Peripherally Inserted Central Catheters May Lower the Incidence of Catheter-Related Blood Stream Infections in Patients in Surgical Intensive Care Units

Abstract

Background:

Long-term central venous catheterization is associated with a higher rate of catheter-related blood stream infections (CR-BSI). It is unclear whether there is a difference in the CR-BSI rate associated with central venous catheters (CVCs) and peripherally inserted central catheters (PICCs) in long-stay patients in surgical intensive care units (SICUs). We hypothesized that PICC use reduces the rate of CR-BSI compared with use of antiseptic CVCs in these patients.

Methods:

All 121 patients admitted to our SICU for ≥14 days between July 2005 and July 2006 were included. Central venous access was maintained with an antiseptic CVC (Arrow Guard silver/chlorhexidine; n = 263) or replacement with a PICC (n = 37). Experienced residents, using maximum barrier precautions and chlorhexidine skin preparation, placed central lines; a credentialed registered nurse placed PICCs similarly. A CR-BSI was defined by semi-quantitative catheter tip cultures with ≥15 colony-forming units and at least one positive blood culture with the same organism. Multivariable regression was performed to identify predictors of CR-BSI.

Results:

There were 13 CVC infections and one PICC infection, resulting in an infection rate of 6.0/1,000 catheter-days for CVCs and 2.2/1,000 for PICCs. Infected and non-infected CVCs were in place a mean of 25 ± 11 and 16 ± 9 days, respectively. The infected PICC was in place for 19 days, whereas the remainder of the PICCs were in place a mean of 14 ± 17 days. Logistic regression demonstrated that line days (duration of catheterization) was the only independent predictor of CVC infection (p = 0.015).

Conclusion:

In this non-randomized study, PICC was associated with fewer CR-BSIs in long-stay SICU patients, although CVCs were in place longer than PICC lines. The only predictor of CVC infection was the duration the line was in place. These results suggest that minimizing the duration of central venous access and substituting PICC for CVC may reduce the incidence of CR-BSI in long-stay SICU patients.

Every year in the United States, more than five million central venous catheters (CVCs) are placed, leading to more than 80,000 cases of bacteremia [1 –4]. Catheter-related blood stream infections (CR-BSIs) lead to a prolonged intensive care unit (ICU) stay and a higher risk of death. These infections have an attributable mortality rate as high as 35% [1 –6]. Current strategies to decrease the number of infections include full barrier precautions during insertion, protocols for dressing changes, and the use of antibacterial-coated catheters. Several prospective investigations have demonstrated that antiseptic- or antibiotic-coated CVCs offer a lower incidence of CR-BSI than do traditional uncoated catheters [1,7 –9]. Despite these interventions, CR-BSI persists, with an incidence of 1.7–8% [2,4,9,10]. The National Healthcare Safety Network (NHSN) reported a national average of 2.3 infections/1,000 catheter-days in surgical ICUs (SICUs) [11]. Furthermore, a longer duration of central venous catheterization is an independent risk factor for the development of a CR-BSI [8,12,13].

Peripherally inserted central catheters (PICCs) may be a safer alternative to CVCs, especially in patients who require long-term venous access. The rate of PICC-related infection is in the range of 0.4–0.8/1,000 catheter-days, although the majority of these infections occurred in the lower-risk outpatient setting [14 –19]. Recent data indicate that in critically ill patients, the rate of PICC infections is 2.1/1,000 catheter-days [20]. Other evidence suggests that, despite the low reported incidence of PICC-related infections, there is no difference in infectious complications compared with CVCs [21 –24]. However, this evidence was presented in the context of short-term use, as patients requiring long-term access were excluded from the comparison. Currently, there are no available data comparing infectious complications of PICCs and antiseptic- or antibiotic-coated CVCs in directly critically ill surgical patients requiring long-term venous access. It is therefore unknown whether replacing a CVC with a PICC can reduce the incidence of CR-BSI in ICU patients.

The purpose of this study was to compare the rate of CVC- and PICC-related infections in long-stay (≥14 days) SICU patients. We hypothesized that a reduced rate of CR-BSI would be associated with PICC compared with antiseptic CVCs in these patients.

Patients and Methods

This study was a retrospective cohort analysis of all patients admitted to the SICU at our urban Level 1 adult trauma and tertiary-care referral center. The SICU is a closed unit staffed by six faculty members, all of whom are board-certified in surgical critical care. Monitoring indications and resuscitation endpoints, management of fluid/electrolytes, ventilator therapy, evaluation/treatment of fever/sepsis, and nutritional support are provided according to established clinical care protocols. Our SICU admits trauma, neurosurgical, and general surgical patients.

