Certain kind of neurosurgical procedures require intraoperative alertness of the patient, for example to perform speech tests during brain tumor resection. With respect to anaesthesia, it is therefore required that the patient is asleep during the beginning and the end of the procedure, however fully awake in between. To do so, the anaesthetic propofol is used and an accurate knowledge of its pharmacokinetic and -dynamic (pk/pd) parameters is required to optimally control anaesthesia. However, diverse pk/pd-parameter sets have been described in the literature.

The aim of the study is to investigate whether the pk/pd model proposed by Marsh et al. or by Schnider et al. more accurately describe the pk/pd of propofol during awake craniotomy.

Inclusion Criteria:

• patients scheduled for awake craniotomy

Exclusion Criteria:

• pregnancy

Patients of a University Hospital requiring an awake craniotomy for resection of a brain tumor or lesion