Estimation of Internal Jugular Vein Central Venous Pressure (CVP) by Ultrasound

Objectives: 1. To study the validity and reliability of estimation of the central venous pressure by measurement of internal jugular vein size using 2-dimensional ultrasound. 2. To evaluate the correlation of internal jugular vein cross sectional area and central venous pressure. Methods: 1. The study design is prospective observational study. 2. We will include all patients scheduled for cardiac surgery in Siriraj Hospital and record both internal jugular size using 2-dimensional ultrasound just before central venous catheter insertion. The central venous pressure will be recorded and the ultrasound picture will be measured. 3. The data will be analyzed.