Anatomical Landmark Method for Paediatric Port Catheter Tip Positioning

Port catheter placement procedures were performed under ultrasound guidance. To ensure correct positioning of the catheter tip, a length estimation method based on anatomical landmarks was used. This method was developed by reviewing contrast-enhanced chest computed tomography images of pediatric patients without thoracic deformities. In these images, the ideal catheter tip position was identified just above the junction of the superior vena cava and the right atrium. When this point was projected onto the chest wall, it most often corresponded to the upper border of the junction between the right third rib and the sternum. In clinical practice, the distance between the vascular puncture site and this anatomical landmark was measured on the skin using a ruler, and the catheter length was adjusted accordingly before placement.

For each patient, two catheter length measurements were obtained: one using anatomical landmarks and one using intracavitary electrocardiography. Although both measurements were recorded for comparison, the catheter was trimmed and placed according to the anatomical landmark method. Intracavitary electrocardiography is a safe and cost-effective method that allows real-time confirmation of catheter tip position. In this study, a modified approach was created using standard anesthesia monitors. After venous access was established, the proximal end of the sterile guidewire was connected to an electrocardiogram electrode placed on the right shoulder. As the guidewire was advanced, changes in the cardiac P-wave were monitored continuously. The point of maximum P-wave amplitude, corresponding to the junction of the superior vena cava and the right atrium, was identified, and the corresponding intravascular length was recorded.