The catheterization of peripheral veins in small animals is a procedure most veterinary nurses perform on a regular basis, but that is often performed in sub-optimal conditions. The consequences of poor placement and aseptic technique are often not fully appreciated, and this article provides a step-by-step approach for achieving a good placement technique of peripheral catheters. It explains the clinical significance of a good aseptic technique and post placement management to prevent catheter-related complications occurring.
Considerations prior to catheter placement
Location
The species and breed of patient may influence the location of catheter placement. Breed conformity can impair visualization, accessibility and practicality of catheter placement.
Previous or recent catheterization of a vessel may make it unsuitable for repeated use. Patients with conditions such as diarrhoea and polyuria have a higher risk of catheter contamination if catheter placement is performed into a hind limb vessel.
Infection risk
Catheter-related infections are one of the most frequently reported causes of hospital acquired infection seen in humans and animals that are hospitalized (Marsh et al, 2007). A study revealed factors that contribute to the bacterial contamination of peripherally placed intravenous catheters in dogs and cats. Factors examined included whether blood was collected from the catheter immediately after insertion, and infection rate associated with T-connector use, compared with Y-connector use (Jones et al, 2009a). Introduction of bacteria into the catheter hub and migration to the catheter tip, and into the bloodstream has been proposed as the most common route of peripheral catheter-related infection in veterinary patients (Johnson, 2002). This highlights the importance of thoughtful catheter placement and after care to reduce the possibility of infection. Skin microflora has been shown to be the most common contaminant of intravenous catheters in humans (Raad, 1998) therefore it must be concluded that the skin and hair of an animal are also a potential source of contamination. Contamination from the hands of the person placing the catheter has also been reported (Blaiset and Pena, 1995;Raad, 1998; Eggimann et al, 2004).
In the author's experience the donning of gloves for preparation and placement of short-term peripheral catheters is not widely instigated. If gloves are not used, hand hygiene procedures should always be instigated prior to peripheral intravenous catheter placement.
Aseptic preparation
Hair removal and effective aseptic preparation should be performed prior to catheter placement. A study has shown that correctly applied antiseptics are still effective in the presence of hair (Geraghty et al, 2009), but good practice would dictate that the hair should be clipped from the proposed venepuncture site using a clean, intact clipper blade. This will aid in the visualization of the vein and ability to anchor the catheter securely. Shaving of the hair using a surgical blade is not recommended because of the creation of microabrasions, which have been associated with wound infections (Mishriki et al, 1990). Figure 1 shows the preparation of the lateral saphenous vein for catheter placement.
The skin of normal dogs has been reported to have resident and transient bacteria present, including Staphylococcus spp., Streptococcus spp. and Pseudomonas Spp. (Muller et al, 1989). As most catheter-related infections are caused by bacteria introduced from the skin at the time of catheter insertion (Tann et al, 2003) and catheter-related complications have been found to be higher when no skin preparation was used in humans (Smallman et al, 1980), a method of skin preparation should be employed. Comparisons have been made between several antimicrobial preparation solutions, including chlorhexidine gluconate and povidine-iodine compared in combination and against untreated skin. It has been shown that preparation of the venipuncture site with chlorhexidine gluconate was superior to povidine-iodine in reducing bacterial colonies on skin (Osuna et al, 1990) and even a single wipe of chlorhexidine dramatically reduced bacterial colonization (Dorey-Phillips et al, 2008). Coolman et al (1998) stated that ‘the importance of aseptic skin preparation increases with the duration of catheter dwell time’. However, aseptic skin preparation at the catheter insertion site should be performed for all catheter placement, regardless of the anticipated length of catheter dwell time to reduce potential contamination. Figure 3 demonstrates poor placement technique
Catheter connector systems
The introduction of bacteria into the catheter hub is thought to be a common route of peripheral catheter infection, with the migration of the bacteria to the catheter tip and into the bloodstream (Johnson, 2002). Studies have been performed to investigate whether certain styles of connector increase the incidence of catheter-related infections. Results have been varied and indicate that the length of the connection system may influence the retention of bacteria and further studies are required on this area. Although these studies are inconclusive, logic would imply that increased frequency of disconnection may increase the possibility of catheter hub contamination. Secure stabilization of the catheter and connector is required to reduce catheter movement at the insertion site and movement of the catheter within the vessel that could lead to phlebitis of the vessel.
Post placement maintenance
Dressings can be used to prevent gross contamination of the catheter site and aid in stabilization of the catheter and connection system. The efficacy of sterile dressings and topical antiseptics/antibiotics may be controversial (Tan et al, 2003). Catheter flush solutions are intended to prevent thrombus formation, not prevent infection and use of anticoagulants (heparin solution) with sterile sodium chloride is controversial, but twice-daily flushing using either solution is recommended for catheter patency (Tan et al, 2003). Catheter flushing may not be required if intravenous fluid solutions are continuously administered. The catheter insertion site and vessel should be inspected for signs of infection and phlebitis at least once daily, preferably more often, and could be combined with flushing of the catheter. Human nursing guidelines for peripheral catheter management (Scales, 2008) could be adapted for use within the veterinary field.
Conclusion
If performed using a good placement and aseptic technique, catheter-related infections and complications can be reduced. Thoughtful placement and correct aftercare will influence the dwell time of the catheter. Further studies regarding infection control connected with intravenous catheter placement in animals may provide useful evidence that could influence future placement protocols.