In order to prevent [[cerebral vasospasm]] after a [[subarachnoid hemorrhage]] (SAH), the so-called [[triple H therapy]] ([[hypertension]], [[hypervolemia]], [[hemodilution]]) could be applied. In these cases, colloidal solutions containing [[Hydroxyethyl starch]] (HES) are used to induce [[hypervolemia]]. The administration of HES is very much under debate for the mentioned use because in general the application of HES for the treatment of critically ill patients has been reduced tremendously in the last years due to its [[nephrotoxic]] effects. In this context, there are limited data investigating the influence of HES on the [[blood-brain barrier]].