The Ability of Stroke Volume Variations Obtained with Vigileo/FloTrac System to Monitor Fluid Responsiveness in Mechanically Ventilated Patients

Abstract

Respiratory variations in arterial pulse pressure (DeltaPP) are accurate predictors of fluid responsiveness in mechanically ventilated patients. The aim of our study was to assess the ability of a novel algorithm for automatic estimation of stroke volume variation (SVV) to predict fluid responsiveness in mechanically ventilated patients. We studied 25 patients referred for coronary artery bypass grafting. SVV was continuously displayed by the Vigileo/FloTrac system. All patients were under general anesthesia, mechanical ventilation and were also monitored with a pulmonary artery catheter. SVV and DeltaPP were recorded simultaneously before and after an intravascular volume expansion (VE) (500 mL hetastarch). Responders to VE were defined as patients whose cardiac index obtained using thermodilution increased by more than 15% after VE. Agreement between DeltaPP and SVV over the 50 pairs of collected data was -1.3% +/- 2.8% (mean bias +/- sd). Seventeen patients were responders to VE. A threshold DeltaPP value of 10% allowed discrimination of responders to VE with a sensitivity of 88% and a specificity of 87%. A threshold SVV value of 10% allowed discrimination of responders to VE with a sensitivity of 82% and a specificity of 88%. SVV predicts fluid responsiveness with an acceptable sensitivity and specificity and is also a potential surrogate for continuous monitoring of DeltaPP.