Cerebral microcirculation in neurointensive care patients: An observational and comparative analysis of laser Doppler flowmetry signals and clinical monitoring data

Multimodal monitoring is used in the neurointensive care unit (NICU) to avoid further brain injury in patients with subarachnoid haemorrhage (SAH). The aims were to investigate cerebral microcirculation in patients with SAH using laser Doppler flowmetry (LDF), and to compare LDF data with intracranial pressure (ICP) and mean arterial pressure (MAP). An LDF system with an in-house developed two-channel fibre optical probe and software was used for bedside monitoring of microvascular CBF ( Perf ) in seven patients. Analyses of mean, peak-to-peak amplitude and frequency variations were performed on selected data based on protocol information. Analysis of frequency variations focused on vasomotion. Data comparisons were evaluated on longer timescales using Pearson correlation and on shorter timescales using a moving correlation index. Microvascular data were successfully recorded for up to 10 days, resulting in 274 h of artefact-free data. The average perfusion ranged from 91 ± 29 a.u. to 424 ± 242 a.u. across patients and channels. Vasomotion was observed in 7–37 % and 4–44 % in the Perf and ICP data, respectively, with spatial, temporal, and interpersonal variations. Occasional positive and negative correlations between Perf and clinically monitored data were found on shorter timescales. Correlations varied daily among all individuals, confirming the need for moving indices to track correlation over time. Combining vasomotion analysis and correlations with clinical data can increase the knowledge about the underlying mechanisms of blood flow regulation in the injured brain in SAH patients.