1. st cardiac output measurement (horizontal supine position): Transesophageal echocardiographic cardiac output measurements, data recorded and in the meantime the data of the FloTrac system (© Edwards Lifesciences) monitor recorded also.
2. nd cardiac output measurement (Trendelenburg position): The operating table was then tilted in - 30 ° Trendelenburg (head-down) position. Echocardiographic measurements and FloTrac system (© Edwards Lifesciences) data were recorded.
3. rd cardiac output measurement: The patients were positioned from Trendelenburg to reverse-Trendelenburg, the above-described data were recorded again.

1. st cardiac output measurement (horizontal supine position): Transesophageal echocardiographic cardiac output measurements, data recorded and in the meantime the data of the FloTrac system (© Edwards Lifesciences) monitor recorded also.
2. nd cardiac output measurement (reverse Trendelenburg position): The operating table was then tilted in + 30 ° reverse Trendelenburg (head-up) position. Echocardiographic measurements and FloTrac system (© Edwards Lifesciences) data were recorded.
3. rd cardiac output measurement: The patients were positioned from reverse Trendelenburg to Trendelenburg, the above-described data were recorded again.

Concomitant cardiac output measurement with transesophageal echocardiography and with the FloTrac/Vigileo system (© Edwards Lifesciences) (Edwards Lifesciences, Irvine, CA) device in 3 different positions (horizontal supine, Trendelenburg and reverse Trendelenburg position).

To study the fourth generation FloTrac/Vigileo system accuracy to estimate cardiac output (L/min) in horizontal supine position in anesthetized patients undergoing elective major abdominal surgery. The reference method of cardiac output (L/min) measurement used was the transesophageal echocardiography. The two cardiac output measurement techniques were assessed using Bland-Altman method.

To study the fourth generation FloTrac/Vigileo system accuracy to estimate cardiac output (L/min) in Trendelenburg position in anesthetized patients undergoing elective major abdominal surgery. The reference method of cardiac output (L/min) measurement used was the transesophageal echocardiography. The two cardiac output measurement techniques were assessed using Bland-Altman method.

To study the fourth generation FloTrac/Vigileo system accuracy to estimate cardiac output (L/min) in reverse Trendelenburg position in anesthetized patients undergoing elective major abdominal surgery. The reference method of cardiac output (L/min) measurement used was the transesophageal echocardiography. The two cardiac output measurement techniques were assessed using Bland-Altman method.