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

Background Dynamic indices, such as pulse pressure variation (PPV), are inaccurate predictors of fluid responsiveness in mechanically ventilated patients with low tidal volume. This study aimed to test whether changes in continuous cardiac index (CCI), PPV, and stroke volume variation (SVV) after a mini-fluid challenge (100 ml of fluid during 1 min) could predict fluid responsiveness in these patients. Methods We prospectively studied 49 critically ill, deeply sedated, and mechanically ventilated patients (tidal volume −1 of ideal body weight) without cardiac arrhythmias, in whom a fluid challenge was indicated because of circulatory failure. The CCI, SVV (PiCCO™; Pulsion), and PPV (MP70™; Philips) were measured before and after 100 ml of colloid infusion during 1 min, and then after the additional infusion of 400 ml during 14 min. Responders were defined as subjects with a ≥15% increase in cardiac index (transpulmonary thermodilution) after the full (500 ml) fluid challenge. Areas under the receiver operating characteristic curves (AUCs) and the grey zones were determined for changes in CCI (ΔCCI 100 ), SVV (ΔSVV 100 ), and PPV (ΔPPV 100 ) after 100 ml fluid challenge. Results Twenty-two subjects were responders. The ΔCCI 100 predicted fluid responsiveness with an AUC of 0.78. The grey zone was large and included 67% of subjects. The ΔSVV 100 and ΔPPV 100 predicted fluid responsiveness with AUCs of 0.91 and 0.92, respectively. Grey zones were small, including ≤12% of subjects for both indices. Conclusions The ΔSVV 100 and ΔPPV 100 predict fluid responsiveness accurately and better than ΔCCI 100 (PiCCO™; Pulsion) in patients with circulatory failure and ventilated with low volumes.