[Table of Contents]

Canada Communicable Disease Report - Supplement
Volume: 23S8
December 1997

INFECTION CONTROL GUIDELINES

Preventing Infections Associated with Indwelling Intravascular Access Devices

Introduction

1. Scope of this Guideline Document

This guideline document pertains to the use of peripheral and central, venous and arterial access devices in hospital, outpatient and home care settings. It does not address angiography catheters or the use of cardiac pacemakers or devices that do not enter the vascular system, such as central nervous system shunts, hypodermoclysis, or indwelling epidural catheters. Recommendations are based primarily on studies of efficacy or effectiveness, not of cost-effectiveness. (See Appendix I for a description of the evidence-based guidelines rating system.) However, where appropriate and when supported by well-designed studies, issues about cost-effectiveness and its impact on the recommendations will be discussed. This document updates and replaces previous guidelines issued by the Laboratory Centre for Disease Control⁽¹⁾.

2. Overview of Infections Associated with Intravascular Access Devices

The use of intravascular (venous or arterial) access devices is an integral part of patient care. Indwelling vascular access devices provide a route for administering infusions such as fluids, blood products, nutrients, and intravenous medications; for procuring blood specimens; for monitoring hemodynamic function; and for maintaining emergency vascular access.

However, these devices also provide potential routes for microorganisms to enter the bloodstream (Figures 1, 2 and 3) and are a possible source of serious illness or death for patients⁽²⁾. The risk of infection associated with these devices can be minimized through adherence to appropriate infection prevention precautions⁽³⁾.

There are a number of different infections associated with these devices⁽⁴⁾ and a number of different definitions used to describe the infections (see Appendix II). Such definitions reflect what is found in the literature; they are provided for convenience only and are not recommended for use in surveillance. The surveillance definitions recommended for use are outlined in Section C.

Infections associated with intravascular devices appear to result from two main reservoirs: 1) contamination of the catheter lumen from microorganisms in the fluid path, and 2) contamination of external catheter surfaces from migration of insertion site flora along the exterior surfaces of the cannulae (Figures 1, 2 and 3). Contamination of infusion fluids has led to large epidemics of sepsis in the past, but is currently considered a rare occurrence. The majority of infecting organisms reach the cannula tip from skin flora colonizing the entry site wound or microbes contaminating the delivery system hubs from external sources (Figure 1).

The relative importance of entry site skin flora versus contamination of hubs has been a subject of considerable debate^(2,4-6). Evidence favouring hub contamination (Figure 1) as the source of infections has come from centres experiencing problems with hub connector security. It is now generally accepted that skin flora migrating from the entry site are responsible for the largest proportion of infections when catheters are used for short-term access. Hub contamination and catheter lumen colonization may be more important in long-term vascular access devices^(7,8). Therefore, aseptic technique, insertion site care, use of antimicrobial ointments, new catheter materials, choice of dressing material, and frequency of catheter replacement have been examined as infection prevention interventions. Aseptic technique, use of new catheter materials, and setting appropriate limits on the duration of device use have had the greatest impact on reducing risk.

Recommended maximum time limits for replacing intravascular therapy components have been based on three principles. First, some organisms can grow to sufficient numbers within 12 to 24 hours after contamination of an intravascular delivery system that the system then serves as a dangerous reservoir for infection. This infection was the theoretical basis for replacing intravascular systems (infusate and tubing) as often as every 24 hours.

Second, the longer a device is left in place, the higher the cumulative risk of infection. For some devices, the daily risk associated with leaving the device indwelling for another 24 hours (incidence density, see Appendix III) increases after the first few days. This observation led to recommendations to replace such devices before the daily infection risk increased and to discontinue all devices as soon as possible.

Third, in the absence of quantitative infection risk data for specific devices, policy has been based on conservative historical precedents. Prospective randomized trials have subsequently demonstrated that longer durations of use may be equally safe for certain devices when infection rates are appropriately low.

