Central intravascular pressure measurements: when should we believe them?

With the widespread use of invasive hemodynamic monitoring of the pulmonary circulation to aid in diagnosis and therapy of cardiac and respiratory failure, shock, and pulmonary hypertension, diagnostic radiologists have become accustomed to interpreting chest radiographs in the context of measured intrathoracic intravascular pressures. Unfortunately, errors in measurement and interpretation of these pressures are common. Perhaps the most difficult aspect of invasive hemodynamic monitoring is the interpretation of measured pressures in the context of a variety of clinical circumstances and disease states, some of which may dramatically alter the usual relationship between the pulmonary artery wedge pressure and left ventricular preload. Without detailed information about the techniques used to obtain these measurements and the clinical status of the patient at the time that they are made, the measurements should not be used as a standard against which clinical and radiographic findings are judged.