Respiratory Variation in Central Venous Oxygen Saturation Predicts Volume Responsiveness in Hemodynamically Unstable Patients Under Mechanical Ventilation : a Prospective Cohort Study

Vascular filling represent the milestone of the treatment of hypovolemia. Its main objective is to restore vascular volume and correct perfusion issues preventing the deleterious consequences of prolonged shock.

Hypovolemia diagnosis is easy to made in obvious clinical situations such as hemorrhagic shock, deshydratation..., but there still many diagnostic difficulties regarding latent hypovolemia especially if associated with left ventricular dysfunction.

In this situations, diagnostic of hypovolemia is hard to made and other investigations are needed.

Central venous pressure (CVP) and pulmonary occlusion artery pressure (PAPO) are the mainly used parameters for indicating vascular filling but actually many studies underline their low liability in this situation.

After vascular filling, outcome measurment is needed to evaluate the efficacity of the treatment.

Outcome measurment based on hemodynamic criteria is still insufficient. In fact, tissue hypoxia persists if the cardio - respiratory system did not adapt to the metabolic needs, that's why a pathway based on therapeutic objectives like venous oxymetry is needed.

Theorically, a filling maneuver is beneficial if associated with a ScvO2 amelioration. It reflects the amelioration of cardiac output and predicts the positive responsivness to the filling test.

Inclusion criteria

• patients aged above 18 year old
• hemodynamic instability (hypotension or shock)

Exclusion criteria

• intra cardiac shunt
• severe arrythmia
• valvular regurgitation
• pacemaker
• pulmonary oedema