How to prevent central line infections

Use sterile technique and remove them ASAP. What else?

Oct 16, 2023

Central venous catheters (CVCs, or central lines) are necessary devices to provide dialysis or deliver certain therapies (vasopressors, hypertonic saline, chemotherapy, IV nutrition, etc). Almost 5 million CVCs are placed per year in the U.S. alone.

As a direct portal to the bloodstream, central lines pose an inherent infection risk. Most catheter-related bloodstream infections are preventable, but this demands consistent and meticulous attention to simple (but easily overlooked) measures during line placement and dressing care.

How Often Do Central Lines Become Infected?

At most U.S. hospitals, between roughly one and four central line-associated bloodstream infections (CLABSI) occur per 1,000 days with a central line in place (catheter-days).

For central lines left in place 10 days, that translates to about 1 infection for every 25 to 100 people. That’s a wide range, and the difference is explained largely by adherence to infection prevention practices.

Most CLABSIs are Preventable, and It Matters

The strongest evidence for the potential to reduce central line bloodstream infections came from the Michigan Keystone ICU project.

CLABSI rates were about 2.5 per 1,000 catheter-days in a 2004 analysis across Michigan (or about 1 infection for every 40 people with a CVC for 10 days). CLABSI rates were reduced by two-thirds (to 0.76 per 1,000 catheter-days, or about 1 infection per 130 people with a CVC for 10 days), 10 years after implementation of a state-wide infection prevention bundle.

As effective practices spread (and changes in reporting occurred), nationwide rates of CLABSI in the U.S. also decreased from 3.64 to 1.65 per 1,000 central-line days between 2001 and 2009.

CLABSI rates then increased dramatically during the Covid-19 pandemic. This is presumed to have been due to extreme strains on healthcare teams resulting in a decline in adherence with infection prevention. The subsequent trajectory of CLABSI rates remains to be seen (as nationwide data reporting has not yet recovered to its pre-Covid state).

Central line infections result in excess mortality, hospital stays, and cost (although the magnitude of all three are debated). More than half of central line infections now occur outside the ICU, and continuous attention to CLABSI prevention is required regardless of patient location or acuity.

What Causes Central Line Infections?

Infection by bacteria may occur during central line placement from a break in sterile conditions; these infections are believed to usually manifest within a week.

After the line placement, infection may occur from a variety of mechanisms:

Contamination of insertion site due to inadequate dressing-site decontamination (which should be done frequently)
Non-sterile manipulation of the catheter hubs, allowing bacteria to create a biofilm in the lumen(s) of the CVC
Contamination of the catheter by hematogenous spread from another site of infection (endocarditis, abscess, etc). This is the least common cause of CVC infections.

Prevention thus focuses on mitigating contamination of central lines in these scenarios.

Checklists and Central Line Kits

Checklists ensure consistency and reduce the likelihood of deviation from sterile conditions during central line placement. Checklists were an essential component of the Michigan-wide project that demonstrated a large reduction in CVC infection rates.

Experienced proceduralists may have internalized most or all checklist steps into muscle memory and habit, but it’s worth using one until 100% adherence becomes almost automatic, and maybe after that, too.

Download the central line checklist from John Hopkins here. Some of the important elements for infection prevention include:

Clean hands: alcohol-based gel is preferred unless hands are soiled
Prep site with chlorhexidine (at least 2%) and allow it to dry
Maintain sterile technique with cap, mask, gown and gloves
Everyone entering the room wears a cap and mask
Drape patient from head-to-toe (this is superior to smaller drapes)
Flush all catheter lumens with sterile saline and clamp the unused lumens
Maintain control of guidewire throughout procedure (it can easily become contaminated)
Aspirate blood from all lumens and apply sterile caps
Clean site with chlorhexidine and apply sterile dressing
Apply sterile caps to all hubs

Besides making life easier, “procedure carts” loaded with everything required for central line placement (preferably in one large sterile-packed bundle) might also help prevent CVC infections, by reducing procedure time and/or breaks in sterile technique for supplies not at hand.

Where Should a Central Line Be Placed to Prevent Infection?

In the ICU, central lines placed in the subclavian vein generally have the lowest rates of CVC infection. The skin over the subclavian site is the least likely to be contaminated at the time of insertion, and the subclavian insertion site dressing is easier to keep clean.

However, subclavian lines also carry the highest risk for pneumothorax. In a large randomized trial, subclavian CVC placement by experienced proceduralists (and their supervised trainees) had a 1.5% rate of pneumothorax requiring a chest tube — about one in every 67 patients.

Most central lines in the ICU are placed under ultrasound guidance in the internal jugular vein, representing a perceived middle ground of risk for pneumothorax and infection prevention.

