The influence of propofol on middle cerebral artery flow velocity (VMCA) in patients with unruptured intracranial aneurysms during induction of general anaesthesia

Background: The estimated prevalence of unruptured intracranial aneurysms is 3%. Standard monitoring does not enable one to assess the influence of anaesthetics on the factors determining intracranial homeostasis. Thanks to transcranial Doppler ultrasonography, middle cerebral artery flow velocity (VMCA), reflecting cerebral blood flow, can be measured. The aim of the study was to assess the effects of propofol on intracranial homeostasis in patients with unruptured intracranial aneurysms during the induction of anaesthesia based on VMCA changes. Methods: The study encompassed 21 patients (group II) anaesthetised for elective craniotomy due to unruptured intracranial aneurysms. The control group (group I) included 21 patients who underwent discoidectomy. VMCA, as well as HR, MAP, etCO₂, and SpO₂ were monitored at the following time points: T0 — onset of study; T1 — after 1 minute; T2 — onset of preoxygenation; T3 — after 1 minute of preoxygenation; T4 — administration of fentanyl; T5 — 1 minute after fentanyl; T6 — administration of propofol; T7 — 1 minute after propofol; T8 — intubation; T9 — 1 minute after intubation; T10 — 2 minutes after intubation. Results: In both groups, no changes in mean HR, etCO₂ and SpO₂ were observed at the successive time points of observation. In groups I and II, an MAP decrease between T6 and T7 and an MAP increase between T7 and T9 were noted. There were no intergroup differences in mean values of MAP at the times of observation. In both groups and bilaterally, a VMCA decrease was recorded between T6 and T7 and an increase between T7 and T8. There were no intergroup differences in mean values of VMCA at the times of observation. In both groups, a weak correlation between VMCA and MAP changes was found bilaterally. Conclusions: Propofol depresses the cerebral circulation during the induction of anaesthesia. The presence of an unruptured aneurysm does not affect the reactivity of the cerebral vessels during the induction of anaesthesia with propofol.

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