Figure 18. To measure central venous pressure (CVP), a catheter is placed in an arm vein and advanced through the vein to just outside of the right atrium, where all the blood from the body enters the heart. A transducer is placed in the armpit at the same height as where the catheter tip is placed outside the right atrium. Pressure travels from the catheter tip to the transducer. Ther transducer transforms the pressure into a voltage signal that the CVP recording unit can recognize.