The stroke volume variation (SVV), measured using the Vigileo-FloTrac system (Edwards Lifescience, Irvine, CA), has been shown to able to predict fluid responsiveness during one-lung ventilation (OLV) in patients undergoing pulmonary lobectomy (sensitivity: 82.4%, specificity: 92.3%).1 Many parameters such as tidal volume (TV),1-2 positive end-expiratory pressure (PEEP),3 respiratory rate (RR), 4 chest and lung compliance,5 heart rate and rhythm, and ventricular function and afterload,6-7 all have been documented to have effects on the SVV.