An evidence-based approach to central venous catheter management to prevent catheter-related infection in critically ill patients

Heparin versus 0.9% sodium chloride locking for prevention of occlusion in central venous catheters in adults

BACKGROUND

Intermittent locking of central venous catheters (CVCs) is undertaken to help maintain their patency and performance. There are systematic variations in care: some practitioners use heparin (at different concentrations), whilst others use 0.9% sodium chloride (normal saline). This review looks at the effectiveness and safety of intermittent locking with heparin compared to normal saline, to see if the evidence establishes whether one is better than the other. This is an update of an earlier Cochrane Review.

OBJECTIVES

To evaluate the benefits and harms of intermittent locking of CVCs with heparin versus normal saline in adults to prevent occlusion.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was 20 October 2021.

SELECTION CRITERIA

We included randomised controlled trials in adults ≥ 18 years of age with a CVC that compared intermittent locking with heparin at any concentration versus normal saline. We excluded studies on infants and children from this review.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were occlusion of CVCs and duration of catheter patency. Our secondary outcomes were CVC-related bloodstream infections and CVC-related colonisation, mortality, haemorrhage, heparin-induced thrombocytopaenia, CVC-related thrombosis, number of additional CVC insertions, abnormality of coagulation profile and allergic reactions to heparin. We used GRADE to assess the certainty of evidence for each outcome.

MAIN RESULTS

We identified one new RCT with 30 participants for this update. We included a total of 12 RCTs with 2422 participants. Data for meta-analysis were available from all RCTs. We noted differences in methods used by the included studies and variation in heparin concentrations (10 to 5000 IU/mL), time to follow-up (1 to 251.8 days), and the unit of analysis used (participant, catheter, line access). Five studies included ICU (intensive care unit) patients, two studies included oncology patients, and the remaining studies included miscellaneous patients (chronic kidney disease, haemodialysis, home care patients, etc.). Primary outcomes Overall, combined results may show fewer occlusions with heparin compared to normal saline but this is uncertain (risk ratio (RR) 0.70, 95% confidence interval (CI) 0.51 to 0.95; 10 studies; 1672 participants; low-certainty evidence). We pooled studies that used participant or catheter as the unit of analysis. We carried out subgroup analysis by unit of analysis. No clear differences were detected after testing for subgroup differences (P = 0.23). We found no clear evidence of a difference in the duration of catheter patency with heparin compared to normal saline (mean difference (MD) 0.44 days, 95% CI -0.10 to 0.99; 6 studies; 1788 participants; low-certainty evidence). Secondary outcomes We found no clear evidence of a difference in the following outcomes: CVC-related bloodstream infections (RR 0.66, 95% CI 0.08 to 5.80; 3 studies; 1127 participants; very low-certainty evidence); mortality (RR 0.76, 95% CI 0.44 to 1.31; 3 studies; 1100 participants; very low-certainty evidence); haemorrhage (RR 1.54, 95% CI 0.41 to 5.74; 3 studies; 1197 participants; very low-certainty evidence); or heparin-induced thrombocytopaenia (RR 0.21, 95% CI 0.01 to 4.27; 3 studies; 443 participants; very low-certainty evidence). The main reasons for downgrading the certainty of evidence for the primary and secondary outcomes were unclear allocation concealment, suspicion of publication bias, imprecision and inconsistency.

AUTHORS' CONCLUSIONS

Given the low-certainty evidence, we are uncertain whether intermittent locking with heparin results in fewer central venous catheter occlusions than intermittent locking with normal saline in adults. Low-certainty evidence suggests that heparin may have little or no effect on catheter patency duration. Although we found no evidence of differences in safety (CVC-related bloodstream infections, mortality, or haemorrhage), the combined studies were not powered to detect rare adverse events such as heparin-induced thrombocytopaenia. Further research conducted over longer periods would reduce the current uncertainties.

Heparin versus 0.9% sodium chloride locking for prevention of occlusion in central venous catheters in adults

BACKGROUND

Intermittent locking of central venous catheters (CVCs) is undertaken to help maintain their patency. There are systematic variations in care: some practitioners use heparin (at different concentrations), whilst others use 0.9% NaCl (normal saline). This review looks at the effectiveness and safety of intermittent locking with heparin compared to 0.9% NaCl to see if the evidence establishes whether one is better than the other. This work is an update of a review first published in 2014.

