Can Capillary Refill Time Variation During Passive Leg Raising Predict Fluid Responsiveness

Fluid responsiveness in a context of circulatory failure can be assessed by different way. Microcirculatory evaluation to assess fluid responsiveness could be interesting, but the available device are expensive and the analysis are delayed. Capillary refill time (CRT) is hampered by its variability. The investigators have developed a method to standardize the pressure, the length of compression and a computerized analysis to calculate the capillary refill time. This method enables accurate measure of CRT.

The investigators will study if CRT variation induced by a passive leg raising (PLR) can predict CRT after a 500 ml Fluid Load.

About thirty patients in circulatory failure with a continuous cardiac output monitoring for whom, the attending physician has decided a fluid load, will be included. hemodynamic parameters (arterial pressure, venous pressure, cardiac output), metabolic parameters (arterial and venous blood gas and lactate), microcirculatory parameters (assessed by sublingual video-microscopy) and capillary refill time measured on the thorax and on the gingival area will be recorded. Data collection will be made before and after a passive leg raising and after a 500 ml fluid load of crystalloids.

Patients will be aposteriori sorted in two groups: responders and non responders, defined by the reduction of CRT after the fluid load. The diagnosis ability of the CRT variation after PLR to predict in which group each patient is classified will be investigate and receiver operative characteristic curve will be built. These results will be compared to the metabolic response, the macrocirculatory response, and the microcirculatory response.