Key Point

Using bedside chest radiographs may not be appropriate to detect intra-atrial central venous catheter positioning.

Using bedside chest x-ray (CXR) alone may not be sufficient to accurately identify intra-atrial central venous catheter (CVC) tip position, reported Melanie Wirsing, MD, of the Department of Anesthesiology and Intensive Care Medicine at Friedrich Schiller University of Jena, Germany, and colleagues. “However, it is still the most trusted method to identify other CVC malpositions or complications such as pneumothorax,” stated the authors in the September Chest.

“Above all, it is accessible to most patients in contrast to TEE [transesophageal echocardiography], which is, however, the superior method for assessing CVC tip position in relation to the RA [right atrium].” The vertical distance from the CVC tip to the carina (TC-distance) may be a valid marker for intra-atrial CVC placement, they further suggested.

In this prospective study, 213 patients slated for elective cardiac surgery at a university hospital were randomly assigned to undergo right or left internal jugular vein catheterization. CVC placement was guided using ECG, and TEE was used as a reference tool to assess CVC positioning. A total of 212 CVC tips were visible by TEE, and the films were then independently surveyed by two anesthetists.

Using CXR films obtained at the patients’ bedside in the ICU, one senior radiologist (ie, in charge of the ICU for more than 10 years) and two radiologists in their fifth year of training reviewed the radiographs of each patient postoperatively, unaware that the procedure had been ECG-guided and blinded to the results of the TEE assessment. “We hypothesized that their level of experience would influence the technique of interpretation and therefore the accuracy,” the investigators stated.

The reviewers were asked to assess the quality of the radiographs (ie, rotation and contrast) and evaluate the position of the CVC tip (intra-atrial or extra-atrial), documenting the radiologic markers used to support their decision, without restrictions on the type of markers used. They were also asked to identify the carina and the right tracheobronchial angle and to measure the TC-distance.

Of the 212 chest radiographs evaluated, five CVCs (2.4%) had intra-atrial placement and 207 CVCs had extra-atrial placement. The first radiologist in training correctly determined extra-atrial CVC placement with a 44% specificity and intra-atrial placement with a 60% sensitivity, and the second radiologist in training, with a 60% specificity and 40% sensitivity. Their primary criteria for determining tip position were a caudal position of CVC tip in relation to the atrial outline and a caudal position below the carina. The senior radiologist correctly identified extra-atrial placement with a 94% specificity and intra-atrial placement with 40% sensitivity, using intra-atrial placement of CVC tip at a location caudal to the atrial contour (ie, within the heart silhouette) as his primary criterion.

Although high specificity was achieved by the senior radiologist, sensitivity of CVC tip positioning was poor for all three radiologists. For the senior radiologist, “Only 14% of all CVCs determined to be intra-atrial actually end in the RA,” the authors said. “As a consequence, one had to conclude that the bedside CXR is inadequate to distinguish between intra-atrial and extra-atrial tip positions.”

Radiographic landmarks such as the right tracheobronchial angle could not be used, because it was only seen in 68 CXRs (32%), the authors reported. The carina, however, was visible in 203 radiographs (96%). “An explanation may be that the carina projects onto homogeneous tissue (mediastinal tissue), whereas the right tracheobronchial angle projects onto different tissue qualities (lung, vessels, and mediastinal tissue),” the researchers suggested.

TC-distance could be evaluated in 200 CXRs; the optimal cutoff value was assessed as 55 mm. The study authors concluded that this marker could serve as a simple tool to help inexperienced radiologists determine CVC tip position.

—Frederique H. Theuvenin

Suggested Reading
Wirsing M, Schummer C, Neumann R, et al. Is traditional reading of the bedside chest radiograph appropriate to detect intraatrial central venous catheter position? Chest. 2008;134(3):527-533.

Return to table of contents