Introduction

Critical care patients often require the use of intravascular catheters for their treatment, but these devices also increase the risk of catheter-related bloodstream infections (CRBs) [1]. One of the leading causes of CRBs is contamination during catheter insertion due to suboptimal skin antisepsis or failure to maintain aseptic conditions [2,3,4]. Ultrasound guidance (USG) is a recommended technique for catheter insertion as it allows for real-time visualization of the vessels during needle placement and travel, thereby improving accuracy and reducing complications [5,6,7,8,9,10,11]. However, CRBs have been reported due to the use of contaminated ultrasound gel [12, 13], and recent studies have associated the use of USG with an increased risk of CRBs [8]. However, the three studies described by Buetti et al., being retrospective and non-observational, the association between the use of USG for CVC placement and the increase in the incidence of CVC-related bacteremias could not be discussed in the context of all catheter insertion conditions. Although essential measures for optimal US-guided central venous catheter (CVC) insertion are well-established [10], the extent to which these measures are implemented in practice is unknown. To address this issue, we conducted an inventory of current practices regarding the use of USG during catheter insertion. We collected data through a questionnaire completed by intensivists responsible for device placement and conducted an observational study of their practices when inserting catheters using USG, with a specific focus on identifying breaches of the surgical asepsis required during catheter insertion.

Methods

Between January 1st and July 31st, 2022, we conducted a two-part study among French intensivists. In the first part, we asked intensivists to describe their use of USG during the insertion of CVCs, dialysis catheters (DCs), arterial catheters (ACs), peripheral intravenous central catheters (PICClines) and MIDlines in ICU patients. The questionnaire collected information on the types of catheters inserted with USG, insertion sites, frequency of USG use, training, and the use of a procedure (Additional file 1). The questionnaires were distributed by the local infection control teams after providing information about the study. The second part of the study was an observational study. Local infection control teams observed intensivists placing catheters using USG using a standardized grid that included data on skin antisepsis, sterile gloving, type of gels used, use of a sterile protective sheath to cover the probe, and hand hygiene. We excluded emergency situations (Additional file 2). We analyzed the questionnaires and observation sheets at a national level, based on available recommendations [8,9,10,11] (Table 1).

Table 1 Specific expectations for intensivists using US guidance, practices evaluated and results obtained
Full size table

Results

A total of 26 ICUs located in distinct hospitals took part in the study.

Questionnaire analysis

111 intensivists, including 26 residents (23.4%), completed the questionnaire (Table 1; Additional file 3: Tables S1 and S2). Among them, 94.6% reported using USG for catheter insertion, with the highest adoption rate for CVCs (93.7%), DCs (82.0%), and ACs (80.2%). USG use is systematic for CVCs and DCs while more variable for ACs. Of the 105 intensivists using USG, 56.2% received training on its use, as part of initial/continuing education (57.6%), or provided by a commercial company (22.0%) or by colleagues (20.3%); 17.1% of the intensivists benefited from specific recommendations for catheter insertion that take into account the use of USG. Before skin antisepsis, 93.3% of intensivists mark the insertion site using USG, with 27.6% using a sterile sheath to cover the probe and 29.6% using a sterile gel, although it is not necessary at this stage. During catheter insertion, all intensivists use a sterile sheath, 96.2% use single-dose sterile gel, and 17.9% report contact between the tip of the needle and the sheath, occurring systematically (n = 5), frequently (n = 2), sometimes (n = 10), or rarely (n = 5).

Observational study (Tables 1)

36 intensivists, including 16 residents (44.4%), were observed inserting catheters [23 CVCs (63.9%), 7 MID lines (19.4%), 3 DCs (8.3%), 2 PICC lines (5.5%), and one AC (2.8%)]. Of the intensivists, 44.4% had received training on USG, mostly during their initial/continuing education (68.7%). Before skin antisepsis, 58.3% marked the insertion site using USG, with 28.6% using a sterile sheath and 23.8% using sterile gel. Compliance with skin antisepsis recommendations was satisfactory [i.e., skin cleaning (94.1%), application of alcoholic antiseptic solution (94.4%) with a sterile compress/applicator (100%), adherence to antiseptic drying time (100%)], except for the use of a 2% chlorhexidine alcoholic solution (36.1%) and hand hygiene compliance (63.0%). For catheter insertion, a sterile sheath covering the probe and cable was used in 88.9% of cases, and single-dose sterile gel was applied in all cases. However, only 33.3% of intensivists complied with surgical hand disinfection and/or wearing sterile gloves. In 19.4% of cases, the tip of the needle came into contact with the sheath, and one intensivist handled the US system without changing their gloves after the incident (2.8%) (Table 2).

