| In the neurointensive care unit (NICU) there is a need for a single bedside monitor for continuously monitoring the function of the patient's central nervous system. This dissertation describes the development of a system of hardware and software for continuously and automatically monitoring the ongoing neurological condition of patients in the NICU. The system samples several electrophysiological waveforms at regular intervals along with routinely monitored physiological parameters. The electrophysiological data consists of brainstem auditory, somatosensory and visual evoked potentials and epochs of the electroencephalogram (EEG). The system applies peak detection and spectral analysis to extract salient parameters from the raw waveforms. These parameters are assembled into a state vector representing the patient's neurophysiological state. The parameters include the latencies and amplitudes of the significant peaks in the brainstem auditory, somatosensory and visual evoked potentials, the spectral pole positions, peak frequencies and energy distributions of the EEG and such physiological parameters as heart rate, blood pressure and intracranial pressure. A display summarizing the history of the patient's state is provided for visual review. The results are also made available on the network for review and further analysis on the local network. A web-based interface makes review possible anywhere within the hospital's secure intranet during and after monitoring. Experimental data from six intensive care patients show that certain regions of the state space correspond with particular pathologies and this may have diagnostic value in particular patients. Experimental data from angioplasty and stent patients suggest that the electrophysiological changes correspond with the induced physiological changes in the central nervous system as they occur in real time. If these results are extrapolated to NICU patients, it implies that further analysis of the state space dynamics may be of prognostic value in these patients. In particular, the results suggest that continuous multimodality electrophysiological monitoring of this type may potentially contribute to the quality of care of stroke patients with hemorrhagic and edematous brain injuries during the critical period during which tissue shifts and possible herniation may give rise to pressure on the brainstem and other structures, with associated morbidity or mortality. |