3. Definitions Recommended for Intravascular Device-Associated Infections

Many terms have been used to describe intravascular device-associated infections (IVDAI) over the years. The multitude of terms and definitions has led to confusion and difficulty comparing the results of clinical studies and comparing data between hospitals.

Contamination of infusate as a cause of IVDAI is exceedingly uncommon today, and for practical purposes definitions that are used for surveillance need not include contaminated infusate.

A clinical diagnosis of IVDAI is often very difficult, particularly when immunocompromised patient populations are involved (neutropenic cancer patients, neonates, intensive care unit patients), when blood culture results are limited, or when appropriate cultures of intravascular device (IVD) tips or IVDs have not been obtained. Many definitions used or proposed in the past have either been too rigorous for routine clinical use or have failed to incorporate microbiologic data, including semiquantitative or quantitative culture results.

The Intravascular Infection Prevention Guidelines Subcommittee, in collaboration with the Canadian Hospital Epidemiology Committee, has established a set of definitions that may be used by infection control practitioners and other health care providers responsible for IVD care, whether provided within a health care facility or in the home setting (see Tables 1 and 2 ). The definitions were established in an effort to provide practical guidelines for most clinical circumstances, including the compromised host, while acknowledging the difficulties in diagnosing IVDRIs uniformly in all circumstances, given the variations in clinical practice, extent of microbiologic investigation, and availability of IVD tips for culture.

The definitions were established after a review of existing clinical, microbiologic, and research definitions and recognize that careful examination of the vascular access site, including both inspection and palpation, is an integral part of the assessment of IVDAI. These definitions are applicable to both local (Table 1) and systemic infection (bacteremia) (Table 2), different IVDs (short term catheters, midline catheters, tunnelled catheters and totally implantable devices), and multiple potential clinical and/or microbiologic scenarios using the definite, probable, and possible infection categories. This categorization provides maximal flexibility for defining IVDAI and is aimed at fulfilling the needs of all health care providers involved in the care of IVDs. It must be emphasized that the use of all three categories (i.e., definite, probable, possible) is not required for surveillance purposes in every setting. The inclusion of the three categories will allow maximum versus minimum data collection for IVDAI for any given institution or jurisdiction, depending on its own needs. The most important goal in establishing the definitions is to achieve a common denominator for IVDAIs across the country.

The use of these standard definitions by Canadian health care providers will provide information from which benchmark and aggregate infection rates may be established for use by health care organizations that provide IVD care.

1. Local infection (Table 1)

Definite exit site infection

Purulent discharge at the exit site, either spontaneous or expressed upon palpation of the site, regardless of whether an organism is cultured from the site,

or

Erythema, tenderness, induration (any two of the three) at the exit site with serous or serosanguinous discharge, either spontaneous or expressed upon palpation, in the presence of a positive exit site culture (moderate to heavy growth of a single or predominant organism).

Probable exit site infection

Erythema, tenderness, induration (any two of the three) at the exit site with serous or serosanguinous discharge, either spontaneous or expressed upon palpation, in the absence of an exit site culture, or in the presence of an exit site culture revealing no growth or one not considered positive, as described above,

or

Erythema, tenderness, induration (any two of the three) at the exit site without any discharge (even with expression) where alternative causes (i.e., extravasation, allergy and/or contact dermatitis) cannot be ruled out.

2. Tunnel or pocket infection (Table 1)

Definite tunnel or pocket infection

Purulent discharge, either spontaneous or expressed, from a draining sinus along the path of a subcutaneously tunnelled catheter not contiguous with the exit site or from the subcutaneous pocket containing a reservoir of a totally implantable device, regardless of whether an organism is cultured from the site,

or

Purulent exudate aspirated from the subcutaneous tissues along the path of the subcutaneously tunnelled catheter and not contiguous with the exit site or from the subcutaneous pocket containing a reservoir of a totally implantable device, regardless of whether an organism is cultured from the site,

or

Erythema, tenderness, induration (any two of the three) or necrosis of the skin with serous or serosanguinous discharge, either spontaneous or expressed or aspirated from along the path of a subcutaneously tunnelled catheter not contiguous with the exit site or from the subcutaneous pocket containing a reservoir of a totally implantable device in the presence of a positive culture (moderate to heavy growth of a single or predominant organism).

