Evaluation of the Pressure Measurement Function of an Implantable Multimodality Probe

To monitor changes in brain pathology, it is important to quantify multiple indices simultaneously. However, installing several probes at a measurement site enhances the risk of bleeding and infection. To solve this problem, a flexible multimodal, multichannel probe that can measure electrocorticographic signals, hemodynamics, and surficial temperatures of the cerebral cortex was previously developed. In this study, an intracranial pressure sensor was mounted on this probe to monitor increased intracranial pressure, which is a life-threatening condition caused by brain injury or other pathologies. As a result of animal experiments performed on two cats, the measurement accuracy and drift waveform were found to differ depending on the shape of the reinforcing plate. The result showed that plate A demonstrated a good correlation coefficient with the reference, while sufficient measurement accuracy was not achieved for the case of plate B. However, the correlation coefficient and limit of agreement were improved via filtering of the probe values. On the basis of these results, it can be considered that the probe captured changes in pressure, such as those due to respiration and pulse. However, its accuracy was reduced owing to the influences of the drift.