Fourth thoracic vertebra as landmark for depth of right internal jugular vein catheterization in infants

The carina is considered a reliable marker for the depth of right internal jugular vein catheterization in infants on chest radiograph. In adult anatomy, the carina is typically located at the level of the fifth thoracic vertebra. We are not aware of a positional relationship between infant carina and thoracic vertebrae. Thus, we evaluated that a vertebral body may be at the same level as carina and can be as radiographic landmarks for the depth of right internal jugular vein catheterization in infants. In this retrospective analysis, 108 infants (aged 1–12 months) who underwent congenital heart surgery between January 1, 2019 and June 30, 2019 were included. We analyzed the post-operative chest radiographs of those who underwent right internal jugular vein catheterization and assessed the positional relationship of the carina and vertebral bodies. We measured the vertical distance of the central venous catheter (CVC) catheter tip from the carina (below the carina 22 mm, it may be close to or into the right atrium). In total, 95 children were enrolled; The carina was located at the third thoracic vertebra in two cases (2%) and at the fourth thoracic vertebra in 93 cases (98%). The distance between the tip of CVC and the carina was 10 (4, 15) mm, and 6.3% (6 cases) had the catheter tip at more than 22 mm below the carina. Most fourth thoracic vertebrae were at the same level as the carina on chest radiographs. Therefore, it has potential as a radiographic landmark for the depth of right internal jugular vein catheterization in infants on chest radiograph.