Object: In order to monitor cerebral autoregulation status, a software package was developed to calculate a cerebral autoregulation index (pressure reactivity index, PRx). The aim of this study is to evaluate whether the application of this methodology is feasible and useful in the clinical setting.
Design: Prospective observational study.
Setting: NeuroIntensive Care Unit (NICU) of a university-affiliated teaching hospital.
Patients and participants: Twenty-six consecutive patients admitted to NICU requiring intracranial pressure (ICP) and invasive arterial pressure (AP) monitoring.
Measurements and results: Patient's data were collected for a total of 902 h. Mean PRx was calculated utilizing 2 h time window. CPP-PRx distribution graphs were calculated from CPP of 20 to 110 mmHg using 10 mmHg intervals. Autoregulation was preserved in 18% observations (83/451) and deranged in 49% observations (220/451). In 33% observations (148/451), autoregulation could not be clearly defined (0 < PRx < 0.2). Even if no clinical protocol was developed, autoregulation status information inserted in clinical decision pathway influenced clinical management. Mean CPP, calculated at maximum and minimum ICP every 2 h interval, resulted different between groups with good and poor reactivity (67 +/- 17.6 and 85 +/- 20.0 mmHg, respectively, for autoregulating observations and 60 +/- 19.1 and 67 +/- 19.4 mmHg, respectively, for nonautoregulating observations, P < 0.001, independent samples t-test). PRx values were normally distributed.
Conclusions: Our study demonstrates that a daily bedside measure of cerebral autoregulation is feasible. PRx values can support clinicians in the identification of a targeted CPP in patients suffering from different intracranial pathologies and requiring an intensive monitoring.