What Determines Outcome in Patients That Suffer Raised Intracranial Pressure After Traumatic Brain Injury?

INTRODUCTION: Episodes of raised intracranial pressure (ICP) after traumatic brain injury (TBI) are responsible for the majority of secondary brain injury events and thereby strongly affect long-term outcome. However, not all patients with major episodes of raised ICP suffer a poor outcome. The aim of the current analysis was to identify variables contributing to good outcome in patients suffering episodes of high ICP. METHODS: Retrospective analysis of 20 severe TBI patients admitted to the University Hospitals Leuven between 2010 and 2014. All patients had at least one episode of ICP > 30 mmHg for more than 3 min in succession. Outcome was assessed by the extended Glasgow Outcome Scale at 6 months. Partial least squares (PLS) regression was used to derive factors determining outcome. Pressure reactivity index (PRx) was calculated as an index for cerebrovascular autoregulation capacity. RESULTS: Both outcome groups did not differ for age, Glasgow Coma Score, pupil reactivity, computed tomography Marshall classification, glycaemia, haemoglobin and CRASH and IMPACT scores on admission. Significant differences were found for mean ICP, number of episodes of ICP > 30 mmHg, number and duration of longest PRx episodes. The number of episodes of ICP > 30 mmHg correlated significantly with the number and duration of longest PRx episodes. PLS regression indicates that episodes of impaired autoregulation contributed equally to explaining outcome compared to episodes of raised ICP. CONCLUSIONS: Prolonged episodes of disturbed dynamic cerebral autoregulation contribute to detrimental outcome in patients with increased ICP. Autoregulation seems to have an important protective role in tolerating episodes of raised ICP.

Comparison of Intracranial Pressure and Pressure Reactivity Index Obtained Through Pressure Measurements in the Ventricle and in the Parenchyma During and Outside Cerebrospinal Fluid Drainage Episodes in a Manipulation-Free Patient Setting.

OBJECTIVE: We investigated the effect of cerebrospinal fluid (CSF) drainage on the intracranial pressure (ICP) signal measured in the parenchyma and the ventricle as well as the effect on the pressure reactivity index (PRx) calculated from both signals. METHODS: Ten patients were included in this prospective study. All patients received a parenchymal ICP sensor and an external ventricular drain (EVD) for CSF drainage. ICP signals (ICP-p and ICP-evd) were captured. Part of the study was a period of 90 min during which the patient was free from any manipulation, consisting of 30 min of drainage (O1), 30 min EVD closed (C) and 30 min of drainage (O2). RESULTS: Mean ICP-evd and mean AMP-evd increased (3.03 and 0.46 mmHg) from O1 to C and decreased (2.12 and 0.43 mmHg) from C to O2. ICP-p and AMP-p changes were less pronounced (closing EVD: +0.81 mmHg/+0.22 mmHg; opening EVD: -0.22 mmHg/-0.05 mmHg). Mean difference between PRx-evd and PRx-p was 0.12 for O1, 0.02 for C and -0.02 for O2. The intraclass correlation coefficient for absolute agreement of single measures was 0.66 for O1, 0.77 for C and 0.69 for O2. Mean PRx differences demonstrated a significant difference between O1 versus C and O1 versus O2 but not between C versus O2. CONCLUSION: Drainage of CSF reduces ICP magnitude and amplitude through the EVD. This effect was only marginal in parenchymal ICP measurements. In manipulation-free circumstances, agreement of PRx obtained through parenchymal and ventricular measurements was moderate to good, depending on the statistical method, and was not necessarily influenced by drainage.