INTRODUCTION: Patients undergoing lung resection are vulnerable to fluid overhydration. Recently, goal-directed fluid therapy using transoesophageal Doppler monitoring (TDM) has been shown to improve postoperative clinical outcome. The aim of this study was to assess the feasibility of TDM during open-chest procedures for guiding fluid and hemodynamic treatment. METHODS: We performed an observational prospective study including 127 high-risk patients undergoing lung cancer resection. A restrictive fluid strategy was targeted to achieve a stroke volume index (SVI) > or = 30 ml/min/m(2). Besides standard hemodynamic measurements, stroke volume index (SVI), corrected flow time (FTc), maximal acceleration (MA) and velocity (PV) were recorded during two-lung ventilation (TLV) and one-lung ventilation (OLV). RESULTS: Doppler flow tracings could not be obtained in 4 patients during TLV (3.1%) and in 6 patients during OLV (4.9%). Preoperatively, 96 pts had SVI > or = 30 ml/min/m(2) (N-SVI group) whereas 21 patients had SVI < 30 ml/min/m(2) (L-SVI group) associated with lower FTc values. After OLV, SVI transiently decreased (-17 +/- 9%; P < 0.05) in the N-SVI group whereas in the L-SVI group, SVI increased steadily until the end of surgery (+40 +/- 12%). Other flow-related parameters as well as heart rate and mean arterial pressure remained unchanged. Surgical and medical characteristics did not differ between the two groups, except that larger volumes of colloids were administered intraoperatively in the L-SVI group (+2.2 +/- 0.6 ml/min/h compared with N-SVI group, P < 0.05). CONCLUSION: In thoracic surgical patients, TDM can be used to detect and correct low flow conditions and to guide hemodynamic support during the intraoperative period.