Automatic calculation for pulse wave morphology change: a rheoencephalographic study

Abstract

Abstract Purpose The intracranial pressure (ICP) pulse waveform morphological alteration indicates the decreasing intracranial compliance/elevation of ICP by increasing the amplitude of the second peak (P2). It is useful information at the bedside, but its invasive nature is a problem. It was demonstrated that a noninvasive method, called rheoencephalography (REG), correlates with ICP. We compared the correlation of the new program calculating automatically the P2 change to manually calculated results. Methods REG was measured in 19 healthy volunteers. Pulse waves were recorded with a 200 Hz sampling rate on a laptop. Measurements were made by cursor operation and with a MATLAB script developed for the automated calculation of P2 amplitudes on 10 pulse waves during control and head-down tile (HDT) positions. Results During the HDT position, the P2 amplitude increased. Manual reading resulted in a significant difference in the female group (P = 0.0007) and the male group (P < 0.0001). With automated analysis, the REG P2 increase was significant, and the ratios were 4/5 (80%) for females and 10/14 (71%) for males. Conclusion The significance difference can be interpreted as follows: the manual P2 reading was clearer from artifacts than the automated calculation, which involved all lengths of the HDT position time, while the manual reading involved only 10 artifact-free P2 values. We initiated a study in which ICP and REG are recorded together, and it will be possible to compare their correlation. Such confirmation opens the use of REG in neurocritical care monitoring, space research, and military applications.