Can we use pulse pressure variations to predict fluid responsiveness in patients with ARDS?

Excerpt

Respiratory variations in stroke volume have been shown to be associated with preload dependency in mechanically ventilated patients without spontaneous breathing movements. Pulse pressure variations (ΔPP), a surrogate of stroke volume variation (SVV), predict fluid responsiveness better than static indices of cardiac preload [1, 2]. However, SVVs and ΔPP are caused by respiratory-induced changes in preload that may be limited when patients are ventilated at low tidal volume. The reliability of ΔPP could hence be theoretically limited in mechanically ventilated patients with low tidal volume [3]. An experimental study showed that changes in SVV between hemorrhage and fluid loading were limited when tidal volume was 5 ml/kg in contrast with larger changes at 10 and 15 ml/kg [4]. In mechanically ventilated acute respiratory distress syndrome (ARDS) patients, De Backer et al. [5] reported that the predictive value of ΔPP for fluid responsiveness decreased when a tidal volume lower than 8 ml/kg was applied [area under the ROC (AUC ROC) = 0.71 ± 0.09]. A similar AUC ROC (0.768) was recently reported in 22 ARDS patients ventilated with tidal volume ranging from 5.3 to 8.3 ml/kg [6]. …