OBJECTIVES

To assess the effectiveness and safety of intermittent locking of CVCs with heparin versus normal saline (NS) in adults to prevent occlusion.

SEARCH METHODS

The Cochrane Vascular Information Specialist (CIS) searched the Specialised Register (last searched 11 June 2018) and the Cochrane Central Register of Controlled Trials (CENTRAL; 2018, Issue 5). Searches were also carried out in MEDLINE, Embase, CINAHL, and clinical trials databases (11 June 2018).

SELECTION CRITERIA

We included randomised controlled trials in adults ≥ 18 years of age with a CVC that compared intermittent locking with heparin at any concentration versus NS. We applied no restriction on language.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, assessed quality, and extracted data. We contacted trial authors to retrieve additional information, when necessary. We carried out statistical analysis using Review Manager 5 and assessed the overall quality of the evidence supporting assessed outcomes using GRADE. We carried out prespecified subgroup analysis.

MAIN RESULTS

We identified five new studies for this update (six prior studies were included in the original review), bringing the number of eligible studies to 11, with a total of 2392 participants. We noted differences in methods used by the included studies and variation in heparin concentrations (10 to 5000 IU/mL), time to follow-up (1 to 251.8 days), and the unit of analysis used (participant, catheter, line access).Combined results from these studies showed fewer occlusions with heparin than with NS (risk ratio (RR) 0.70, 95% confidence interval (CI) 0.51 to 0.95; P = 0.02; 1672 participants; 1025 catheters from 10 studies; I² = 14%) and provided very low-quality evidence.We carried out subgroup analysis by unit of analysis (testing for subgroup differences (P = 0.23; I² = 30.3%). When the unit of analysis was the participant, results show no clear differences in all occlusions between heparin and NS (RR 0.79, 95% CI 0.58 to 1.08; P = 0.15; 1672 participants; seven studies). Subgroup analysis using the catheter as the unit of analysis shows fewer occlusions with heparin use (RR 0.53, 95% CI 0.29 to 0.95; P = 0.03; 1025 catheters; three studies). When the unit of analysis was line access, results show no clear differences in occlusions between heparin and NS (RR 1.08, 95% CI 0.84 to 1.40; 770 line accesses; one study).We found no clear differences in the duration of catheter patency (mean difference (MD) 0.44 days, 95% CI -0.10 to 0.99; P = 0.11; 1036 participants; 752 catheters; six studies; low-quality evidence).We found no clear evidence of a difference in the following: CVC-related sepsis (RR 0.74, 95% CI 0.03 to 19.54; P = 0.86; 1097 participants; two studies; low-quality evidence); mortality (RR 0.76, 95% CI 0.44 to 1.31; P = 0.33; 1100 participants; three studies; low-quality evidence); haemorrhage at any site (RR 1.32, 95% CI 0.57 to 3.07; P = 0.52; 1245 participants; four studies; moderate-quality evidence); or heparin-induced thrombocytopaenia (RR 0.21, 95% CI 0.01 to 4.27; P = 0.31; 443 participants; three studies; low-quality evidence).The main reasons for downgrading the quality of evidence were unclear allocation concealment, imprecision, and suspicion of publication bias.

AUTHORS' CONCLUSIONS

Given the very low quality of the evidence, we are uncertain whether intermittent locking with heparin results in fewer occlusions than intermittent locking with NS. Low-quality evidence suggests that heparin may have little or no effect on catheter patency. Although we found no evidence of differences in safety (sepsis, mortality, or haemorrhage), the combined trials are not powered to detect rare adverse events such as heparin-induced thrombocytopaenia.

Heparin versus 0.9% sodium chloride intermittent flushing for prevention of occlusion in central venous catheters in adults

BACKGROUND

Heparin intermittent flushing is a standard practice in the maintenance of patency in central venous catheters. However, we could find no systematic review examining its effectiveness and safety.

OBJECTIVES

To assess the effectiveness of intermittent flushing with heparin versus 0.9% sodium chloride (normal saline) solution in adults with central venous catheters in terms of prevention of occlusion and overall benefits versus harms.

