Question 14

College answer

Syllabus topic/section:

2.1.19 Intensive Care Procedures: Central venous catheter
2.1.3 Sepsis and Infections: Sepsis and septic shock: L1

Discussion: 

This is a difficult clinical scenario which is sadly not unknown in complex long term critically ill patients. For part a) many candidates provided a definition for calculating CLABSI incidence for quality assurance rather than providing the clinical definition asked for.

In part b) candidates were able to provide the technical reasons why salvage may be preferred (coagulopathy, lack of access sites, quality of life issues overriding catheter re-insertion) but many could have extended their answers beyond technical difficulty when considering a decision about salvaging an infected line.

A few candidates outlined the role of the infecting micro-organism in such decision making and this depth of detail is to be commended. For example, a Coagulant negative staph or drug susceptible Enterobacteriaceae would be a consideration on embarking on salvage therapy whereas a presence of a fungal infection, MROS or Pseudomonas would be more likely to advocate for removal.

In managing a clinically infected line when salvage is being attempted, there was a lot of emphasis on infection control measures but insufficient specific detail about additional management or monitoring for potential complications/treatment failure with a salvage strategy (disseminated infection, thrombophlebitis, persistently positive BC). Details of specifics of Antibiotic lock therapy, systemic Antibiotic therapy (and timing) and guide wire exchange as a last resort were features of the above standard answer.

Discussion

a) The definition of CLABSI is "a laboratory-confirmed bloodstream infection in a patient where the central line was in place for over 48 hours on the date of the event, where the organism cultured from blood is not related to an infection at another site"

The CLABSI incidence rate calculation, which was not asked but which apparently formed a part of some the trainee answers, was CLABSI rate = (Number of CLABSI / number of central line days ) ×1000, i.e. CLABSI rate is number of CLABSIs per 1000 central line days. 

b) Potential circumstances where salvage of the infected central line catheter may be
preferable to removal:

• Catheter is difficult to resite
  • The patient has thrombosis or stenosis of common sites
  • expertise to resite the catheter is not readily available
  • IR guided approaches are not available
  • the catheter 
• Catheter is dangerous to resite or remove
  • the patient is profoundly cogulopathic
  • The patient has extremely fragile skin, burns, or some kind of desquamative skin condition, making resiting adhesive dressings more difficult
  • The catheter is long-term and has adhesions that will require surgical removal, and the patient is for whatever reason opposed to surgery or has contraindications to it
• Catheter is easy to decontaminate
  • The organism is susceptible to first tier therapies
  • The organism is a low virulence organism
  • The patient is at low risk from sepsis (eg. fully immunocompetent and otherwise fit and healthy)
• Catheter is essential for lifesaving therapy
  • eg. the patient depends on it for dialysis 

Though it was not specifically asked about, one might consider answering with a list of scenarios where the catheter, no matter how precious, should be removed anyway. Here's the 2009 IDSA take on the indications for mandatory removal of an infected CVC:

• The patient is in florid septic shock because of the infected line
• The organism is a high-virulence organism (eg. S.aureus, Enterococcus, Candida, mycobacteria)
• The site is grossly contaminated, i.e. it looks so gross that it would be embarrassing to keep the line in
• The patient already has endocarditis
• You tried to manage things conservatively, but the bacteremia continues despite 72 h of correct antibiotics

Specific management of the catheter if salvage is attempted:

• Rewire the line (guidewire exchange)
  • most likely to work where there is only one lumen convincingly contaminated in a multilumen line
  • Does not prevent the need for concomitant antibiotics
• Treat systemically with a prolonged course of antibiotics. 
  • 4-6 weeks, as if they already have infective endocarditis.
• Lock the catheter with antibiotics. 
  • ​​​​​​​The catheter lumen is filled with antibiotic solution, and the lumen remains undisturbed for a sufficiently long time
  • No standardised dosing approach
  • One example: solutions of vancomycin or gentamicin (2mg/ml) for 8-12 hours each day, for 5-14 days
• Lock the catheter with antiseptic. 
  • ​​​​​​​Options include 70% elthanol and 0.1M hydrochloric acid