Cerebral Perfusion Variation During Blood Pressure Changes in ICU: Relationship Between Transcranial Doppler, Frontal EEG and Cerebral Oximetry: a Prospective Observational Study

The risk associated with arterial hypotension during anesthesia for intensive care sedation has been demonstrated, but the threshold at which consequences for perfusion of one or more organs appear varies according to the mechanism of hypotension, associated abnormalities (HR, cardiac output and oxygen transport) and the patient's terrain.

Currently, a mean arterial pressure greater than 60 mm Hg (1) and a reduction of less than 30-50% from the value measured before sedation are commonly used to ensure good perfusion of all organs. In intensive care, it is recommended to maintain a MAP between 60 and 70 mmHg and a Cerebral Perfusion Pressure (CPP) > 50 mmHg for neurocompromised patients with Intra Cranial pressure (ICP) measure. Normally, cerebral blood flow is self-regulated, allowing adaptation of cerebral blood flow to oxygen requirements at different levels of high and low blood pressure. However, this protective mechanism may fail for a degree of hypotension that depends on several factors such as the age or vascular status of the patient.

The aim of the study is to measure non-invasively, easily and reliably the variations of cerebral perfusion in patients with or without cardiovascular risk factors during controlled variations performed during routine care to set the blood pressure level within the recommended safety standards during sedation in intensive care unit. Cerebral perfusion and cerebral O2 adequacy will be compared and assessed by continuous and simultaneous measurements of cerebral blood flow by transcranial Doppler (CTD), cerebral O2 adequacy by near-infrared spectroscopy (NIRS) and a parameter of cerebral function by electroencephalogram (EEG) - frontal EEG.

The objective for a given patient is to detect a possible threshold pressure value that could impact blood flow velocity (Doppler) and possibly EEG and cerebral oximetry.

This clinical research is carried out on adult patients hospitalized in intensive care. Their non-opposition to participate in this study will be collected during the hospitalization or, if necessary, the trusted person/relative of a patient unable to express his/her will. The protocol starts after at least 12 hours of stablisation in the intensive care unit.