Contrast-enhanced ultrasound to determine correct central venous catheter position

We read with great interest the paper recently published by Cortellaro et al titled “Contrast enhanced ultrasound versus chest x-ray to determine correct central venous catheter position” [ ]. We agree with the authors' conclusion that contrast-enhanced ultrasound (CEUS) by itself cannot substitute chest x-ray in evaluating the catheter tip position after central venous catheter placement. Nevertheless, we would like to make some methodological comments. In a recent study [ ] combining B-mode ultrasound with CEUS, we obtained an estimate of correct catheter position in atrio-caval junction that was much more accurate than in the study of Cortellaro et al (sensitivity 96% vs 33%, specificity 93% vs 98%). We used an epigastric bicaval acoustic window, by which right atrium and both cava veins can by visualized, thus directly showing the catheter tip and CEUS exit point. By contrast Cortellaro et al used in 17% of cases the apical acoustic windows, which increased feasibility up to 100% compared with 89% in our study but did not allow the visualization of cava veins. We think direct visualization of the catheter tip or CEUS exit point is important because bubbles arrive in the right atrium even in cases of intravascular malposition, although with a short time delay from CEUS infusion, except when the catheter tip is in the inferior vena cava. In this case, however, malposition can be directly revealed by B-mode ultrasound with the epigastric bicaval acoustic window. For these reasons and the availability of B-mode ultrasound, we think visualization of the catheter tip should be regularly used in combination with CEUS.