Do ScvO₂ variations induced by passive leg raising predict fluid responsiveness? A prospective study.

Area of Science:

• Critical Care Medicine
• Cardiovascular Surgery
• Hemodynamic Monitoring

Background:

• Fluid responsiveness (FR) assessment is crucial for managing mechanically ventilated patients.
• Passive leg raising (PLR) is a dynamic method to assess fluid responsiveness.
• Central venous oxygen saturation (ScvO2) reflects oxygen delivery and consumption balance.

Purpose of the Study:

• To evaluate if ScvO2 variations induced by PLR can predict FR in mechanically ventilated patients post-cardiac surgery.
• To determine the diagnostic accuracy of ScvO2 changes during PLR for predicting fluid responders.

Main Methods:

• A prospective monocentric study involving 33 postoperative cardiac surgery patients requiring mechanical ventilation.
• Continuous monitoring of ScvO2 and left ventricular outflow tract velocity time integral (VTI) during PLR and volume expansion (VE).
• Fluid responders were defined by a VTI increase ≥15% after VE (500 ml saline).

Main Results:

• A >4% increase in ScvO2 during PLR predicted a VTI response with 93% sensitivity and 94% specificity (AUC 0.92).
• ScvO2 variations during PLR distinguished fluid responders from non-responders with 87% sensitivity and 89% specificity (AUC 0.89).
• ScvO2 increased significantly during PLR in fluid responders (9 ± 4%) but not in non-responders.

Conclusions:

• ScvO2 variation induced by PLR is a reliable and minimally invasive predictor of fluid responsiveness.
• This method is valuable for bedside fluid management in mechanically ventilated, critically ill cardiac surgery patients.
• PLR-induced ScvO2 changes offer a practical approach to optimize fluid therapy in intensive care settings.