Reciprocal influence of slow waves extracted in intracranial pressure, arterial pressure and cerebral blood velocity signals

Slow waves in intracranial pressure (ICP) and related signals seems of interest to evaluate the dynamic autoregulation, i.e. by comparison of the frequency links between an intracranial signal, e.g. ICP, cerebral blood velocity (CBV), and arterial blood pressure (ABP). To clarify the links, we compared two frequency methods based on coherence function to estimate the influence of ICP, ABP and CBV on couples, respectively CBV-ABP, ICP-CBV and ICP-ABP, of slow waves in the B and the UB bands. We found that B and UB waves activity in ICP, CBV and ABP had reciprocal influences, except for the UB activity in ICP-CBV link which seems to be less sensitive to ABP. These data confirmed the interest of to analyse the slow wave activity to evaluate dynamic autoregulation. The interest of taking into account the reciprocal influence of the signals must be evaluated.