After intubation under general anesthesia, radial arterial is cannulated and pressure transducer is connected to MostCare(core technique PRAM). CI, SVRI, SVI, SVV, dp/dt and HR are recorded before and after a infusion of dopamine or norepinephrine to elevate 10% of mean arterial pressure. Changes of these hemodynamic data are compared.
Participants under general anesthesia will be randomly treated with an adjusted dose dopamine or norepinephrine to elevate 10% of mean arterial pressure. Systemic hemodynamic data is recorded by PRAM and the change of cardiac index is compared between groups.