The optimal amount and type of fluid given during surgery has not been defined. It has been agreed that hypovolemia must be avoided, but at the same time it has been agreed that fluid excess is harmful for organ function.When distributing fluids it is usually either crystalloids og colloids which are given. The effects of the two types of fluid have not been compared. Our hypothesis is that using a colloid (HES 130/0,4) will improve orthostatic function, nausea/vomiting and shorten hospital stay, compared to using a crystalloid (Lactated Ringer's solution).The amount of fluid the patient receives, will be individually tailored by monitoring SV using esophageal Doppler technique during surgery.