Anesthetic Guidance of Depth of Anesthesia and Indirect Cardiac Output Monitoring in Thoracic Surgery

In the M-Entropy group, dosage of volatile anesthetics will be adjusted to achieve the response and state entropy values between 40 and 60 from the start of anesthesia to the end of surgery. In the control group, dosage of volatile anesthetics will be titrated according to clinical judgment.

If stroke volume variation is ≥ 10%, a bolus of 150 ml of crystalloid fluid will be given until the stroke volume variation is \< 10%. If mean arterial pressure is \< 70 mmHg and/or cardiac index \< 2.5 l·min-1·m-2 despite the stroke volume variation of \< 10% following fluid challenge, single or consecutive boluses of ephedrine 4 mg and/or continuous intravenous infusion of norepinephrine 2-10 μg·min-1 will be administered.