Subdural pressure and brain condition during propofol vs isoflurane - nitrous oxide anaesthesia in patients undergoing elective supratentorial tumour surgery.

Total intravenous anaesthesia has received much importance than inhalational anaesthesia in neuroanaesthetic practice. In an effort to determine whether any important clinical differences occur, studies concerning intracranial pressure (ICP), degree of dural tension and degree of brain swelling during intravenous and inhalational based anaesthesia are warranted like the present one. A total of 68 patients were assigned randomly to one of two groups. In Group-I(n=34), anaesthesia was induced with propofol (1-3mg.kg(-1)) and maintained with propofol (6-10mg.kg(-1).hr(-1)) and fentanyl (2-3mcg.kg(-1).hr(-1)). In Group-II (n=34), anaesthesia was induced with propofol (1-3mg.kg(-1)) but maintained with isoflurane, nitrous oxide and fentanyl (2-3mcg.kg(-1).hr(-1)). Moderate hypocapnia was applied to maintain arterial carbon dioxide around 30mmHg. Mean arterial blood pressure was stabilized with phenylephrine whenever necessary. Subdural intracranial pressure, mean arterial pressure, cerebral perfusion pressure were monitored before and after 10min period of hyperventilation. Furthermore, the tension of dura before and after of hyperventilation and the degree of brain swelling after opening of dura were also estimated by the neurosurgeon. No differences were found between the groups with regards to demographics, neuroradiologic diagnosis, position of head and time of ICP measurement. Before hyperventilation, both ICP and dural tension were significantly lower in Group I compared with Group-II (P<0.05). But after hyperventilation there was no significant difference of ICP and dural tension in between groups. The degree of brain swelling after opening of dura was similar in both groups. There was a positive correlation between measured ICP and brain swelling score.