SEARCH METHODS

The Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched December 2013) and the Cochrane Central Register of Controlled Trials (CENTRAL) (2013, Issue 11). Searches were also carried out in MEDLINE, EMBASE, CINAHL and clinical trials databases (December 2013).

SELECTION CRITERIA

Randomised controlled trials (RCTs) in adults 18 years of age and older with a central venous catheter (CVC) in which intermittent flushing with heparin (any dose with or without other drugs) was compared with 0.9% normal saline were included. No restriction on language was applied.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, assessed trial quality and extracted data. Trial authors were contacted to retrieve additional information, when necessary.

MAIN RESULTS

Six eligible studies with a total of 1433 participants were included. The heparin concentrations used in these studies were very different (10-5000 IU/mL), and follow-up varied from 20 days to 180 days. The overall risk of bias in the studies was low. The quality of the evidence ranged from very low to moderate for the main outcomes (occlusion of CVC, duration of catheter patency, CVC-related sepsis, mortality and haemorrhage at any site).Combined findings from three trials in which the unit of analysis was the catheter suggest that heparin was associated with reduced CVC occlusion rates (risk ratio (RR) 0.53, 95% confidence interval (CI) 0.29 to 0.94). However, no clear evidence of a similar effect was found when the results of two studies in which the unit of analysis was the participant were combined (RR 0.21, 95% CI 0.03 to 1.70), nor when findings were derived from one study, which considered total line accesses (RR 1.08, 95% CI 0.84 to 1.40). Furthermore, results for other estimated effects were found to be imprecise and compatible with benefit and harm: catheter duration in days (mean difference (MD) 0.41, 95% CI -1.29 to 2.12), CVC-related thrombosis (RR 1.22, 95% CI 0.74 to 1.99), CVC-related sepsis (RR 1.02, 95% CI 0.34 to 3.03), mortality (RR 0.77, 95% CI 0.45 to 1.32) and haemorrhage at any site (RR 1.37, 95% CI 0.49 to 3.85).

AUTHORS' CONCLUSIONS

We found no conclusive evidence of important differences when heparin intermittent flushing was compared with 0.9% normal saline flushing for central venous catheter maintenance in terms of efficacy or safety. As heparin is more expensive than normal saline, our findings challenge its continued use in CVC flushing outside the context of clinical trials.

A prospective, randomized trial of rifampicin-minocycline-coated and silver-platinum-carbon-impregnated central venous catheters*

OBJECTIVE

Central venous catheters are the predominant cause of nosocomial bacteremia; however, the effectiveness of different antimicrobial central venous catheters remains uncertain. We compared the infection rate of silver-platinum-carbon (SPC)-impregnated catheters with rifampicin-minocycline (RM)-coated catheters.

DESIGN

A large, single-center, prospective randomized study.

SETTING

Twenty-two-bed adult general intensive care unit in a large tertiary metropolitan hospital in Brisbane, Australia (2000-2001).

PATIENTS

Consecutive series of all central venous catheterizations in intensive care unit patients.

INTERVENTIONS

Randomization, concealment, and blinding were carefully performed. Catheter insertion and care were performed according to published guidelines. Blood cultures were taken at central venous catheter removal, and catheter-tip cultures were performed by both roll-plate and sonication techniques. Pulsed field gel electrophoresis was used to establish shared clonal origin for matched isolates.

MEASUREMENTS AND MAIN RESULTS

Central venous catheter colonization and catheter-related bloodstream infection were determined with a blinded technique using the evaluation of the extensive microbiological and clinical data collected and a rigorous classification system. Six hundred forty-six central venous catheters (RM 319, SPC 327) were inserted, and 574 (89%) were microbiologically evaluable. Colonization rates were lower for the RM catheters than SPC catheters (25 of 280, 8.9%; 43 of 294, 14.6%; p=.039). A Kaplan-Meier analysis that included catheter time in situ did not quite achieve statistical significance (p=.055). Catheter-related bloodstream infection was infrequent for both catheter-types (RM 4, 1.4%; SPC 5, 1.7%).

CONCLUSIONS

The SPC catheter is a clinically effective antimicrobial catheter; however, the RM catheter had a lower colonization rate. Both catheter types had low rates of catheter-related bloodstream infection. These results indicate that future studies will require similar rigorous methodology and thousands of central venous catheters to demonstrate differences in catheter-related bloodstream infection rates.

