Occurrence of BPEs during ICP monitoring. In a prospective study, we examined the frequency and magnitude of BPEs in patients undergoing surveillance for SAH. Two Raumedic Neuro P sensors were placed nearby via the same burr hole in the skull. The different types of BPEs are illustrated. The trend plots in blue reveal differences in mean ICP computed for consecutive 6-second time windows (Mean ICPSignal 2 – Mean ICPSignal 1), and the green plots show differences in MWA (MWASignal 2 – MWASignal 1) of Signals 1 and 2, for the same 6-second time windows. The presence of PBEs is indicated by the differences in mean ICP, but with close to identical MWAs (differences in MWA < 0.5 mmHg). The red arrows indicate occurrence of BPEs. These plots are from different individuals. Type 2 BPE is shown in (a) and (b), while various examples of Type 3 BPEs are presented in (c), (d), (e) and (f).