Plateau waves in head injured patients requiring neurocritical care

Object: Plateau waves often develop in neurointensive care patients. They are sudden increases in intracranial pressure (ICP) that lead to dramatic decreases of cerebral perfusion pressure (CPP) and can therefore contribute to ischemic secondary brain insult. The aim of this study was to analyze the occurrence of plateau waves in head injured patients requiring neurocritical care, their relation with cerebral autoregulation and impact on outcome. Methods: Data were analyzed retrospectively in 444 head injured patients admitted to Neuroscience Critical Care Unit of Addenbrooke's Hospital in Cambridge, UK. Arterial blood pressure (ABP), intracranial pressure (ICP), heart rate (HR) were digitally recorded and derived indices calculated. Primary monitoring data, autoregulation indices, outcome of patients, initial CT findings (in a subgroup of patients), brain tissue monitoring data (in a subgroup) were compared between patients who developed plateau waves and those who did not. Results: Plateau waves were observed in 109/444 patients (24.5%). They were significantly more frequent in younger patients. Impaired cerebrovascular pressure reactivity and depleted compensatory reserve were associated with vasodilatation on the top of the wave. Plateau waves were not associated with poorer outcome unless the episodes lasted for a long time (longer than 30-40 min). Plateau waves were more frequently seen in patients with lesser midline shift, lower volume of contusion on CT scan, absence of skull fractures, and lower brain tissue concentration of carbon dioxide. Conclusions: Plateau waves are frequent phenomenon. They are not associated with worse outcome unless they lead to sustained intracranial hypertension.