Guidewire, Catheter,Puncture Needle Models in One Article

Specification of puncture needles

puncture is the technical basis of interventional radiology, puncture needle is the hands of interventionalists, but the clinical unit of puncture needle is not uniform, which is easy to cause bias in understanding. Europe and the United States the unit of puncture needles for “G”, China’s use of mm there is a big difference. For example: China’s puncture needles, the larger the number of provisions of the puncture needle is also the thicker, and Europe and the United States puncture needle products “G” the larger the more fine.

Domestic puncture needles are expressed by the number of the outer diameter (GB system), the outer diameter of 0.7mm is called No. 7, the outer diameter of 1.2mm is called No. 12; international puncture needles are expressed by G (G).

Internationally G (Gauge) that the outer diameter, 16G outer diameter of 1.6mm, coarse needle every increase in a unit, the outer diameter decreases by 0.2mm, such as 17G outer diameter of 1.4mm; every decrease in a unit, the outer diameter increases by 0.2mm, such as the 14G outer diameter of 2mm. coarse needles, there is also an empirical formula for calculating the outer diameter, that is, the outer diameter = (24 – number) / 5, such as 16G For example, for 16G needles, OD = (24-16)/5 = 1.6mm; for 18G needles, OD = (24-18)/5 = 1.2mm; this empirical formula is not suitable for fine needles, the formula for fine needles is OD = (36-digit)/20, e.g., OD of 20G needles = (36-20)/20 = 0.9mm, OD of 22G needles = (36-22)/20 = 0.7mm. 20=0.7mm.

The tube wall thickness is about 0.1mm and the difference between the OD and ID is close to 0.2mm.

There is also a length unit need to be familiar with, that is, inches, 1 inch = 25.4 mm; for example, the specification of the piercing needle is 22G1″, which means that the thickness of the needle is 22G, that is, the outer diameter is 0.7mm, the length of the needle is 1 inch, that is, 25.4mm.

Guide Wire Specifications

The guidewire provides guidance and support for catheter insertion into the blood vessel and assists in the placement of the catheter during elective and super-elective intubation. The guidewire has a relatively soft tip of 3 to 5 cm to prevent damage to the vessel lining. The shape of the soft anterior segment can be categorized as straight or curved. The most commonly used thickness is 0.035in (1in = 25.4mm), and 0.018 to 0.02 guidewires are finer and are used for renal artery and below-the-knee angioplasty.

Guidewire diameters are measured in inches. “035” means that the diameter of the guidewire is 0.035 inches. The available guidewire diameters are “010, 014, 018, 025, 035 and 038”. Each wire diameter has a matching catheter. The most commonly used guidewire sizes are “014 and 035”. For example, 0.035in (0.035×25.4mm=0.89mm).

There are two kinds of domestic specifications of guide wire, one is more than 130cm long, thicker, suitable for more than 6F catheter, and the other is less than 130cm long short wire, thinner, suitable for less than 5F catheter, both are straight fixed core, the front section has a soft section of about 5cm. There are many foreign specifications, ranging from 40 to 300CM long, and the thickness of the guidewire is usually expressed in inches or mm. Expressions are.

1.SF/25/145 for the safety guide wire / outside diameter of 0.025 inches / 145CM length

SF/35/145 for safety guide wire / OD 0.035 inches 145CM long

Or SF-21-80-BH for straight standard guidewire – 0.021 inch (0.53mm) OD – 80cm long – with heparinized Teflon sheath.

2.T DW-45-65-10-BH indicates a rotating guidewire – OD 0.045 inches (1.14mm), length 65CM – anterior bending radius 10mm – heparinized Teflon sheath.

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Catheter Size

Clinics often encounter many different units to express catheter size, commonly used units include Inch, French (abbreviated as F or Fr). Knowing how to convert different units will enable you to quickly choose the right catheter and optimize treatment. Due to the thickness of the wall, catheter diameters are divided into outer and inner diameters: OD (outer diameter) indicates the outer diameter of the catheter; ID (inner diameter) indicates the inner diameter of the catheter. ID and OD are usually measured in inches (In) or millimeters (mm).

The following will introduce a few units commonly used in the calculation of conduit size:

1, Inch – inches (inch): unit of length, commonly used in the United Kingdom, Canada, the United States

-1 inch = 100 cents = 1,000 British millimeters ≈ 0.02778 yards = 2.54 centimeters – 1 cm ≈ 0.3937 inches

-1 millimeter ≈ 0.03937 inches.

2、French (F/Fr)
Fr is the unit of catheter, originally is the unit of measurement of circumference, is a French doctor invented, for the English abbreviation of French. 3F = 3mm circumference, and because the circumference = 3.14 × diameter, so the diameter of 1F ≈ 0.33mm. 1F increase in the outer circumference of the catheter is equivalent to the outer diameter increase of 0.33mm. 3F catheter diameter of about 1mm. 1F is the minimum value of the French, maximum There is no upper limit.

Note: In general, the sheath size is the inside diameter (ID) and the catheter size is the outside diameter (OD), so a 5F catheter can be placed in a 5F catheter sheath (the sheath OD is 7F, depending on the material). If the catheter used is of the same type as the sheath (e.g., a 5F catheter in a 5F sheath), the catheter will completely obstruct the lumen of the sheath, and it will not be possible to inject contrast and heparin saline through the lateral arm of the sheath.

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