A computer-based method for continuous single pulse analysis of intracranial pressure waves.

Abstract

The single pulse analysis of intracranial pressure waves provides valuable information about the autoregulative processes after head injury. This method has not been used for routine clinical assessment as yet. Current methods for evaluation of intracranial pressure waves are based on spectral analysis or related techniques. This imposes restrictions on the wave sequences available for the investigation of ICP attributes. Therefore, we have developed a computer-based method, which enables continuous analysis of each pulse of the ICP wave, in any clinical setting. Firstly, the raw data of the ICP wave is continuously recorded by the Multifunctional Anaesthetic Record System (MARS, Hewlett Packard). The recorded data is then subjected to single pulse wave analysis by our software. Each single pulse is identified by the algorithm. The maximum, minimum and mean value, as well as amplitude and gradient are calculated in each pulse pressure. All conceivable correlations of the listed parameters can be examined. We applied our software in 9 cases with head injury and evaluated the measurements over 59 days (1400 h). More than 7 million single pulse pressures have been analyzed off-line. The software proved to be accurate and easy to apply. It was possible to calculate correlations between the different wave attributes on a broad basis of data. Parameters of special clinical interest were the amplitude of the single pulse pressure and the gradient. This method is an improvement on ICP single pulse pressure analysis and facilitates its clinical application. It creates the possibility for continuous long-term analysis of the ICP wave attributes under any clinical condition without loss of data. There are indications that the amplitude and the gradient of the ICP pulse pressure could provide valuable additional information for clinical assessment. However, further evaluation is required.