13 patients subjected to the operational treatment of intracranial aneurysm with isoflurane anaesthesia manifested haemodynamic changes in systemic and cerebral circulation. The evaluation was based upon selected parameters monitored during the operation including expiratory terminal carbon dioxide concentration (ETCO2), core temperature, mean arterial blood pressure (MABP) and cerebral arterio-venous oxygen content difference (AVDO2) - paying special attention to these parameters during the following stages of operation: I - 5 minutes before skin incision, II - 5 minutes after skin incision, III - 5 minutes after meningotomy, IV - 5 minutes after clipping the aneurysm, V - 5 minutes after meningorrhaphy. In the subsequent stages of operation, MABP mean values fluctuated statistically significantly, and there was a negative linear correlation with statistically significant changes of mean AVDO2 values (r=-9107, p<0.05). On the basis of the analysis of mean PaCO2,ETCO2,PjCO2, and core temperature it may be claimed that there is no significant influence of these parameters upon cerebral blood flow and oxygen consumption by cerebral tissue. The results obtained in the present study allow for the conclusion that general complex anaesthesia with low isoflurane concentration does not ensure a full stabilisation of both systemic and cerebral circulation in the most important stages of the operation of intracranial aneurysm. It may also be claimed that the correlation of MABP with AVDO2, changes may indicate the deficiency of the autoregulation mechanism of cerebral circulation in the course of subarachnoid bleeding following the rupture of intracranial aneurysm.

Keywords: cerebral arterio-venous oxygen content, Isoflurane, neuroanaesthesia