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.