Central Venous Line Placement in the Superior Vena Cava and the Azygos Vein: Differentiation on Posteroanterior Chest Radiographs

The purpose of this study was to determine, first, the accuracy with which radiologists reading posteroanterior chest radiographs differentiate whether a central venous line is in the superior vena cava or the azygos vein and, second, the circumstances in which radiologists may omit the lateral view to determine the position of a central venous line. Twenty-four radiologists evaluated 60 posteroanterior chest radiographs to determine the position of a central venous line in the superior vena cava or azygos vein. Investigators evaluated the appearance of the central venous lines to refine rules for determining central venous line position on a frontal radiograph and omitting the lateral view. The accuracy of posteroanterior radiography for determining central venous line position was 90% at one study location and 85.5% at the other. No central venous line in the azygos vein extended more than 10.9 mm caudal to the cephalic edge of the right main bronchus. No central venous line in the superior vena cava had a down-the-barrel or curved appearance at the caudal edge. For central venous lines extending at least 15 mm caudal to the cephalic edge of the right main bronchus and having no down-the-barrel or curved caudal appearance, categorization was nearly 100% accurate. Therefore, if desired to save radiation exposure and cost, it may be feasible to omit lateral views in radiography of patients with central venous lines extending at least 15 mm caudal to the cephalic edge of the right main bronchus in whom the caudal edge does not have a down-the-barrel or curved appearance.