During the study, the patient should be in a supine position with the head elevation above 30°. For the initial contrast injection, the upper arm should be elevated above the patient's head because of the larger amount of contrast injected as compared to the lower arm. The contrast will fill the superior vena cava, descending aorta, bilateral brachiocephalic veins, and subclavian veins. Contrast filling of bilateral subclavian veins serves as a landmark for the optimal placement of the tip of the venous access tube (Fig. 1e, f).
Definitive placement of the tip is confirmed by the absence of opacification in the main or intermediate bronchus. Correct catheter position is confirmed by the presence of opacification in the descending aorta at the level of the carina, and absence of opacification in the left and right upper lobe bronchi. In the absence of these findings, the study must be repeated until these are seen.
A review for tip position should be performed in the true anteroposterior chest radiograph once the correct position of the tip is established. If the tip is not at the crossing of the SVC with the right main bronchus, it should be advanced, the small catheter balloon inflated and then deflated for a maximum of 2 seconds. If the tip is not correctly placed, it will no longer be inflated with contrast material. As the patient end-expiratory breath-holds, the tip will be visible in the PA radiograph. If not, the short term study is repeated.
If the tip of the venous access catheter is in the SVC, it is not recommended that a chest radiograph is done for confirmation of position because the venous access catheter will not be visible. A chest radiograph can be done to determine the length of the venous access catheter, and if necessary, the catheter or radiopaque marker of a venous access catheter can be removed and replaced with a longer-length venous access catheter.
On chest radiographs, the distal SVC projects over the right main/intermediate bronchus. Thus, placement of the tip at the crossing of the SVC and right main bronchus will provide adequate positioning (Fig. 1a, b). During flow confirmation studies, complete filling of the port chamber with contrast material should be seen. Contrast material fills the venous tube without leakage, coming out of the tip to flow freely in the SVC (Fig. 1c, d). d2c66b5586