CardioQ vs Thermodilution Measurements of Cardiac Output

Twenty-five patients are planned enrolled. After induction of anesthesia, insertion of the PAC and the CardioQ probe, the patient are placed in the following successive positions: a) supine, b) head-down tilt, c) head-up tilt, d) supine, e) supine with phenylephrine administration f) pace heart rate 80 bpm, g) pace heart rate 110 bpm. CO are measured simultaneously using the TEE and thermodilution technique.