[Central venous pressure. Validity, informative value and correct measurement].

The trends in central venous pressure (CVP) are more informative than the isolated values. The CVP should always be evaluated in the context of the patient's clinical condition. It indicates the relationship between circulating blood volume and the capacity of the heart at a given time. In the ideal situation CVP reflects cardiac preload and there are many variables that influence its numerical value as well as its interpretation. The CVP is a meaningful parameter if it is measured correctly. For accurate measurement the transducer must be zeroed and leveled to a correct external reference level for the right atrium. Only a CVP measured at the end of expiration can be compared on condition that the catheter is placed correctly in the central venous system.