Table 2 Distribution of the 36 intensivists according to hand hygiene (HH) and gloving compliance in the course of the catheter insertion, according to the occurrence of an insertion site marking and the participation of the operator to the skin antisepsis (each row corresponds to a specific observation sequence described in the successive columns
Full size table

Discussion

The use of USG has become a standard practice for CVC insertion [9]. However, the role of USG in the risk of CRBs is still debated. While it was not found to be a significant factor in some RCTs [14,15,16,17], a retrospective analysis of 3 RCTs found an association between USG and an increased risk of CRB (HR = 2.21, 95% CI 1.17–4.16) [8]. It is important to note that most randomized controlled trials did not specifically assess the infectious risk associated with USG [6,7,8]. Therefore, a thorough assessment of the infectious risk associated with the use of USG during CVC insertion is warranted.

Our study, conducted across 26 ICUs, utilized a questionnaire designed to elicit information on the intensivists’ use of USG during catheter insertion, and direct observation of intensivists inserting catheters. The data obtained from these two methods were concordant and complementary, shedding new light on the practice of US-guided catheter insertion. They first showed that USG is commonly used for inserting CVCs and DCs, and to a lesser extent for ACs, in line with current guidelines [9,10,11, 18]. However, only 50% of intensivists have received USG training, and most have not been given recommendations for catheter insertion that incorporate USG use. To promote best practices, regular USG training should be provided to intensivists, along with specific guidelines accessible to all ICUs [8]. Training should be conducted through simulation sessions that encompass both technical training for the use of ultrasound guidance to assist in catheter placement and the incorporation of hygiene rules to ensure strict asepsis during the procedure. To instill hygiene rules in the early stages of training for ultrasound guidance use, infection control specialists should be integrated into the teams responsible for scenario preparation. Our research has also identified potential deviations from strict aseptic technique. First, there are concerns related to the handling of the US system during catheter insertion and direct contact between the sheath and the catheter, as reported by intensivists and observed by infection control teams. Second, we have identified practices that do not ensure surgical aseptic conditions during insertion. In particular, among the intensivists who mark the insertion site, 33% use unnecessary sterile sheaths and single-dose sterile gel. This practice may result in the contamination of the sheath with the patient's skin flora, as skin antisepsis has not yet been performed, and if the sheath is not changed before catheter insertion, it can potentially contaminate the insertion site and the needle during catheter insertion. In addition, at the time of catheter insertion, intensivists follow the main recommendations to ensure a priori rigorous aseptic conditions (i.e., using a sterile sheath to protect the US probe, sterile gel, and sterile gloves), but for one-third of the intensivists, the sterile gloves are worn from the beginning of the skin antisepsis phase and are not changed before starting catheter insertion. Given these conditions, we suggest that the gloves, which are likely to be contaminated during the antisepsis phase, could serve as a source of catheter contamination during insertion. We propose raising awareness among intensivists about the infectious risks associated with the hasty use of sterile devices long before catheter insertion.

Our study has several limitations that should be acknowledged. First, our observations may not be fully representative of all intensivists. The study was conducted on a voluntary basis, and therefore, the participating hospitals and practitioners may have been particularly concerned with infectious risks, potentially leading to selection bias. We also cannot provide a response rate for our survey because we do not know the number of French intensivists performing central catheter insertions. Second, there may have been observation bias, particularly due to the Hawthorne effect. However, it should be noted that all French regions were represented, and the proportion of private and public hospitals was similar to that observed in France. Overall, these limitations are more likely to have minimized the extent of noncompliance with infection control policies than to have increased it.

Conclusion

To prevent an increase in infections associated with USG during central catheter insertion, it is necessary to implement interventions aimed at ensuring compliance with measures to prevent catheter-related bloodstream infections, taking into account the specifics of catheter placement using USG.