Central venous catheterisation - 5
Maintenance of the insertion site
A number of methods have been used to try and reduce complication rates at the insertion site.
Ointments, subcutaneous cuffs and dressings
Application of antibiotic ointments (eg bacitracin, neomycin and polymixin) to catheter insertion sites increases the rate of catheter colonisation by fungi, promotes the emergence of antibiotic resistant bacteria and has not been shown to lower the rate of catheter related infections. These ointments should not be used.
The use of silver impregnated subuctaneous cuffs were also in vogue for a time as a tool to prevent infection, however, they have also not been shown to reduce the incidence of infections and are also not recommended.
Numerous studies have been done regarding frequency of dressing changes and type of dressing used (gauze vs transparent material) with no clear conclusions. It may be that the increased handling with frequent dressing changes is a major factor in the rate of infection. Therefore, adhere to local guidelines.
Hubs and needleless access devices
The hubs of the catheters are commonly a source of contamination, particularly if they have been in a long time. There are antispetic containing hubs on the market which have been shown to be effective in reducing infection rates.
Needleless access devices have been linked to an increase in infections. This has been attributed to high rates of non compliance with manufacturer's instructions to change the end cap with each use and change the device every 3 days.
Remove the CVC as soon as you can
Removal of the catheter (or any) should occur as soon as it is no longer needed, since the probability of catheter related infections increases over time - particularly after 5-7 days.
Numerous studies of scheduled routine replacements have failed to come up with a strategy to decrease the rate of catheter related infections, and against this must be factored the risk of a mechanical complication occuring with insertion at a new site.
What to do if you suspect a catheter related bloodstream infection
Signs and symptoms of infection without another confirmed source should raise the concern that the catheter is the cause of the symptoms.
Once this is suspected, take blood samples from the catheter for culture to look for bacteraemia. Cultures of blood from peripheral sites should also be taken. This is because if the culture of the blood from the catheter is positive, it is difficult to ascertain where the source of infection is - hub, catheter colonisation or within the blood stream from the catheter.
However, if a negative catheter culture is obtained, it is unlikely that the CVC is the cause of the infection.
Types of cather associated infections
Catheter colonisation - growth of organisms from a catheter segment when cultured
Catheter related blood stream infection - Isolation of the same organism from blood culture and a catheter segment, with clinical symptoms of infection without any other source
Exit site infection - Tenderness, redness, induration or pus within 2 cm of the exit site of the catheter
If there is any pus or redness at the exit site infection is likely and the catheter should be removed.
If the patient has septic symptoms empirical antibiotic therapy should be begun to treat Staphylococcus infections. Antibiotics covering gram negative organisms should be added, particularly for immunocompromised or neutropenic patients.
If the patient is in septic shock, with no other source of infection, the catheter should be removed and a replacement inserted at a new site.
Culture the catheter tip
When removing a central line from a patient who appears to have an infection, always send the tip for culture, as this may confirm the organism responsible.