All 121 patients admitted to our SICU for a minimum of 14 days between July 2005 and July 2006 were included in the study. The median age was 47 years, and 57% were male (Table 1). Sixty-three percent were trauma patients, whereas 19% were neurosurgical and 18% general surgical. The Institutional Review Board at The University of Texas Southwestern Medical Center and Parkland Memorial Hospital approved this study.

Table 1.

Patient Characteristics

Age (years)	47 (34–62)^a
Per cent male	57
Type of admission (%)
Trauma	63
Neurosurgical	19
General surgical	18
Intensive care unit days (range)	19 (16–26)^a
Ventilator days (range)	8 (0–15)^a
APACHE II	22 (15–29)^a

Median (interquartile range).

APACHE = Acute Physiology and Chronic Health Evaluation score.

Common indications for central venous access in our SICU are central venous pressure (CVP) monitoring, pulmonary artery catheters, total parenteral nutrition (TPN), requirement for vasopressors/inotropes, and limited or no peripheral venous access. By preference of the attending physician, central venous access was maintained with an indwelling antiseptic CVC or a PICC. All CVCs were placed by experienced residents under staff supervision using a standardized protocol. Maximum barrier precautions were required for placement of all CVCs and included surgical cap and mask, sterile gown and gloves, and a full-length sterile drape. The site of insertion was chosen by the physician performing the procedure and was limited to the internal jugular or subclavian vein. The skin of the insertion site was prepared with chlorhexidine antiseptic scrub, and a sterile field was maintained throughout the procedure. An antiseptic-coated CVC (ARROWguard® silver/chlorhexidine; Arrow International Inc., Reading, PA) was placed using the Seldinger technique, and its position was verified with a chest radiograph prior to its use. All PICC lines were placed by a dedicated credentialed PICC nurse using similar maximum barrier precautions. All PICC lines contained two infusion ports and were not antibiotic or antiseptic coated. On suspicion of a catheter-related infection, the line was removed and the tip sent for analysis in the microbiology laboratory. If the indication for central venous access had not been resolved, another catheter was placed at a site remote from the original. Catheter replacement over a guide wire is strictly prohibited in our SICU.

Data were obtained from the patient's medical record, SICU nurse's log, SICU procedure log, respiratory therapy records (to identify patients on a ventilator), and the daily nurse's checklist to identify patients with a CVC or PICC in place. The type, site, and duration of central venous access were verified by viewing the daily chest radiographs and were recorded on a standardized data collection sheet. Microbiology reports were reviewed to identify any CR-BSIs, which were defined by semi-quantitative catheter tip cultures yielding ≥15 colony-forming units and at least one positive blood culture of the same organism.

The primary outcome of this study was CR-BSI associated with CVC and PICC, reported as infections per 1,000 catheter days. Secondary analysis using multivariable logistic regression was performed to identify predictors of CR-BSI by catheter type, controlling for age, sex, Acute Physiology and Chronic Health Evaluation (APACHE) II score, ICU days, ventilator days, and line days (catheter duration). Microsoft Excel (Redmond, WA) was used for all data entry and management. Statistical Analysis Software (SAS Institute, Cary, NC) was used for creation of new variables, all calculated variables, and all statistical analyses. Statistical significance was defined as α = 0.05.

Results

The median number of ICU and ventilator days were 19 and 8, respectively. Age, sex, APACHE score, admitting diagnosis, and ventilator days were similar in the CVC and PICC groups. However, the mean ICU stay was significantly longer in patients with a PICC than in those who did not have a PICC (34 vs. 21 days; p = 0.004).

Eighty-nine patients had only CVCs placed, whereas two had only PICCs, 28 had both, and two had no central venous access during their ICU course. There were 263 CVCs and 37 PICCs placed. Of the CVCs, 13 (4.9%) became infected, an infection rate of 6.0/1,000 catheter-days. This rate was not different in general surgery vs. trauma vs. neurosurgical patients. Of the 37 PICCs placed, one (2.7%) became infected, a rate of 2.2 infections/1,000 catheter-days. Sixty-three percent of the CVC infections and the one PICC infection were caused by coagulase-negative Staphylococcus (Table 2). Infected and non-infected CVCs were in place a mean of 25 ± 11 and 16 ± 9 days, respectively. The infected PICC was in place for 19 days, whereas the remainder of the catheters were in place a mean of 14 ± 17 days.

Table 2.

