Background
The ultrasound-guided insertion technique for central venous catheterization is widely used, as it is reported to increase the success rate and decrease the rate of mechanical complications such as arterial mispuncture, pneumothrax, and hematoma when compared to the anatomical landmark-guided insertion technique [
1‐
3].
Catheter-related bloodstream infections (CRBSIs) are serious complications associated with central venous catheterization. They can result in increased costs and risk of mortality [
4‐
7]. The incidence of CRBSIs was reported to be 2.2 to 2.79 infections per 1000 catheter days [
8,
9]. An increase in the success rate of the first attempt and shortening of the procedural duration by ultrasound guidance can result in protection from contamination of catheters as well as the insertion site during insertion, and ultrasound-guided central venous catheterization is recommended for preventing CRBSIs in pediatric intensive care units [
10]. Furthermore, several guidelines also recommend the use of ultrasonography, which minimizes contamination by reducing the number of attempts and breakdown of the aseptic technique and decreases the rate of CRBSIs in adults and children [
11‐
14]. However, the clinical evidence remains unclear.
A recent post hoc analysis of three randomized controlled trials demonstrated that the ultrasound-guided insertion technique was associated with an increased risk of CRBSIs [
15]. However, the patients were not randomized according to the insertion technique. Therefore, the association between ultrasound-guided central venous catheterization and CRBSIs remains unclear. Ultrasound guidance may reduce the number of attempts but may increase contamination during the process of manipulation. Although ultrasound-guided central venous catheterization is mandatory today, we hypothesized that it would be worthwhile to evaluate the efficacy of ultrasound guidance on the incidence of CRBSIs. Hence, we conducted a systematic review and meta-analysis to determine the value of ultrasound guidance in preventing CRBSIs and catheter colonization associated with central venous catheterization.
Discussion
This meta-analysis of randomized controlled trials compared the efficacy of ultrasound-guided and anatomical landmark-guided central venous catheterization with respect to CRBSIs as well as catheter colonization. From the available data, this study suggests that the ultrasound-guided insertion technique might be associated with a lower incidence of CRBSIs than anatomical landmark-guided insertion techniques.
Numerous studies have compared the outcomes of insertion success and early complication rates between ultrasound-guided and anatomical landmark-guided central venous catheterization. However, most studies did not focus on CRBSIs, which have been reportedly associated with increased mortality [
4‐
6], and patients would certainly benefit from reducing the incidence of this complication. In our literature search, only four randomized controlled trials compared the outcome of CRBSIs between ultrasound-guided and anatomical landmark-guided central venous catheterization. Two studies [
20,
22] were excluded from the meta-analysis because there were no events in either arm, and this meta-analysis did not show the efficacy of ultrasound-guided central venous catheterization on the incidence of CRBSIs. Although the point estimate of RR is 0.46, the wide CI including 1 suggests the decreased certainty. Regarding catheter colonization, only one study [
20] was included in the meta-analysis, and no association was observed between ultrasound-guided central venous catheterization and catheter colonization.
Two observational studies have compared the incidence of CRBSIs between ultrasound-guided and anatomical landmark-guided central venous catheterization; however, the difference was not statistically significant [
25,
26]. Buetti et al. performed a post hoc analysis of three randomized controlled trials and demonstrated that the ultrasound-guided insertion technique was associated with an increased risk of CRBSIs (hazard ratio, 2.21; 95% CI, 1.17–4.16; p = 0.014) [
15]. In that study, uncertainty about ultrasound techniques, including hygiene compliance, was stated as a limitation. Furthermore, as these studies randomized the patients according to the catheter insertion sites, skin asepsis, and dressings and not the insertion technique, the results may have been influenced by several confounding factors, especially because ultrasonographic guidance tends to be used in difficult or severe cases.
Regarding catheter insertion sites, one multi-center randomized controlled trial reported that the incidence of catheter colonization was higher in the femoral vein than in the internal jugular vein, while the incidence of CRBSIs was not different between the two veins [
27]. Of the four studies included in our meta-analysis, one study adopted the internal jugular or femoral vein and patients were stratified according to the insertion site. In the three other studies, the insertion site was the internal jugular vein. Therefore, the insertion site itself is unlikely to have had much effect on the results.
This study had some limitations. First, only two studies and a relatively small number of patients were included in this meta-analysis, and significant heterogeneity was observed among the included studies on CRBSIs. The results of this study should be interpreted with caution. Second, only one included study focused on CRBSIs as a primary outcome. Third, only critically ill patients were included in the study. Finally, all the included studies detailed the use of povidone-iodine and not chlorhexidine for sterilization; therefore, caution should be exercised when extrapolating to the current practice of central venous catheterization.
Conclusion
In conclusion, ultrasound-guided central venous catheterization might reduce the incidence of CRBSIs. However, only four studies were included in this systematic review. Additional randomized controlled trials are necessary to evaluate the effect of ultrasound-guided central venous catheterization on the incidence of CRBSIs and catheter colonization.
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