Zanatta, Paolo and Toffolo, Gianna Maria and Sartori, Elisa and Bet, Anna and Baldanzi, Fabrizio and Agarwal, Nivedita and Golanov, Eugene (2012) The human brain pacemaker: synchronized infra-slow neurovascular coupling in patients undergoing non-pulsatile cardiopulmonary bypass. [Preprint]
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In non-pulsatile cardiopulmonary bypass surgery, middle cerebral artery blood flow velocity (BFV) is characterized by infra-slow oscillations of approximately 0.06 Hz, which are paralleled by changes in total EEG power (EEG-PV), measured in 2 s intervals. Since the origin of these BFV oscillations is not known, we explored their possible causative relationships with oscillations in EEG-PV at around 0.06 Hz. We monitored 28 patients undergoing non-pulsatile cardiopulmonary bypass using transcranial Doppler sonography and scalp electroencephalography at two levels of anaesthesia – deep (prevalence of burst suppression rhythm) and moderate (prevalence of theta rhythm).
Under deep anaesthesia, the EEG bursts suppression pattern was highly correlative with BFV oscillations. Hence, a detailed quantitative picture of the coupling between electrical brain activity and BFV was derived, both in deep and moderate anaesthesia, via linear and non linear processing of EEG-PV and BFV signals, resorting to widely used measures of signal coupling such as frequency of oscillations, coherence, Granger causality and cross-approximate entropy. Results strongly suggest the existence of coupling between EEG-PV and BFV. In moderate anaesthesia EEG-PV mean dominant frequency is similar to frequency of BFV oscillations (0.065 ± 0.010 Hz vs 0.045 ± 0.019 Hz); coherence between the two signals was significant in about 55% of subjects, and the Granger causality suggested an EEG-PVBFV causal effect direction. The strength of the coupling increased with deepening anaesthesia, as EEG-PV oscillations mean dominant frequency virtually coincided with the BFV peak frequency (0.062 ± 0.017 Hz vs 0.060 ± 0.024 Hz), and coherence became significant in a larger number (65%) of subjects. Cross-approximate entropy decreased significantly from moderate to deep anaesthesia, indicating a higher level of synchrony between the two signals.
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|Anno di Pubblicazione:||07 December 2012|
|Key Words:||infra-slow oscillations, non-pulsatile cardiopulmonary bypass, multimodality neuromonitoring, brain blood flow velocity, EEG power|
|Depositato il:||11 Dec 2012 12:47|
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