Central Venous Pressure (CVP) Changes do Not Predict Preload Unresponsiveness

Passive leg raising (PLR) is routinely used to predict preload responsiveness in critically ill patients. However, real-time measurements of cardiac output are required to assess its effects. Some authors have suggested that in fluid non-responders, central venous pressure (CVP) increased markedly. By analogy with the CVP rules proposed by Weill et al to assess a fluid challenge, it has been hypothesized that an increase in CVP ≥ 5 mmHg during PLR can predict preload unresponsiveness.

Objective Investigation of whether an increase in CVP ≥ 5 mmHg during PLR predict preload unresponsiveness diagnosed by the absence of increase in velocity-time integral (VTI) of the flow in the left ventricular outflow tract by more than 10% (4).

Methods Critically ill patients with a central venous catheter in place and for whom the physician decided to test preload responsiveness by PLR were prospectively included. Transthoracic echocardiography was performed to obtain VTI. The CVP and VTI were measured before and during PLR.