A Fiberoptic Device Suitable for Subdural Pressure Measurement

The benefit of ICP management has been clearly established in patients with severe brain injury. Elevated ICP above 20 mmHg should be avoided as it has been demonstrated that time above this critical level is correlated with poor outcome [1]. Although the monitoring of intracranial pressure by direct ventricular catheterization as introduced by Janny and Lundberg remains the gold standard, the recent introduction of fibre optic devices (FOD) for measurement of ICP has added a new dimension to ICP monitoring [2, 3]. Parenchymal recordings of ICP are now considered routine in many centers. However, the use of an FOD device in the subdural space and the relationship of subdural FOD pressure to tissue FOD and ventricular fluid pressure (VFP) pressure remains to be clarified. The objective of this study was to evaluate the capability of a highly flexible FOD device (Innerspace Inc. Irvine CA. USA) for measurement of subdural and tissue pressure in cats. A second objective was to determine the ability of parenchymal FOD’s to reflect tissue pressure gradients in response to expansion of an epidural balloon and to determine whether these gradients are sustained.