[How reliable is non-invasive measuring of central venous pressure using the Doppler ultrasound probe?]

The venous flow to the heart can be heard by an ultrasound device. This blood flow ceases at a certain intrathoracic pressure (VAP). By 219 pressure readings VAP could be proved to correlate significantly with the central venous pressure (rs = 0.748). In 90.4% of the measurements the difference was less than 5 cm H2O.