- Peripheral intravenous cannulae aka “venflons”
- IV fluid administration
- blood sampling
- drug administration
- needle thoracostomy for tension pneumothorax
- needle cricothyroidotomy
- different devices and brands available with different lengths and diameters.
- commonly 14–24 Gauge.
- plastic cannula (PTFE or similar material) mounted on a smaller-diameter metal needle, the bevel of which protrudes from the cannula.
- flashback chamber that fills with blood when the vein is successfully cannulated.
- standard Luer-lock fitting for attaching a giving set so fluids/drugs can be administered.
- safety features that allow the needle to be retracted inside the cannula and be disposed of in one piece.
METHOD OF INSERTION/ USE
- superficial veins of the upper limbs are preferred.
- veins are filled by use of a tourniquet and the vein immobilised by finger traction on the adjacent skin.
- cannula is held at ~20° to the skin and the vein punctured
- needle is inserted far enough that the tip of the cannula also enters the vein (i.e. advance 1-2 mm following flashback)
- cannula is advanced and the needle pulled back.
- needle is disposed of in a sharp container once the cannula is advanced to the hub
- PIVC is secured with adhesive dressing
- Failed cannulation
- Haematomas/damage to underlying structures
- Extravasation of fluids/drugs
- Insertion site infection
- Inadvertent arterial puncture
- operator needlestick injury
- Flow is determined by size and diameter of the cannula (see gas cylinders and Hagen-Poiseuille Equation). For resuscitation short, wide-bore cannulae provide the most rapid infusion rate.
- Gauge is used to describe needles – larger Gauge corresponds to smaller needle diameter
- French catheter scale (ka French Gauge) describes catheters – larger French size corresponds to larger catheter diameters (1Fr = 0.33 mm)
- Cannula is a term used for catheters 7 cm or less in length
Replacement of peripheral cannulae
- Many centers have a policy of routine replacement of peripheral IV cannula at 72-96h (with the intention of decreasing complications such as infection)
- Replacement causes additional discomfort to patients and is non-trivial in patients with difficult IV access
- According to the Cochrane review of the topic, there is no evidence to support changing catheters every 72 to 96 hours
- The insertion site should be inspected at each shift change and the cannula removed if there are signs of inflammation, infiltration, or cannula blockage
References and Links
- Webster J, Osborne S, Rickard CM, New K. Clinically-indicated replacement versus routine replacement of peripheral venous catheters. The Cochrane database of systematic reviews. 4:CD007798. 2013. [pubmed]