Saturday October 07, 2006
French And Gauge


For Diameters of needles, catheters, tubes and wires there are 2 essential systems and it is important to understand the difference between two.

Gauge

Intensivists perform multiple procedures and use different wires while utilizing Seldinger’s technique or needles and IV catheters.

A traditional unit measuring the diameter (or the cross-sectional area) is Gauge. Various wire gauge scales have been used in the U.S. and Britain. The Stubs Iron Wire Gauge system (also known as the Birmingham Wire Gauge) is used in medicine to measure the diameter of hypodermic needles, intravenous catheters, and suture wires. It was originally developed in early 19th-century in England for use in wire manufacture, and it began appearing in a medical setting in the early 20th century. the Gauge system is not truly linear.

Needles / IV catheters: The needle gauge is inversely proportional to its diameter, so the larger the gauge number, narrower the diameter. Click here to see Needle Gauge Chart.

Wires: In traditional scales (U.S. STANDARD WIRE GAUGE), larger gauge numbers represent thinner wires. (For very thick wires, repeated zeros are used instead of negative numbers, so gauges 00, 000, and 0000 represent -1, -2, and -3, respectively.) For example, 0000 gauge represents a wire having a diameter of 0.46 inch and 36 gauge represents a diameter of 0.005 inch. Click here to see the table for U.S. STANDARD WIRE GAUGE.

French Sizing

Joseph-Frederic-Benoit Charriere was a 19th century maker of surgical instruments. Charriere made significant advances in ether administration, urologic, and other surgical instruments. He has credit of inventing the modern syringe. But his most significant contribution is to develop a uniform , standard gauge specifically designed for use in medical equipment such as catheters, drains and probes. Remember ! British system is not linear and confusing as Gauge # gets bigger, the diameter get smaller. Unlike the British gauge system Charriere's system (or French Gauge) has uniform increments between gauge sizes ( 1 French = 1/3 of a millimeter) and is easily calculated, linear and predictable like:

1 French = 1/3 of a millimeter , so
5 French = 1/3 x 5 = 1.66 millimeter


French Gauge sytem is mostly use for drains and tubes.