Evaluation of the EEG Connectivity Using Predominantly Dexmedetomidine Anesthesia Versus Traditional TCI Propofol in Fragile Brains

Elderly brains that present a lower intrinsic cortical activity are very dependent on arousal feeding. In these patients, a strong blockade of afferences generates a synchronic state with a high tendency to sleep. This is done with drugs such as Dexmedetomidine and its indirect effect of inhibiting the amplification of signals and opioids such as remifentanil. Then, by adding a micro-dose of a gabaergic substance to induce loss of consciousness, unconsciousness would be maintained due to the low requirement of a fragile and synchronous brain by a slow continuous injection of an alpha2 agonist. In previous experience, doses of about one-fifth of the usual would be sufficient to maintain unconsciousness (or perhaps disconnected consciousness that could be useful in avoiding excessive depression in slowed integration pathways). These patients also present deficits in the orexinergic response that manifest themselves in greater neuronal inertia and delayed awakening. Gabaergic drugs (propofol and sevoflurane) are especially depressing to orexinergic nuclei.

This approach to the elderly brain could have an impact on recovering more easily connectivity of those CNC networks.

In elderly patients, one aspect that could control the phenomena of altered connectivity and its impact in developing delirium is the limitation of connection with the environment before the capacity of integration of cortical information has been completely recovered. To analyze frontoparietal connectivity, front frontal coherence, phase lag index, or similar it is necessary to a multichannel EEG (e.g. 10 channels). Otherwise, the frontal EEG from the SEDline monitor device allowed to analyze only spectral characteristics (power, peak frequency, etc.) and correlate them with clinical observations (MoCA).