The placement of an intravenous catheter is a task that many nurses perform on a daily basis. Correct placement and care of these catheters is vital whether used for a single intravenous injection or to provide long-term vascular access in a hospitalised patient. Intravenous catheterisation may be indicated for a variety of reasons and certain factors will influence the location and type of catheter that is placed. Before embarking on catheter placement the reason for requiring vascular access should be considered.

Factors that may influence the location of catheter placement may include:

 Patient size and species

 Accessibility of veins/has vascular access been attempted previously?

 Are there any lesions or wounds that should be avoided?

 Amount of restraint required--wiggly puppy, aggressive patient, ophthalmic patients with fragile eyes (e.g., deep corneal ulcers)

 Does the patient require a radiographic study/ surgery on a particular limb

Factors that may influence the type of catheter placed may include:

 What the catheter is to be used for--drug administration, obtaining blood samples, chemotherapy, total parentral nutrition

 The length of time that the intravenous access may be required for--induction of anaesthesia, long-term fluid therapy

There is a large variety of catheters available including over-the-needle, through-the-needle, winged and multi-lumen central catheters. The manufacturing material of the catheter can influence its characteristics, such as rigidity, smoothness of the external surface and potential for causing thrombosis and phlebitis of the vessel. Materials including teflon, polypropylene, polyurethane and silicone are commonly used. Catheters coated or impregnated with radio-opaque metal salts, such as barium, allow radiographic identification in the case of catheter fragmentation. Elastomeric hydrogel is a material that allows hydration of the catheter by plasma water after insertion; this enables the catheter to become softer and less traumatic to the vessel.

Choice of catheter may be decided by personal preference, familiarity with use and patient requirement. The length and diameter of the catheter selected must be appropriate for its intended use and location of insertion. Smaller diameter catheters made of a softer material may be less traumatic to vessels, but will limit the flow that can be administered. Larger rigid catheters that may be easier to advance through the skin may be more prone to kinking, causing damage to vessel walls. Most commonly vascular access is achieved by catheterisation of peripheral veins such as the cephalic and accessory cephalic of the thoracic limb and the lateral saphenous of the pelvic limb. The medial saphenous may also be used but ensuring the catheter is adequately secured can be troublesome. The femoral vein may be used in cats and auricular veins may be used in dogs with large ears such as Basset Hounds. External jugular and medial saphenous veins are used for the placement of centrally situated catheters.

All catheter placements should be performed using a strict aseptic technique to minimise bacteraemia and septic complications. The gaining of vascular access in an emergency situation, such as cardiopulmonary cerebral resuscitation, is the only situation where preparation may be limited or omitted. An example of an aseptic preparation would be:

1.  The hands of the person placing the catheter should be washed prior to placement.

2.  An area over the vein is closely clipped and loose hair removed; the area is cleansed with chlorhexidine gluconate applied to a cotton wool or gauze swab and surgical spirit applied and ideally left to dry.

3.  The catheter is introduced ensuring that the catheter length is not touched during insertion.

4.  Once placement is satisfactory the catheter hub is closed with a sterile port and the catheter is secured in place and a protective bandage applied if required.

When securing the catheter in place, using either adhesive tape or sutures, it is important that the catheter does not move within the vein. Any movement may cause damage to the vessel, which may increase the risk of thrombus formation and phlebitis. Movement from the dragging of fluid lines must also be reduced. A small portion of the tubing line could be included within the bandage to allow any pulling movement to be exerted on to the tubing line rather than directly upon the catheter. Movement may also allow the entry of surface skin bacteria around the catheter insertion. Patient limb position can lead to occlusion of the catheter if placement is close to a joint, i.e., elbow flexion. Placement of a rigid short-stay catheter over a moving joint, such as a lateral saphenous catheter may cause vessel trauma due to movement, and inadequate securing of the catheter due to location.

Centrally situated catheters allow cannulation of larger vessels. The deep internal placement of these catheters means that movement and patient position does not occlude flow. These long catheters are made from silicone, is more inert than other material and requires specialist insertion techniques often using guide wires, performed in a surgical aseptic manner. With correct placement and care these catheters can stay in place for longer periods of time. Central catheters are often multi-luminal which allows infusion of incompatible solutions through a single catheter; they are safer for administering irritant solutions, such as hypertonic saline, as the solution is delivered deeply into the vessel, avoiding possible extravasation of the drug. Central catheters can be secured adequately with sutures and can also be used for central venous pressure measurements, total parenteral nutrition and the withdrawal of blood samples. Placement is normally performed via the external jugular veins but certain conditions, such as raised intracranial pressure and fragile ocular ulcers, may warrant the avoidance of occlusion of the jugular vein, and hence possible increase of intracranial pressure during insertion. In these situations a peripherally inserted central catheter may be placed via the medial saphenous vein.

The aftercare of intravenous catheters is important to avoid complications and ensure that the catheter can stay in place for the desired length of time. Catheters should be flushed with around 2 ml of sterile saline at least every 12 hours. Heparinised saline flush can also be used, but care should be taken with its dilution and use when being used frequently especially in small patients or those with coagulopathies. Central catheters require flushing every 8 hours with about 5 ml of flush down each port.

Any bandage covering catheters should be removed fully to allow inspection of the catheter site at least twice daily; the surrounding skin should be examined for signs of redness, local inflammation or discharge. Adhesive tapes must be examined for tightness and dryness; bandage contamination from vomiting, urine, diarrhoea and spilt water bowls must be replaced. Hindlimb catheters should be avoided in patients with diarrhoea or polyuria. Care should be taken to ensure that the ends of giving sets and ports are not contaminated during disconnection; bungs and tubing ends should be stored correctly in sterile pots; and clean areas should never allowed to drag along the floor. Ports should be swabbed with alcohol prior to injection.

Infection could be introduced from skin contamination at insertion, contamination from patient interference, soiled bandages or inadequate care. Any patient with an indwelling catheter that becomes unexpectedly pyrexic, systemically unwell or shows signs of localised pain or inflammation must be investigated for a catheter-related infection. Suspicious catheters must be removed in an aseptic manner and submitted for bacterial culture. Short, rigid over-the-needle catheters can stay in situ for up to 72 hours and central catheters can stay in place for up to 7 days if properly cared for. Any cut-down incision that is made prior to placement can increase the potential of infection and these catheters should be replaced or removed as soon as possible. Catheters should be removed when no longer needed i.e., when a full recovery from anaesthesia is achieved or intravenous drugs are no longer required.

Air embolisms can occur if ends become inadvertently disconnected or air is present within an administration set; central catheters have the highest risk of incidence as air can be sucked in due to pressure within the thorax. Exsanguination can also occur if disconnection goes undetected, but is more commonly due to patient interference; Elizabethan collars should be used when required.

Catheter embolisms can occur if a fragment of the catheter becomes free within the vessel; radio-opaque catheters allow radiographic investigation to locate any such fragments.

Thrombus formation can occur when there is epithelial damage within a vessel. This could be at the time of insertion or at a later point between the vessel and the catheter itself. Smaller veins with lower blood flow, the use of rigid or less inert catheters, insertion over a moving joint, pre-existing conditions such as autoimmune haemolytic anaemia or vasculitis may all increase the risk of thrombus formation. Severe thrombus formation could lead to pulmonary thromboembolism. Inflammation of the vessel wall (phlebitis) can cause damage to the endothelial lining of the vessel and result in a hardening of the vessel even after the catheter is removed. Extravasation of drugs should be avoided by careful placement of catheters, and irritant drugs should be diluted or administered into veins with a high blood flow to reduce irritation.