Messina A, et al. - In this prospective bi-centric interventional study conducted in two general intensive care units (ICUs), researchers tested the performance of a novel test, based on the application of a ventilator-generated sigh, to predict fluid responsiveness in 40 ICU patients undergoing pressure support ventilation (PSV). They randomly applied 4-s sighs at three different inspiratory pressures and thereafter evaluated the variations in arterial systolic pressure (SAP), pulse pressure (PP) and stroke volume index (SVI). They obtained hemodynamic measurements by directing a radial arterial signal to the MOSTCARE pulse contour hemodynamic monitoring system. For volume expansion (VE), 500 mL of crystalloids was administered over 10 min. If a VE-induced increase in cardiac index (CI) ≥ 15% was observed, a patient was considered a responder. Compared with area under the receiver operating characteristic (ROC) curve (AUC) for PP (0.91) and SVI (0.83), a significantly greater AUC was generated for the slope of SAP (0.99; sensitivity 100.0% (79.4–100.0%) and specificity 95.8% (78.8–99.9%). Among those included in the logistic regression, the slope for SAP was the only parameter found to be independently associated with fluid responsiveness. Overall, fluid responsiveness in a selected ICU population undergoing PSV was reliably predicted by analysis of the slope for SAP after the application of three successive sighs and the nadir of PP after Sigh₃₅.