Probable tunnel or pocket infection

Serous or serosanguinous discharge, either spontaneous or expressed from a draining sinus, or a serous or serosanguinous aspirate from the subcutaneous tissues along the path of the subcutaneously tunnelled catheter not contiguous with the exit site or from the subcutaneous pocket containing a reservoir of a totally implantable device in the absence of a culture or in the presence of a culture not considered positive, as described above,

or

Erythema, tenderness and induration (any two of the three) or necrosis of the skin along the path of the subcutaneously tunnelled catheter not contiguous with the exit site or from the subcutaneous pocket containing a totally implantable device with no clinical data to suggest an alternative cause, i.e., extravasation, allergy, contact dermatitis.

Possible tunnel infection (Table 1 )

Erythema, tenderness and induration (any two of the three) or necrosis of the skin along the path of a subcutaneously tunnelled catheter not contiguous with the exit site or from the subcutaneous pocket containing a totally implantable device where extravasation, allergy and/or contact dermatitis cannot be ruled out.

3. Intravascular device-related bacteremia (Table 2)

Definite intravascular device-related bacteremia

Pathological and/or microbiologic confirmation of septic thrombophlebitis from a surgically resected vein or artery within which a catheter or device had been placed, in the presence of a positive blood culture,

or

A single positive peripheral blood culture from a patient with clinical and microbiologic data disclosing no other source of the bacteremia in the presence of a semiquantitative or quantitative culture of a catheter segment (proximal or distal) from which the same organism (species, antibiogram) was isolated,

or

Quantitative blood cultures with a 10-fold or more colony count difference between blood cultures drawn from the catheter and simultaneously from a peripheral vein,

or

A single positive peripheral blood culture from a patient with isolation of the same organism (species, antibiogram) from purulent, serous or serosanguinous discharge from the catheter exit site or along the path of a subcutaneously tunnelled catheter or from the subcutaneous pocket containing a reservoir of a totally implantable device.

Probable intravascular device-related bacteremia

Two or more positive blood cultures of the same organism (species, antibiogram) from any source (peripheral or retrograde intravascular device cultures) from a patient with clinical and microbiologic data disclosing no other source for the bacteremia except the intravascular device,

or

One positive blood culture (peripheral or retrograde intravascular device cultures) of Staphylococcus aureus or Candida species from any source in a patient with clinical and microbiologic data disclosing no other source for the bacteremia except the intravascular device, or One positive blood culture from any source (peripheral or retrograde intravascular device cultures) for any organism commonly associated with intravascular device- related infection (coagulase-negative staphylococci; Bacillus species; Corynebacterium species, specially C. jeikeium; Enterococcus species; Trichophyton species; and Malassezia furfur) in an immunocompromised or neutropenic patient (neutrophils < 0.5 x 10⁹/L), a neonate, or a patient receiving total parenteral nutrition with clinical and microbiologic data disclosing no other source for the bacteremia except a centrally placed intravascular device.

Possible catheter-related bacteremia

One positive blood culture from any source (peripheral blood culture or blood culture drawn from intravascular device) of organisms other than S. aureus or Candida species in any patient not included in the list above, with clinical and microbiologic data disclosing no other source for the bacteremia except a central intravascular device.

4. Catheter colonization

Significant catheter colonization

Growth of>= 15 colony-forming units (CFU) from a catheter segment on semiquantitative culture or >= 10³ CFU/mL on quantitative culture, in the absence of inflammation.

Catheter colonization

Growth of < 15 CFU from a catheter segment on semiquantitative culture or < 10³ CFU/mL on quantitative culture, in the absence of inflammation.

Figure 1
Sources of infection of a percutaneous intravascular device^(2). (Figure is used with permission of author and publisher.)

Figure 2
Components of pressure monitoring system

Figure 3
Diagram of IV tubing containing IV fluid roller clamp, injection port and IV cannula

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