Evaluation of ICP by computerized bedside monitoring: methods and clinical significance

The recording of intracranial pressure (ICP) is increasingly performed routinely in the hospital setting. Documentation of the pressure course over long time intervals has been performed, until recently, with paper tracings. Objective means of evaluation are lacking, however, for the quantification of pressure-dynamics. We have therefore tested several different statistical and graphical methods of evaluation to improve the efficacy of ICP monitoring. Calculations were done on epidural and transfontanel pressure monitoring. Analyses were performed both on-line and off-line. Graphical methods used included time-plot graphs, histograms, correlations analysis and pulse-amplitude/mean pressure diagrams (PA/Pm); statistical values calculated included mean, variance, standard deviation, coefficient of skewness, coefficient of kurtosis, coefficient of variation and the range. Data obtained from patients with normal intracranial pressure, CSF circulatory disturbances, head injuries, cerebrovascular disorders, and other illnesses allowed for the clear establishment of normal ICP limits, the rapid recognition of pathological pressure changes, the evaluation of therapeutic effects, and also an improvement in the comparability between new measurements and previous recordings. Simultaneously performed on-line evaluation of ICP recordings proved to be a practical means of monitoring both baseline values and therapeutic effectiveness.