Once an independent clinical decision has been reached to place an SCVC by the ED attending physician, the study investigators will be contacted to enroll the patient. Patients will be randomly assigned to receive either landmark or ultrasound guided SCVC placement. In the ultrasound guidance group, a two person technique will be utilized in which the ultrasound machine will be operated by one of the investigating physicians, and the catheter will be placed by the ED physician caring for the patient. The investigators will employ real time ultrasound guidance using both the transverse and longitudinal views to help direct the needle to the vein. Once the vascular structures are identified on ultrasound by the investigating physician, the physician placing the SCVC will be directed to puncture the skin at the optimal location as determined by the investigating physician. Ultrasound will be used throughout the entire procedure to cannulate the underlying vein. In the landmark group, the SCVC will be placed using anatomic landmarks to locate the puncture site by the physicians working clinically in the ED. The Seldinger technique used for SCVC placement is the same for both the landmark and ultrasound guided approaches.