Pulse pressure variation as a predictor of fluid responsiveness during one-lung ventilation for lung surgery using thoracotomy: Randomised controlled study

Background and objective Pulse pressure variation (PPV) is increasingly advocated as a predictor of fluid responsiveness in patients receiving mechanical ventilation. However, the ability of PPV has never been studied during one-lung ventilation (OLV). Therefore, we evaluated the value of PPV to predict fluid responsiveness in patients receiving conventional and protective OLV using receiver operating characteristic (ROC) analysis, respectively. Methods Forty-nine patients undergoing lung surgery requiring OLV were enrolled in this study. Patients were randomised either to group P [patients receiving protective OLV with tidal volume 6 ml kg^-1, inspired oxygen fraction (F₁O₂) of 0.5 and positive end-expiratory pressure (PEEP) of 5cmH₂O) or group C (patients receiving conventional OLV with tidal volume of 10 ml kg^-1,F₁O₂ of 1.0 and no PEEP). Following OLV, PPV and cardiac output were measured before and 12 min after fluid loading (7 ml kg^-1 hydroxyethyl starch 6%). Patients whose cardiac indices increased by at least 15% to fluid loading were defined as the responders. Results The areas under ROC curve for PPV were 0.857 (P=0.006) in group P and 0.524 (P=0.839) in group C, respectively. The optimal threshold value given by ROC analysis for PPV was 5.8% in group P. Conclusions PPV could predict fluid responsiveness only during protective OLV, but not conventional OLV. PPV would be helpful for fluid management in patients receiving protective OLV for lung surgery using thoracotomy.