This is a real-word data study to evaluate the impact of CHG dressings in addition to an already ongoing catheter bundle on the incidence density rate of catheter-associated bloodstream infections (CABSIs).
A 35-bed mixed adult ICU of the Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland, a primary and referral hospital for a population of 250,000 and 1,500,000, respectively. This is the only adult ICU in the hospital and consists of five distinct units. Allocation of patients is determined by bed availability and not by a patient’s specific conditions.
All consecutive adult patients admitted to the ICU from January 2006 to December 2018 were included. Burn and ECMO patients were excluded from the analysis, as the enhanced bundle could not be systematically applied.
As the interventions were included in the measures targeted at improvement of the quality of care, with products with a patent for use in patients in Switzerland, the commission cantonale d’éthique de la recherche sur l’être humain and the institutional review board approved the study and waived the need for informed consent.
As part of the routine and mandatory data collection to comply with the “minimal data set” of the Swiss Society of Intensive Care Medicine, demographic data and SAPS II scores were collected . ICU and hospital length of stay and mortality were prospectively collected for each patient. Comorbidities were defined using definitions of the SAPS II score.
The intervention consisted of four stepwise modifications to an already established catheter bundle with progressive introduction of CHG dressings from 2007 to 2014 (Suppl Table 1).
Comparator (baseline): period A (January 2006–October 2007)
The standard of care as of January 2006 consisted of the following catheter bundle (Supplemental Table 2): (1) general infection control measures (hand hygiene, standard and isolation precautions); (2) guidelines for catheter insertion (checklist for material preparation, standardized hair removal with clippers and CHG-based skin antisepsis, maximal sterile barrier precaution); (3) handling (avoidance of needle and needleless connectors, systematic CHG disinfection of stop-cocks with new caps each time the hub is accessed); (4) maintenance (daily check for catheter necessity, signs of catheter infection, dressing integrity and need for replacement). To guarantee uniform application of the bundle, a designated physician and a designated nurse led the entire bundle and gave periodic feedback based on surveillance data [1, 7]. The designated clinical nurse specialist systematically trained ICU nurses on all elements of the bundle, including daily assessment of the dressings and face-to-face feedback and coaching. The designated physician systematically trained ICU physicians on how to apply the guidelines for insertion. This bundle was applied to all arterial and central venous lines .
Stepwise interventions: periods B through E and post-study period
To guarantee uniform implementation of the stepwise interventions (Supplemental Table 1), the dedicated clinical nurse specialist updated the institutional protocol, highlighted the changes specifically related to the use of the CHG dressings before each period, systematically trained ICU nurses to use these updated practices and completed a daily assessment of the CHG dressings with face-to-face feedback and coaching.
Period B—November 2007–Nov 2009
CHG sponge + transparent dressing on jugular and femoral CVC in all units.
Period C—December 2009–May 2011
CHG sponge + transparent dressing on all CVC and arterial catheters in all units.
Period D—June 2011–May 2013
CHG sponge + transparent dressing in three units (18 beds) and CHG gel all-in-one dressing in two units (14 beds) on all CVC and arterial catheters.
Period E—June 2013–December 2014
CHG gel all-in-one dressing in all units on all CVC and arterial lines.
Post-study period—January 2015–December 2018
CHG gel all-in-one dressing in all units on all CVC and arterial lines.
CHG sponge dressing (Biopatch®, Ethicon Inc., Somerville, NJ) covered by a transparent dressing (3M™ Tegaderm™ without disinfectant, 3 M, Saint Paul, MN)
CHG gel all-in-one dressing, containing CHG in a gel directly embedded within the transparent dressing (3 M™ Tegaderm™ CHG Chlorhexidine Gluconate I.V. Securement Dressing, 3 M, Saint Paul, MN).
Number of catheter-associated bloodstream infections (CABSIs) per 1000 catheter-days over each study period. Catheter-associated bloodstream infections were defined as either catheter-related infection or a primary bacteremia (Fig. 1). Secondary bloodstream infections were explicitly excluded .
Number of catheter-associated bloodstream infections per 1000 catheter-days by type of dressing and by type of catheter (CVC versus arterial).
Numbers of catheter-related bloodstream infections (CRBSI) and primary bacteremia over each study period, by type of dressing and by type of catheter (CVC versus arterial).
Measurement of catheter-associated bloodstream infections
A computer-based institutional surveillance program automatically identified every episode of positive blood culture linked to patients having stayed or actually staying in the ICU.
The hospital infection control staff reviewed each episode quarterly with the dedicated ICU physician. First, each episode was attributed to one the following categories: (1) community acquired (< 48 h of hospital admission), (2) hospital non-ICU acquired (< 48 h of ICU admission) and (3) hospital ICU acquired. Second, both community-acquired and hospital ICU-acquired positive blood cultures were further adjudicated to four categories: (1) catheter-related bloodstream infection, (2) primary bacteremia, (3) secondary bacteremia and (4) contamination .
Measurement of catheter-days
For each patient, the time of insertion of the catheter, time of its removal and catheter type (arterial-venous) were recorded in the computerized information system (Metavision, iMDsoft® Ltd., Tel Aviv Israel). For patients admitted with a catheter already inserted, the time of insertion was set as the time of patient ICU admission. Similarly, for patients discharged with a catheter in place, the time of discharge was set as equivalent to the time of catheter removal.
ICU catheter-days were computed as the sum of the catheter time duration (removal time minus insertion time) for every central venous catheter (including dialysis catheters and introducers sheaths for pulmonary artery catheter) and arterial catheters.
A new version of the computerized information system was implemented in January 2015. While this new version allows for a simplified computation of overall CVC-days, it precludes the analysis of data at the individual patient level. Meanwhile, other surveillance methods remain the same.
Demographics and patients characteristics
Continuous variables are reported as the mean and standard deviation (SD) or as medians and interquartile ranges [IQR]. Categorical variables are reported as frequencies and percentages.
Incidence density rates over the study periods
The numbers of CABSI, CRBSI and primary bacteremia events per 1000 catheter-days over the different periods were reported as incidence density rates (and their 95% CI). The incidence density rates were tested using a Poisson regression model (SAS 9.3 PROC GENMOD). The log of the catheter-days was used as the offset, and the dispersion parameter was estimated to help determine whether over-dispersion needed to be accounted for in the Poisson model. Each period was compared with the baseline and the preceding one. In addition, period C, where only CHG sponge was used, was compared with period E, where only CHG gel was used. Multiple comparisons for the three measures of CABSI, CRBSI and primary bacteria were done using a Bonferroni correction (p < 0.05 ÷ 3 = 0.017 was considered significant). Comparisons to period A were done using Dunnett’s method.
During period D, CHG gel dressings were introduced in two units (14 beds), whereas CHG sponge dressings were maintained in the three other units (18 beds). This allowed for a contemporaneous comparison of the effect of both dressings using CABSI, CRBSI and primary bacteremia as outcomes. The comparisons were carried out using the same Poisson regression model.
Individual data and catheter-days were gathered from each individual ICU stay (n = 19,423) including the 111 CABSIs (70 CRBSIs and 41 primary bacteremia events). We used a Cox proportional hazards regression model (SAS 9.3 PROC PHREG), with catheter-days representing the time factor and CABSI as the event of interest. Models were adjusted on age at ICU entry, SAPS 2 and duration of mechanical ventilation.