The data of systolic pressure and ScO2 wil be recorded at 5-6 second intervals on the device's accessory disk drive for later analysis. To establish a baseline for blood pressure and ScO2. No prehydration will be given. Lactated Ringers' solution at 0.4 ml kg-1 min-1 will be infused after anesthesia. Supplemental oxygen is planned to be administered in case SpO2 values would be below 91%.