Intracranial hypertension in intensive care
Keywords:Transcranial Doppler, intracranial pressure, cerebral oxygenation, multimodal monitoring, traumatic brain injury
Description of this clinical case - a patient suffering from a severe head trauma followed by acute intracranial hypertension - allows us to approach advantages and limitations of various possibilities of neurological monitoring.
From the first minutes, control of systolic and mean arterial pressure (MAP) is the essential prerequisite. Hypotension is prohibited. End-tidal CO2 reflects arterial PCO2 (aPCO2), essential element in the control of cerebral hemodynamic. Transcranial Doppler allows the immediate assessment of cerebral blood flow on the two middle cerebral arteries. Low cerebral blood flow is easy to diagnose, its correction is urgent (increase MAP and/or osmotherapy). Normal flow is reassuring. Poorly estimated by the CTscan, measuring intracranial pressure (ICP) makes possible the evaluation of cerebral perfusion pressure (CPP=MAP-ICP) and allows us to vary the MAP level to control ICP and/or CPP. The difficulty in controlling CPP leads to specifying cerebral oxygenation, either locally (PtiO2) or globally (SvjO2). Temperature control, and its links with aPCO2, is a strong element in the control of the intracranial hypertension.
Each technique is defined by some objectives but also makes it possible to palliate the limits of other technique, thus defining interest of multimodal monitoring. Understanding relationships between MAP, ICP, PtiO2, aPCO2 and temperature allows these elements to be for the best fitted to find the therapeutic balance that allows to overcome cerebral oedema and limits ischemia. This very assiduous control will be relaxed as soon as possible with precaution to allow the patient to gain in autonomy, to judge sequelae and to start the rehabilitation work.
Keywords: Transcranial Doppler, intracranial pressure, cerebral oxygenation, multimodal monitoring, traumatic brain injury.