Transcranial Doppler ultrasonography in neurosurgery: Effects of intracranial tumour on right middle cerebral artery flow velocity during induction of anaesthesia

The right middle cerebral artery flow velocity (MCAFV) was measured by transcranial Doppler ultrasonography in neurosurgical patients with and without intracranial tumours during anaesthetic induction and endotracheal intubation. With institutional and patient consent, 20 non-tumour and 85 tumour-bearing neurosurgical patients were enlisted. The right middle cerebral artery was insonated with a pulsed-wave range-gated transcranial Doppler at 2 MHz, and MCAFV was recorded via a video graphics printer. The mean MCAFV, pulsatility index, use of anaesthetic drugs, heart rate, mean arterial pressure, and end-tidal CO₂ were recorded on preinduction, postinduction, intubation, and 90 to 180 s postintubation. There was no demographic, systemic haemodynamic, or anaesthetic difference between groups except for a predominance of women in the tumour group. In all patients, mean arterial pressure and MCAFV demonstrated with time a significant decrease with anaesthetic induction, increase with endotracheal intubation, and decrease post intubation. The right MCAFV was significantly higher in both tumour and right-sided tumour patients compared to non-tumour patients. There was no difference in left-sided tumour patients compared to non-tumour patients. These data indicate that intracranial tumours have cerebrovascular effects, causing either hyperaemia or vasoconstriction, and that the effects of anaesthetic induction and intubation agree with previously reported effects on cerebral blood flow and intracranial pressure.