Vetlexicon Bovis from Vetlexicon | Definitive Veterinary Intelligence

Introduction

Thrombophlebitis (TP) is inflammation of a vein associated with a clot of blood.
It is the most commonly reported complication of venous cannulation in veterinary medicine.
Septic thrombophlebitis (STP) is where the inflammation is accompanied by a bacterial infection.
The jugular vein is the most commonly cannulated vein in cattle, although cephalic veins can also be effectively utilised. TP/STP of the jugular vein may have serious consequences.
This condition is rarely seen in cattle as cannulas are usually only placed for short-term use and can be difficult to maintain.

Cattle are particularly dextrous at removing jugular venous cannulas with hind-feet and so, if left unattended, jugular venous cannulas should always be wrapped to prevent cannula loss and damage to the vein.
Risk factors

Patient related factors:
- Malnutrition/debilitation.
- Impaired immune status, eg neonates or sepsis.
- Concurrent infections/bacteraemia/SIRS.
- Skin infection.
- Coagulopathies.
Cannula related factors:
- Certain materials are less thrombogenic than others, eg polypropylene> polytetrafluoroethylene (PTFE/ Teflon) > silastic > PVC > polyurethane BUT in vivo the softness of the material, which may increase at body temperature, also plays a role. In some studies, silastic cannulas were less thrombogenic c.f. polyurethane. Some materials, eg polyurethane are available impregnated with bacteriostatic/bacteriocidal agents to further reduce bacterial colonisation and risk of STP. Some materials may not be appropriate for use in cattle due to cost or lumen diameter too small.
- The more material a cannula has that can be in contact with the vessel lining means more thrombogenicity: thus larger bore, longer cannulas will cause more reaction than narrower, shorter ones. The reason most long stay cannulas are long is partly due to the fact that a longer cannula is less likely to be pulled out of a vein but also because most of these cannulas are designed for use in humans and so a 30 cm cannula in a person will lie in mid-flow of the blood in a central vein and thus will not cause much irritation to the tunica intima of the vessel.
- Duration of dwelling in vein.

Check with manufacturer the duration for which the various different cannula types are designed to remain in a vein, eg Teflon cannulas should not be left in situ for more than 24-48 h.

Cannula placement/care:
- Lack of aseptic technique.
- Technique of placement: over-the-wire (Seldinger) or through-the-cannula (peel-away) cannulas are less likely to be associated with problems than over-the-needle cannulas.
- Damage to cannula when placed, eg an incision through the skin is essential in cattle due to thickness of skin. Trying to insert a cannula without a skin incision results in damage in the distal portion of the cannula. It also means that a piece of skin passes into the jugular vein, which will contain skin commensals that can colonise.
- Mechanical trauma to vessel and surrounding tissues: poor placement, cannula not secured properly, cannula kinked etc.
- Cannula causing turbulent flow of blood will increase thrombus formation, ie a cannula placed against the flow of blood/up the vein.
- Cannulas should be sutured securely to the skin in order to minimize movement of the cannula thus minimising damage to the intima of the vein.
- Cannula not flushed regularly: indwelling cannulas should be flushed regularly.
- Lack of care in maintenance of clean/aseptic handling of cannula, eg bottle tops and bungs not swabbed with spirit etc.

Competence in performing these techniques is important.

Drug administration:
- Total Parental Nutrition (for TPN a double lumen cannula should be used to avoid irritation of the vein) or 40-50% dextrose/glucose as these solutions are hypertonic/hyperosmotic.
- Certain drugs are irritant when administered intravenously, eg hypertonic fluids, particularly hypertonic saline, thiopental, Metamizole Metamizole (dipyrone), (guaifenesin – not licensed in cattle in most regions).
- Home-made intravenous solutions may be more likely to cause thrombophlebitis. Fluid therapy