Cerebrospinal fluid and blood propofol concentration during total intravenous anaesthesia for neurosurgery

Background. The aim of this paper is to compare the propofol concentration in blood and cerebrospinal fluid (CSF) in patients scheduled for different neurosurgical procedures and anaesthetized using propofol as part of a total intravenous anaesthesia technique. Methods. Thirty-nine patients (ASA I-III) scheduled for elective intracranial procedures, were studied. Propofol was infused initially at 12 mg kg(-1) h(-1) and then reduced in steps to 9 and 6 mg kg(-1) h(-1). During anaesthesia, bolus doses of fentanyl and cis-atracurium were administered as necessary. After tracheal intubation the lungs were ventilated to achieve normocapnia with an oxygen-air mixture (Fi(O2)=0.33). Arterial blood and CSF samples for propofol examination were obtained simultaneously directly after intracranial drainage insertion and measured using high-performance liquid chromatography. The patients were divided into two groups depending on the type of neurosurgery. The Aneurysm group consisted of 13 patients who were surgically treated for ruptured intracranial aneurysm. The Tumour group was composed of 26 patients who were undergoing elective posterior fossa extra-axial tumour removal. Results. Blood propofol concentrations in both groups did not differ significantly (P>0.05). The propofol concentration in CSF was 86.62 (sd 37.99) ng ml(-1) in the Aneurysm group and 50.81 (26.10) ng ml(-1) in the Tumour group (P<0.005). Conclusions. Intracranial pathology may influence CSF propofol concentration. However, the observed discrepancies may also result from quantitative differences in CSF composition and from restricted diffusion of the drug in the CSF.