Predictors of Central Venous Catheter Infection

Predictor	Odds ratio (95% confidence interval)	P value
Age	1.02 (0.98, 1.06)	0.29
APACHE II	0.99 (0.92, 1.07)	0.86
Line days	1.08 (1.02, 1.15)	0.01
Ventilator days	0.98 (0.09, 1.02)	0.35
Intensive care unit days	0.99 (0.95, 1.04)	0.69

APACHE = Acute Physiology and Chronic Health Evaluation score.

Logistic regression demonstrated that the number of line days was the only independent predictor of CVC infection (p = 0.015)(Table 3). The fact that there was only a single PICC infection precluded analysis to identify predictors of PICC infection.

Table 3.

Organisms Responsible for Blood Stream Infections

Organism	% Central venous catheter infections	% Peripherally inserted central catheter infections
Coagulase-negative Staphylococcus	62	100
Enterococcus	7.5	0
Acinetobacter	7.5	0
Klebsiella	7.5	0
Pseudomonas	7.5	0
Enterococcus/methicillin-resistant S. aureus	7.5	0

Discussion

This study demonstrates that in long-stay SICU patients, PICC use resulted in a lower rate of catheter infections than CVCs, although CVCs were in place longer than PICC lines. Additionally, our data confirm previous findings that a longer duration of central venous catheterization correlates with a higher incidence of infection.

Critically ill patients in the SICU often require central venous access, particularly during the acute phase of their resuscitation. These lines allow infusion of intravenous fluid, blood products, and medications when peripheral access is limited or unobtainable. Additionally, pulmonary artery catheterization and infusion of vasoactive medications and TPN are not feasible through a peripheral vein. Central venous catheters can be placed rapidly with a low risk of mechanical complications related to placement, and their role in the management of the acutely ill patient is well defined.

Despite these advantages, CVCs harbor the potential to produce life-threatening bacterial infections. In an effort to minimize this risk, several interventions have been implemented and supported by prospective data. In several studies, the use of maximum barrier precautions during insertion of central lines has substantially reduced the incidence of CR-BSI compared with standard precautions (i.e., sterile gloves and small drape) [25 –27]. However, studies looking at other preventive strategies such as the agent used for skin preparation and the type of catheter dressing have not provided conclusive evidence to support a recommendation [28,29]. The rate of line infections in our SICU falls within the range reported in the literature but is substantially higher than the NHSN-reported national rate. All patients in our study were admitted to the SICU for a minimum of 14 days, and many required long-term central venous access. As the majority of reports include all patients with a CVC, regardless of the duration of SICU stay, the different patient populations studied may account for our higher rate of CR-BSI. Short of removing central catheters outright, it seems that only a limited number of strategies can be used proactively to reduce the rate of CVC infections. Our study suggests, however, that after the acute resuscitation phase of the illness, replacing a CVC with a PICC may reduce the risk of CR-BSI.

The PICC lines serve a purpose similar to that of the CVC in allowing the infusion of fluid and medications into a central vein or providing venous access when peripheral veins are limited. Traditionally, PICC lines have been used in patients requiring long-term access, particularly for those at home or hospitalized patients beyond the critical phase of their illness. The low infection rate makes them particularly attractive for patients recovering from a critical ailment. It seems justified, then, to question whether the benefits of PICC lines can be transferred to critically ill patients who are beyond the initial resuscitation period of their hospitalization. Our data support this idea, as the PICC infection rate was low. Although we have no established protocols to direct when and in whom PICC lines are used, they generally are placed in patients after one or more CVCs have been removed. Despite multiple prior CVCs, the rate of PICC infection was about one third that of CVC.

There are several limitations to this study. This was a non-randomized observational study with multiple data sources and therefore is subject to the potential confounders inherent in that design. In addition, there clearly was a discrepancy in the average dwelling time of CVCs and PICCs. Cultures were not obtained from all CVCs after removal, and therefore, the incidence of line colonization (based on our criteria) is unknown. Additionally, as there were no defined criteria for insertion of a CVC or a PICC, our results may be subject to selection bias. Furthermore, a long SICU stay was arbitrarily defined as 14 days, and the incidence of infectious complications in other populations of SICU patients is unknown. Finally, our study utilized data from a small, defined group of trauma or postoperative SICU patients, and our results may be invalid for the broader population of general intensive care patients.

Conclusion

In this non-randomized study, PICCs appeared to be associated with fewer CR-BSIs in long-stay SICU patients. The only predictor of CVC infection was the length of time the line was in place. This study suggests that minimizing the duration of central venous access will reduce the incidence of CR-BSI. Furthermore, substituting a PICC for a CVC may reduce the incidence of CR-BSI in long-stay SICU patients. A large prospective study will be required to validate this suggestion.

Footnotes

Author Disclosure Statement

None of the authors has any financial relationships to disclose.

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