central venous pressure

Central venous pressure (CVP) is the pressure in the large veins just as they empty into the right atrium—essentially the pressure at the ‘front door’ of the heart’s filling side. It is normally quite low, just a few mmHg, because this is the low-pressure end of the circulation.

CVP reflects the interplay between how much blood is returning to the heart and how readily the right heart can accept and forward it. A low CVP often suggests the tank is under-filled (for example from dehydration or bleeding), while a high CVP can mean the right heart is struggling, or that there is fluid overload or obstruction to filling. It is measured directly through a catheter whose tip sits in a great vein near the right atrium, and estimated non-invasively by inspecting the jugular venous pressure in the neck.

Once used as a simple gauge of ‘volume status,’ CVP is now interpreted more cautiously: a single number correlates poorly with whether a patient actually needs fluids, because so many factors (heart function, chest pressure, vessel tone) influence it. It is most useful watched as a trend and combined with the rest of the clinical picture.