List the mechanisms of central venous catheter infection, and llst the measures you undertake to prevent this infection.
Usual source of infection is the insertion site, hub, infusate or haematogenous spread from distant site. Major mechanisms causing CVC infection are therefore:
(1) Contamination during insertion. Prevented by:
• Sterile precautions during insertion (gloves,.gown, mask, appropriate cutaneous antiseptic)
(2) Contamination of insertion site after insertion:
• Use of subclavian site for insertion (rather than jugular or femoral)
• Adequately fix catheter to prevent movement
• Use appropriate combination of dressings and observation of site (change dressing if soiled)
• Avoid prolonged connection of solutions prone to contamination (lipid, propofol)
• Remove catheter as soon as need for it diminishes
(3) Subsequent contamination due to breaking of sterile connections (multi-flows, 3-way taps):
• Limit number of lumens, decrease breaks in system, clean injection ports before accessing system (eg. Alcohol), use alternate route for blood transfusion
• Use of anti-microbial impregnated catheters
(4) Subsequent contamination from systemic infection elsewhere:
• Aggressive treatment of other infections, remove catheters as soon as possible
• Use of anti-microbial impregnated catheters
The second part of this question is similar to Question 8 from the first paper of 2006, which asks the candidate to "Outline strategies you would incorporate to prevent central venous catheter related infection.". I reproduce the answer below, for convenience. A good article from 2002 reviews the risk factors for CVC infection, which resembles the college answer.
Mechanisms of CVC infections
Prevention of CVC infections
This is a point-form synopsis of CVC features and practices associated with a decreased risk of CVC infection:
Marschall, Jonas, et al. "Strategies to prevent central line–associated bloodstream infections in acute care hospitals: 2014 update." Strategies 35.7 (2014): 753-771.
ANZICS statement on prevention of central line associated infections
ANZICS statement on insertion and maintenance of CVCs
.LIFL have made as short a summary as one can manage without omitting vital facets of the overall strategy.
Safdar, Nasia, and Dennis G. Maki. "The pathogenesis of catheter-related bloodstream infection with noncuffed short-term central venous catheters."Intensive care medicine 30.1 (2004): 62-67.
Safdar, Nasia, Daniel M. Kluger, and Dennis G. Maki. "A review of risk factors for catheter-related bloodstream infection caused by percutaneously inserted, noncuffed central venous catheters: implications for preventive strategies."Medicine 81.6 (2002): 466-479.