Decrease in pulse pressure and stroke volume variations after mini-fluid challenge accurately predicts fluid...

Area of Science:

• Critical Care Medicine
• Cardiovascular Physiology
• Mechanical Ventilation

Background:

• Dynamic indices like pulse pressure variation (PPV) are often unreliable for predicting fluid responsiveness in mechanically ventilated patients with low tidal volumes.
• Accurate fluid responsiveness prediction is crucial for managing circulatory failure in critically ill patients.

Purpose of the Study:

• To evaluate the efficacy of changes in continuous cardiac index (CCI), stroke volume variation (SVV), and PPV after a small fluid challenge (100 ml) in predicting fluid responsiveness.
• To compare the predictive performance of these dynamic indices in patients ventilated with low tidal volumes.

Main Methods:

• Prospective study of 49 critically ill, sedated, mechanically ventilated patients (tidal volume <8 ml/kg ideal body weight) without arrhythmias, requiring fluid challenges.
• Measurements of CCI, SVV, and PPV before and after a 100 ml fluid challenge, followed by a 400 ml challenge.
• Fluid responsiveness defined as a ≥15% increase in cardiac index post-500 ml fluid challenge; receiver operating characteristic (ROC) curves analyzed for predictive accuracy.

Main Results:

• Twenty-two patients (45%) were responders.
• Changes in SVV (ΔSVV100) and PPV (ΔPPV100) after the 100 ml challenge showed high predictive accuracy (AUCs 0.91 and 0.92, respectively) with small grey zones (≤12%).
• Changes in CCI (ΔCCI100) had lower predictive accuracy (AUC 0.78) with a large grey zone (67%).

Conclusions:

• Changes in SVV and PPV after a 100 ml fluid challenge are accurate predictors of fluid responsiveness in critically ill patients ventilated with low tidal volumes.
• ΔSVV100 and ΔPPV100 demonstrate superior predictive performance compared to ΔCCI100 in this patient population.