Simultaneous transients of intracranial pressure and heart rate in traumatic brain injury: Methods of analysis

Objectives: The detection of increasing intracranial pressure (ICP) is important in preventing secondary brain injuries. Before mean ICP increases critically, transient ICP elevations may be observed. We have observed ICP transients of less than 10 min duration,which occurred simultaneously with transient increases in heart rate (HR). These simultaneous events in HR and ICP suggest a direct interaction or communication between the heart and the brain. Methods: This chapter describes four mathematical methods and their applicability in detecting the above heart–brain cross-talk events during long-term monitoring of ICP. Results: Recurrence plots, cross-correlation function and wavelet analysis confirmed the relationship between ICP and HR time series. Using the peaks detection algorithm with a sliding window approach we found an average of 37 cross-talk events (± SD 39). The number of events detected varied among patients, from 1 to more than 150 events. Conclusion: Our analysis suggested that the peaks detection algorithm based on a sliding window approach is feasible for detecting simultaneous peaks, e.g. cross-talk events in the ICP and HR signals.