The current standard for (correct) position control of a central venous catheter (CVC) is X-ray control, which is associated with X-rays for the patient. In some clinics, radiological services are not offered "around the clock". Therefore, an alternative that is not burdensome for patients and is available on all sides would be desirable. The possibility of a sonographic CVC position control is to be investigated.

The correct position of a central venous catheter is important. Complications/failure must be detected early/immediately. In addition to the X-ray of the thorax, a position control by means of an ECG derivative (α-card derivative) is available for position control. The method is easy to perform, but an epicardial or an arterial position of the CVC cannot be detected without the use of additional imaging in case of doubt.

For the reasons mentioned above, sonography is a suitable method to show the inflow of injected 0.9% sodium chloride solution into the right atrium, which allows to conclude the correct position of the CVC.

Inclusion Criteria:

• elective insertion of a central venous catheter.

Exclusion Criteria:

• emergency insertion of a central venous catheter