Inclusion Criteria:  undergoing a surgical procedure requiring a CVC Patients must be at least 18 years of age. Patients that have given informed written consent.  -  Exclusion Criteria:  Patients that do not speak or understand Norwegian language. Skin disease or infection affecting the whole-body surface or within the area of examination. Patients with untreated coagulopathy Known vascular abnormality Any reason why, in the opinion of the investigators, the patient should not participate. Subject participates in a potentially confounding drug or device trial during the course of the study.