Measurements Gauge The sizes of needle-based instruments (such as Venflons and needles themselves) are measured in 'Gauge' (ie. how many can be fitted into a tube of a fixed diameter). In Gauge, larger numbers, mean smaller diameter lumens.
French Catheters use the 'French' system. This is the circumference of the tube in millimetres, eg. a 30F catheter has a circumference of 30mm. In French, larger numbers therefore mean larger diameter lumens. Bear in mind that catheters with greater French are often more 'stiff'. Paradoxically, it can therefore sometimes be easier to try a greater sized catheter if insertion is proving difficult (eg. in elderly men with enlarged prostates). Remember, however, never to force the catheter - it should pass smoothly.
Needles Sizes & colour-coding Needles are colour-coded depending upon their diameter:
- Green (21 gauge, 0.8mm)
- Blue (23 gauge, 0.6mm)
- Orange (25 gauge, 0.5mm)
Local anaesthetics: Wide-bore needles (green) should be used to draw up the LA, and narrow-bore (blue or smaller) should be used to administer the drug itself (depends upon the site and nature of the administration).
Cannulae (Venflons) Sizes & colour-coding Cannulae are also measured in gauge, and are also colour coded:
- Blue 22G (very small - for difficult hand veins)
- Pink 20G (small - suitable for the majority of patients that require IV fluids)
- Green 18G (average sized - suitable for IV fluids and smaller blood transfusions)
- Grey 16G (large - for use in large blood transfusions and emergency use)
- Brown 14G (very large and painful - again, for emergency use)
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Last Updated ( Tuesday, 23 September 2008 21:28 )
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