Central venous pressure

Overview
Central venous pressure (CVP) describes the pressure of blood in the thoracic vena cava, near the right atrium of the heart. CVP reflects the amount of blood returning to the heart and the ability of the heart to pump the blood into the arterial system.

It is a good approximation of right atrial pressure, which is a major determinant of right ventricular end diastolic volume. (However, there can be exceptions in some cases.)

Measurement
Normal CVP can be measured from two points of reference:


 * Sternum: 0-5 cm H2O
 * Midaxillary line: 5-10 cm H2O

CVP can be measured by connecting the patient's central venous catheter to a special infusion set which is connected to a small diameter water column. If the water column is calibrated properly the height of the column indicates the CVP.

In most progressive intensive care units in the U.S., specialized monitors are available to continuously measure CVP as well as other hemodynamic values.

Factors which increase CVP include:

 * Hypervolemia
 * forced exhalation
 * Tension pneumothorax
 * Heart failure
 * Pleural effusion
 * Decreased cardiac output
 * Cardiac tamponade

Factors which decrease CVP include:

 * Hypovolemia
 * Deep inhalation