New approaches to the treatment of sepsis

The clinical spectrum of sepsis, severe sepsis, and septic shock is responsible for a growing number of deaths and excessive health care expenditures. Until recently, despite multiple clinical trials, no intervention provided a beneficial outcome in septic patients. Within the last 2 years, studies that involved drotrecogin alfa (activated), corticosteroid therapy, and early goal-directed therapy showed efficacy in those with severe sepsis and septic shock. These results have provided optimism for reducing sepsis-related mortality.

A prospective, randomized study in critically ill patients using the Oligon Vantex® catheter

Microbial colonization and the incidence of catheter-related bloodstream infections (CR-BSI) associated with Oligon Vantex silver central venous catheters (CVC) in critically ill patients were determined. A prospective, randomized, controlled 17-month trial was carried out in an intensive care unit (ICU). All patients requiring a triple-lumen CVC for four days or longer were enrolled. Patients were randomized to receive a standard polyurethane CVC or an Oligon Vantex silver CVC. Before removal of the catheter either due to discharge from the ICU or suspected infection, blood for cultures was taken via the CVC and a peripheral site. Skin and hub swabs and catheter-tips were also cultured. Two hundred and six catheters, 103 in both groups, were evaluated. In the control group (CG) 45/103 (44%) and in the silver group (SG) 30/103 (29%) were colonized or had a CR-BSI (P=0.04). The SG was less likely to be colonized than the CG when the catheter remained in situ for eight days or less (P=0.03) or over 15 days (P=0.01); a second or subsequent catheter was present in the same patient (P=0.002), or if the CVC was placed in the internal jugular vein (P=0.05). Multivariate logistic-regression showed predisposing factors for catheter colonization were jugular and femoral sites, second or subsequent catheter, and being a member of the CG. CR-BSI occurred in five cases (four in CG). Rates of CR-BSI per 1000 catheter-days in the CG were 2.8 and in the SG, 0.8 (P<0.001). The Oligon Vantex silver catheter reduced the incidence of catheter-colonization and may decrease the risk of CR-BSI.

Central venous catheters: infection and patient susceptibility

Infection is a major cause of morbidity in haemodialysis patients, of which between 25% and 50% of infections are related to vascular access, most commonly central venous catheters (CVCs) (Kessler et al, 1993). The morbidity associated with CVC infection provides a focus for research investigation, as there is limited knowledge available in relation to physiological and psychological parameters that may increase the probability of haemodialysis patients acquiring a CVC-related infection. This study explores these issues and discusses various factors that influence infection. It then describes how organisms which live on and inside our bodies can become parasitic, thus causing an infection. The precautions taken by healthcare professionals to reduce colonization and infection are enumerated, and the value of considering patients' physiological and psychological parameters alongside the more traditional extrinsic infection control approaches is discussed.

Can we achieve consensus on central venous catheter-related infections?

Central venous catheter-related bacteraemia is a substantial and preventable source of iatrogenic morbidity and mortality. A single episode of catheter-related bacteraemia has an estimated cost of A$50,000, with an attributable mortality between 10 and 35%. Catheter colonization is diagnosed with standard culture techniques. Diagnostic criteria for catheter-related bacteraemia include the results of cultures from the catheter tip, the peripheral blood and other possible sites of infection. The presence of clinical symptoms and subsequent defervescence may assist in making the diagnosis. This review explores the existing definitions of catheter-related infections and proposes a new and more rigorous classification with criteria for definite, probable and possible catheter-related bacteraemia. The authors hope that this classification will enhance the interpretation of the literature and the planning of new investigations. Infection rates can be reduced by appropriate site selection, adequate skin preparation, sterile technique and appropriate dressings. Decreased manipulation of administration sets, with more careful technique and less frequent set replacement, may reduce hub contamination. Infection rates increase with the duration in situ of the catheter, however are not reduced by regular scheduled catheter replacement or guide-wire exchanges. A range of antimicrobial catheter materials and coatings are under investigation, some of which are effective in reducing the rate of catheter-related bacteraemia. Chorhexidine-silver sulphadiazine and rifampicin-minocycline are the best studied combinations to date. Further developments are expected, although none are likely to be as effective as not inserting or removing the central venous catheter when it is not required.