Welcome to today's episode, where we'll be diving into the origins and applications of the measurement French, or far as it's commonly referred to. Every day in the endoscopy unit, medical professionals make use of instruments and accessories measured in this unique scale. If you're from Germany or have worked with German tools, you might have heard it referred to as Tch, charr or Chariere. So who exactly was Chariere? Joseph Frederick Benoit Chariere lived between 1803 and 1876. He was a Swiss, french artisan and was pivotal in the design of medical instruments. Though his contributions primarily catered to urology, chariere was versatile. He developed a range of instruments, from scissors and syringes to non-rebreathing systems for administering anesthesia.

What stands out about Chariere's designs is the precision. For medical products to be effective, they must be reproducible and maintain consistent sizes. Addressing this challenge, chariere pioneered a system of gauging now known as the Chariere or French gauge system. This system boasts uniform increments between gauge sizes. In practical terms, one Charr or French is equivalent to 0.333 millimetre. To simplify it further, an increment on the French scale is 1-3 of a millimetre. So a 10-far catheter would be 10 multiplied by 0.33 millimetre, which gives us a calibre of 3.33 millimetre. Here's an interesting tidbit If you're working with a gastroscope that has a 2.8-metre-meter channel, you wouldn't be able to pass any delivery device, stent or pushing catheter that's larger than 8-frahr. This is crucial when deploying self-expanding metal stents, sems, which are typically around 10-frahr. These SEMs are used for specific medical conditions and therefore scopes with larger working channels, like the colonoscope or duodenoscope, are essential. But medicine is all about improvisation. So even without the ideal scope, there are techniques to pass thicker catheters or stents to the desired lesion or position. This might involve tools such as overtubes or guide wires. To give you a clear perspective on the French scale 1-far is 0.33 millimetre, 2-far is 0.66-mere, 3-far is 1-mime-mium, and so on till 20-far, which stands at 6.6.

Now imagine this scenario described in our figure legend. We have the balloon-assisted endoscopic retrograde colongeopancreatography. Initially, a magnetic resonance colongeopancreatography shows a tight distal bile duct stricture. The hepatocogedgenostomy appears to have a tight opening. However, upon balloon dilation of the hepatocogedgenostomy, the balloon-assisted endoscopy over 2B functions as a caesible working channel. With the weirder retained in seed. It connects the balidux to the operator. Using radiological guidance, the operator can advance a fully covered metal stent through the overtube and finally successfully insert the stent inside the bile duct. This procedure, like many others in the medical field, shows the incredible importance of precise measurements and the tools designed by innovative minds like Cherrier. That's it for today's episode. Stay curious and keep exploring.