Reducing catheter-related bloodstream infections using Lean Six Sigma methodology

Abstract

Background

Central venous catheters (CVC) are used for dialysis in end-stage renal disease patients, presenting a significant risk for Catheter-Related Bloodstream Infections (CRBSI). While Lean Six Sigma has been effective in reducing CRBSI, its efficacy outside intensive care units (ICU) remains less explored. This study aims to evaluate the effectiveness of Lean Six Sigma in mitigating CRBSI risks among non-ICU hemodialysis patients.

Methods

The study was conducted in a nephrology department, focusing on patients undergoing hemodialysis with temporary CVC from February to December 2021. The Lean Six Sigma method, using Define-Measure-Analyze-Improve-Control (DMAIC) methodology, was implemented in 2022 to reduce CRBSI incidence. The 2021 CRBSI rate served as the benchmark, with a goal to reduce it by the end of 2022. Value-stream mapping, Fishbone Diagrams, and Root Cause Analysis identified potential CRBSI causes. After implementing targeted improvements, CRBSI rates before and after the intervention were compared.

Results

The Lean Six Sigma method significantly decreased CRBSI incidence from 12.79 to 2.32 per 1,000 catheter-days following the implementation of targeted interventions ($\:{\chi\:}^{2}$=4.60, P = 0.05). This improvement was observed comparing February-December 2021 with January-December 2022.

Conclusion

The findings demonstrate the effectiveness of the Lean Six Sigma method in non-ICU settings, suggesting broader applicability in hemodialysis patient care.

Background

Hemodialysis remains the primary treatment for patients with end-stage renal disease, with an autogenous arteriovenous fistula being the preferred access method, followed by vascular grafts, and ultimately, central venous catheters (CVC) [1]. Despite this, research shows that over 60% of hemodialysis patients use a CVC as the vascular access for their first dialysis [2]. Vascular access failure is a leading cause of end-stage renal disease patients’ hospitalization, contributing to prolonged stays [3]. Catheter-Related Bloodstream Infections (CRBSI) are severe complications for hemodialysis patients with CVC [4]. In patients with end-stage renal failure, the infection mortality rate is between 12% and 22%, with 75% of these infections caused by CRBSI [5] and associated with prolonged hospital stays [6]. These infections increased medication use and medical costs. CRBSI are considered preventable [7], with rates in the US reported between 2.5 and 6.6 cases per 1,000 CVC days [8,9,10,11,12], while the Centers for Disease Control and Prevention’s reported rate of 0.6 per 1,000 catheter days [13]. CRBSI rates in developing countries are expected to be higher due to disparities in medical resources [14]. Rates in China could exceed those in the US, as seen at the Guangdong Provincial Hospital of Chinese Medicine in 2021, with an incidence of 12.79 per 1,000 catheter days in the nephrology department.

Addressing CRBSI reduction is crucial. Lean Six Sigma has been effective in healthcare, enhancing efficiency and lower hospital-acquired infections rates [15,16,17]. However, its use in reducing CRBSI, particularly outside intensive care units (ICU), is underexplored. Utilizing Lean tools like Value-stream mapping and Standardized Work, St. Luke’s Episcopal Hospital achieved a 97% reduction in blood coolers return delays [18]. In Spain, hospitals improved physiotherapists’ effective treatment time and reduced inventory costs using Lean tools like Kanban and 5 S (sort, set, shine, standardize and sustain) [19]. In China, hospitals increased urine sample collection accuracy and reduced pharmacy error reporting using Lean tools like Fishbone Diagrams and 5 S [20, 21].

This project at the Guangdong Provincial Hospital of Chinese Medicine aimed to identify factors affecting the CRBSI incidence and evaluate Lean Six Sigma’s effectiveness using Define-Measure-Analyze-Improve-Control (DMAIC) methodology and tools like Fishbone Diagrams and Kanban. The goal was to demonstrate Lean Six Sigma’s potential in reducing CRBSI in non-ICU settings, offering hospitals strategies to minimize infection risks and showcasing its applicability in healthcare improvement.

