Cerebral hyperaemia after isoflurane anaesthesia for craniotomy of patients with supratentorial brain tumour

Assessment of cerebral blood flow velocities, brain midline shift and optic nerve sheath diameter by ultrasound in patients undergoing elective craniotomy: A prospective observational feasibility study

BACKGROUND

Brain ultrasound allows measuring the cerebral flow velocity, brain midline shift and optic nerve sheath diameter. Literature is scarce in determining the feasibility to perioperatively perform these measurements altogether and the cerebrovascular behavior in patients scheduled for elective craniotomy.

METHODS

We assessed bilateral cerebral flow velocities, composite index, brain midline shift and optic nerve sheath diameter by cerebral ultrasound in patients scheduled for elective craniotomy before anesthetic induction, at extubation, and at 6 and 24 h after. The aim was to assess the feasibility of brain ultrasound in patients for elective craniotomy and to describe the changes in cerebral flow velocities, brain midline shift and optic nerve sheath diameter from baseline values at different times in the postoperative period.

RESULTS

Sixteen patients were included, of these two were excluded from analysis due to an inadequate sonographic window. There were no changes throughout the study regarding cerebral flow velocity, brain midline shift nor optic nerve sheath diameter assessments. All parameters were maintained in the physiological range without significant variations during the procedure. No perioperative complications were detected.

CONCLUSIONS

The results of our study show the feasibility to perform a perioperative assessment of cerebral flow velocity, brain midline shift or optic nerve sheath diameter jointly and successfully to obtain additional information of baseline cerebral hemodynamics in patients scheduled for elective craniotomy and their postoperative changes during the first 24 h. Future studies with lager samples are needed to address the efficacy of cerebral ultrasound as a monitoring tool.

Cerebral blood flow is decoupled from blood pressure and linked to EEG bursting after resuscitation from cardiac arrest

In the present study, we have developed a multi-modal instrument that combines laser speckle imaging, arterial blood pressure, and electroencephalography (EEG) to quantitatively assess cerebral blood flow (CBF), mean arterial pressure (MAP), and brain electrophysiology before, during, and after asphyxial cardiac arrest (CA) and resuscitation. Using the acquired data, we quantified the time and magnitude of the CBF hyperemic peak and stabilized hypoperfusion after resuscitation. Furthermore, we assessed the correlation between CBF and MAP before and after stabilized hypoperfusion. Finally, we examined when brain electrical activity resumes after resuscitation from CA with relation to CBF and MAP, and developed an empirical predictive model to predict when brain electrical activity resumes after resuscitation from CA. Our results show that: 1) more severe CA results in longer time to stabilized cerebral hypoperfusion; 2) CBF and MAP are coupled before stabilized hypoperfusion and uncoupled after stabilized hypoperfusion; 3) EEG activity (bursting) resumes after the CBF hyperemic phase and before stabilized hypoperfusion; 4) CBF predicts when EEG activity resumes for 5-min asphyxial CA, but is a poor predictor for 7-min asphyxial CA. Together, these novel findings highlight the importance of using multi-modal approaches to investigate CA recovery to better understand physiological processes and ultimately improve neurological outcome.