The traditional perception that femoral CVCs are extremely infection-prone may be exaggerated. In the aforementioned randomized trial, femoral vein CVCs were no more likely to be infected than internal jugular or subclavian CVCs. In studies done outside the ICU, femoral CVCs haven’t shown a significantly higher rate of infection compared to other sites. Certainly, the femoral site is more difficult to keep clean.

Are PICCs Less Infection-Prone than Other Central Lines?

Peripherally-inserted central catheters (PICCs) are inserted through the skin into an arm vein, and advanced under ultrasound into large central veins.

A 2006 analysis showed much lower rates of CLABSI with PICC lines, compared to conventional central venous catheters (0.5 per 1,000 catheter-days). Other analyses have concluded that for hospitalized patients, the rates of CLABSI from PICCs are about equal to CVCs.

More recently, multiple centers have reported case series also suggesting PICC lines have lower infection risks. However, most of these are small and subject to publication bias.

CLABSI rates are probably lower with PICCs in the outpatient setting, but there’s no recent robust data comparing PICCs to CVCs in the inpatient setting.

Remove All Central Lines as Soon as Feasible

All central lines are increasingly prone to infection the longer they’re left in place, and should be removed as soon as they are no longer necessary.

PICCs in particular are commonly left in place for prolonged periods—either for convenience, to reduce patient discomfort, or because their status as a central line is overlooked. At least one center has warned of morbidity and mortality resulting from prolonged PICC use.

Daily rounding on all patients with central lines should include discussion of ongoing needs for central venous access, with consideration of central line removal.

Should Central Lines Be Regularly Changed?

The likelihood of intraluminal colonization and dressing contamination increase with time. At some centers, central lines are regularly replaced (e.g., every week) with the intention of preventing CLABSI.

There’s no randomized trial data to support this practice, and the Healthcare Infection Control Practices Advisory Committee (HICPAC, whose recommendations CDC generally adopts) has advised against routine replacement of central lines as an infection prevention strategy.

How to Manage Central Line Dressings

Many CLABSIs occur due to contamination of the skin around or under the central line dressing. Careful dressing care with frequent decontamination and appropriate dressing changes can usually prevent this.

Numerous specific recommendations are available here: search the document for “dressings” or “Catheter Site Dressing Regimens”.

Other Methods to Prevent CLABSI

Catheters impregnated with antibiotics (minocycline–rifampin) or chlorhexidine reduce catheter colonization and CVC-related bloodstream infections. These catheters are not yet widely used, likely due to their increased cost.

Daily chlorhexidine bathing has shown inconsistent benefits in randomized trials, but a meta-analysis suggested bathing reduces CLABSI, especially gram-positive infections.

Antiseptic-impregnated hubs and caps may prevent CLABSI. These aren’t universally used because they haven’t been shown to be more effective than good catheter care, which always includes manually disinfecting the caps and hubs.

Only impregnated catheters have consistently been shown efficacious at reducing catheter-related bloodstream infections in randomized trials.

CLABSI vs CRBSI: What’s the Difference?

Central line-associated bloodstream infection (CLABSI) is an epidemiologic term. CLABSIs are considered to occur when any patient with a central line develops positive blood cultures (bacteremia) from a blood culture drawn more than 48 hours after the central line was placed. There’s no attempt to establish the infection came from the CVC.

Catheter-related bloodstream infection (CRABSI) is a clinical term. CRBSI is bacteremia considered to be due to the central line (or other intravenous catheter), after consideration of all the relevant clinical information in the case.

For example, a patient who presented with shock and mitral regurgitation, received a central line for vasopressors on day 0, and was found to have bacteremia from blood cultures drawn on day 3 due to endocarditis would have a CLABSI, but not a CRBSI. (All patients with CRBSIs are also classified as CLABSIs.)

CLABSI has the advantage of being easily and consistently applied to large numbers of patients using data extraction alone. It will necessarily include some patients whose bacteremia is not related to their central line. Over many cases analyzed, that small excess is believed to be consistent enough (as a proportion of total cases) that the rates and changes in incidence of actual infections (CRBSI) can be accurately inferred from trends in the data.

That should be true when analyzing thousands of cases; smaller data sets (like those tracking CLABSI rates at a single hospital) are more subject to imprecision from random error.

Because CRBSI have been shown to be highly preventable, since 2008 they’ve been included in the list of hospital-acquired infections for which Medicare won’t pay hospitals. Many states have instituted mandatory reporting of CLABSI. These measures have dramatically increased hospital administrators’ attention to CLABSI rates, and have likely had an effect of reducing actual rates of CRBSI.

The effects of these financial and institutional pressures on clinician behavior (e.g., reduction in the rate of blood cultures obtained on patients with central lines and fevers; propensity toward classifying bloodstream infections as present on admission, etc.) continue to be evaluated.