Methods

Setting and participants

This study was conducted in the nephrology ward of the Guangdong Provincial Hospital of Chinese Medicine, Da De Road main campus. In this study, all CVCs were temporary and inserted into the right internal jugular vein. The skin disinfectant used was Amriodine II, and the lock solution was a heparin saline solution, consisting of heparin sodium injection (2 ml at 12,500 units) and sodium chloride injection (10 ml at 0.09 g). The clinical definition of CRBSI was adopted from the standards issued by the National Health Commission of the PRC. CRBSI refers to bacteremia or fungemia in hospitalized patients with an intravascular catheter or within 48 h of catheter removal, accompanied by signs of infection such as fever (> 38 °C), chills, or hypotension, with no other identifiable source of infection besides the catheter. Laboratory microbiological tests confirm CRBSI if positive cultures for bacteria or fungi are found in peripheral blood, or if the same type of pathogen with identical antibiotic sensitivity results is cultured from both the catheter tip and peripheral blood [22].

The CRBSI rate was defined as the incidence rate of CRBSI per unit time, expressed as the number of cases per thousand days of CVC placement. Historical data from patients who received hemodialysis with temporary CVCs from February to December 2021 were collected retrospectively to determine the CRBSI incidence for 2021. The Lean Six Sigma was executed using the DMAIC method from January to December 2022 to evaluate its effectiveness in reducing the CRBSI incidence. The CRBSI rate was calculated as [23]:

$${\large\begin{aligned}&CRBSI\,rate \\&= \frac{Number\,of\,CRBSI\,cases }{Total\,number\,of\,days\,of\,CVC\,placement\,for\, patients\,during\,the\,same\,period}\\&\times 1000\textperthousand\end{aligned}}$$

For example, a CRBSI rate of m$\textperthousand$ means m per 1,000 catheter days.

Program description

The Lean Six Sigma method was executed using the DMAIC methodology, elaborated upon in the following sections.

Define: identify the problem

In this stage, the problem, scope, and objectives of the project were clearly defined, and a multidisciplinary team was established. The team included the head of the hospital’s infection control office, representatives from the patient service center, nursing department, and the heads of the nephrology and hemodialysis departments, including doctors and nurses (Table 4 in Appendix). The primary problem identified was the incidence of CRBSI in the nephrology department in 2021. The project’s goal was to reduce the CRBSI incidence below 2021 levels by the end of 2022. Additionally, the project explored the impact of improvement measures on the duration of antibiotic use among patients. Value-stream mapping (Figure 3 in Appendix) was created to provide a clearer understanding of the overall process.

Measure: data collection

The main purpose of this phase was to determine the current incidence of CRBSI. Historical data collected retrospectively from February to December 2021 revealed that among 30 nephrology patients totaling 391 CVC days, there were 5 cases of infection (CRBSI rate = 12.79‰). The secondary objective of this stage was to identify potential root causes for CRBSI. Data collection included demographic information, CVC usage details, CRBSI occurrence, and assessments of patients’ physical functions.

Analyze: cause analysis

The core of this stage focused on verifying the root causes of CRBSI. Root Cause Analysis was conducted for each CRBSI case, and a checklist of potential causes was developed. To visualize potential reasons for CRBSI, a Fishbone Diagram was created (Fig. 1).

Fig. 1

Fishbone diagram of potential causes of CRBSI

To identify the causes, the team designed a hemodialysis catheter maintenance checklist based on the 2021 Infusion Therapy Standards of Practice published by the Infusion Nursing Society [24]. The checklist focused on catheterization conditions, catheter and connector types, maintenance status, and pathogen sampling, assessing the quality of CVC maintenance. During on-site observation from March $\:{1}^{st}$ to March $\:{31}^{st}$, 30 hemodialysis catheter maintenance checklists and supervision forms were collected. Pareto charts analysis (Fig. 2) indicates that the main CRBSI causes were related to dressing changes frequency, insufficient skin disinfection, and catheter puncture site assessment.

Fig. 2

Pareto chart of catheter maintenance checklists of hemodialysis CVC (upper) and Pareto chart of catheter maintenance supervision forms of hemodialysis CVC (lower)

To ensure objective and accurate cause analysis, the multidisciplinary team observed catheterization processes on site and conducted discussions focused on predefined criteria, such as adherence to standard operating procedures, to reaffirm the primary causes of CRBSI.

Improve: implement action

The purpose of this phase was to identify and implement solutions to the root causes identified earlier. Utilizing the Fishbone Diagram and Pareto chart, the multidisciplinary team brainstormed targeted improvement measures, detailed in Table 1. These interventions were implemented throughout 2022. The CRBSI incidence was then recalculated, and the effectiveness of the measures was analyzed by comparing the CRBSI before and after the intervention.

