Figure 3

(a) The power spectrum of the pressure difference in an accepted 6-minute window from patient 1 after noise removal. Two peaks are evident, one related to the cardiac cycle (~1.1 Hz) and one related to the respiratory cycle (~0.2 Hz). Low frequencies (<0.1 Hz) are not shown. (b) Average dICP amplitude for each patient, cardiac vs respiratory. All patients had lower respiratory amplitudes on average. (c) Average cardiac dICP amplitude for each patient during the awake and sleeping state. Although some variations were found from patient to patient, no clear trend was evident.