallavardin cuff and a hand-operated bicycle pump. It had two screens, the largest of which displayed with a long needle the amplified variations of pressure within a manometric capsule connected to the cuff, whereas the smallest screen displayed the internal pressure inside the device.

The future is often nebulous, but it is not a reason for us not to invent it...

The doctor inflated the Gallaverdin cuff and observed the pressure oscillations on the big screen. When the display indicated 20 (200mmHg), he deflated the cuff slowly using a decompression screw and noted the pressure when the basal oscillations suddenly increased in amplitude. This was the systolic pressure. The oscillations then reached a maximum (the "oscillometric Index"), then started decreasing in amplitude. This measurement of pressure was not particularly accurate as it was based on the doctor's subjective appreciation of the amplitude of the oscillations. But it did herald the beginning of a great new science, the measurement of blood pressure.