Table 1 Root cause analysis and corresponding improvement measures

Control: continuous monitoring

After applying Lean Six Sigma, a plan was needed to ensure the sustainable improvements. The team prioritized embedding enhanced practices within the department’s culture by organizing targeted training sessions and assessments. A Kanban, a type of visual project management tool that uses cards to represent tasks and columns to represent stages of work [25], was established to visually track monthly CRBSI, enhancing staff awareness and motivation to maintain improved procedures. The team also conducted real-time monitoring through the information system, addressing any deviations or issues promptly, fostering ongoing improvement.

Tools

The Lean Six Sigma tools used in this study include project charter, Value-stream mapping, Root Cause Analysis, Fishbone Diagram, Pareto analysis, and Kanban.

Statistical analysis

Data analysis was conducted using SPSS version 29.0 (SPSS Inc., Chicago, IL, USA). CRBSI rates before and after the intervention were compared using Fisher’s Exact Test. The number of days with combined antimicrobial drug use and the number of days with dual antibiotics use were compared between two periods using the t-test.P ≤ 0.05 was considered statistically significant.

Results

Comparison of baseline data before and after the intervention revealed no statistically significant differences between the two cohorts (Table 2).

Table 2 Comparison of baseline data before and after intervention

The CRBSI at the Guangdong Provincial Hospital of Chinese Medicine’s Nephrology Department main campus was 12.79 per 1,000 catheter days in 2021, highlighting a significant issue. Analysis using Pareto charts and Fishbone Diagrams identified materials and maintenance as key factors impacting CRBSI incidence. Targeted improvement measures addressing these root causes were implemented throughout 2022. The post-intervention analysis included 57 patients, with only 2 cases of CRBSI reported, demonstrating a significant reduction in the incidence rate to 2.32 per 1,000 catheter days after the intervention ($\:{\chi\:}^{2}$=4.60, P ≤ 0.05) (Table 3).

Table 3 Comparison of CRBSI before and after intervention

Discussion

This study examined the impact of applying the Lean Six Sigma approach, executed using DMAIC methodology, to reduce CRBSI in the Nephrology Department of the Guangdong Provincial Hospital of Chinese Medicine, Da De Road main campus. In 2021, the CRBSI was 12.79 per 1,000 catheter days, much higher than the Centers for Disease Control and Prevention’s national pooled mean of 0.6 per 1,000 catheter days [11]. Reducing CRBSI can decrease mortality, improve patient safety, and enhance patient satisfaction.

Different Lean tools were used at each DMAIC stage, facilitating goal definition, data collection, cause analysis, improvement implementation, and maintenance. The Define phase identified the research problem and visually outlined CVC management. The Measure phase reported a CRBSI incidence of 12.79 per 1,000 catheter days. In the Analyze phase, Fishbone Diagrams, Pareto charts, and Root Cause Analysis identified potential causes. After implementing targeted improvements, the CRBSI significantly reduced to 2.32 per 1,000 catheter days. This aligns with a Southwest Minnesota ICU study where the DMAIC method eradicated Central Line-Associated Bloodstream Infections. After the implementation of the DMAIC method, no Central Line-Associated Bloodstream Infections events were reported in that ICU [26]. In the Control phase, measures such as Kanban were used to monitor and maintain results. The study showed that Lean Six Sigma effectively reduces CRBSI.

Previous studies have demonstrated Lean Six Sigma’s effectiveness in optimizing patient medication processes, medical procedures, and operating room workflows. This study extends its efficacy to non-ICU settings, providing real-world evidence for Lean Six Sigma’s broader applicability in healthcare.

The study acknowledges the potential influence of the Hawthorne effect, where subjects may modify their behavior due to being observed, potentially impacting the results [27]. Our study was limited by a small sample size. Future research could extend Lean Six Sigma methodologies to other healthcare branches and departments to increase the sample size, thereby a more comprehensive evaluation of the effectiveness of this method in reducing CRBSI rates and could generate findings that are broadly applicable.

Overall, this study provides new evidence supporting Lean Six Sigma’s effectiveness in reducing the CRBSI in non-ICU departments, offering insights into broader infection control strategies in healthcare.

Conclusion

In conclusion, applying the Lean Six Sigma method in the Nephrology Department of the Guangdong Provincial Hospital of Chinese Medicine significantly reduced the CRBSI. Additionally, the Lean tools used provide valuable strategies for hospital administrators and quality management personnel to control infections, improve and maintain clinical care quality.

Appendix

Table 4 Description of project charter

Fig. 3

Value-stream mapping of CVC management in hemodialysis patients