We have sought to develop an automated methodology for the continuous updating of optimal cerebral perfusion pressure (CPPopt) for patients after severe traumatic head injury, using continuous monitoring of cerebrovascular pressure reactivity. We then validated the CPPopt algorithm by determining the association between outcome and the deviation of actual CPP from CPPopt.
Retrospective analysis of prospectively collected data.
Neurosciences critical care unit of a university hospital.
A total of 327 traumatic head-injury patients admitted between 2003 and 2009 with continuous monitoring of arterial blood pressure and intracranial pressure.
Arterial blood pressure, intracranial pressure, and CPP were continuously recorded, and pressure reactivity index was calculated online. Outcome was assessed at 6 months. An automated curve fitting method was applied to determine CPP at the minimum value for pressure reactivity index (CPPopt). A time trend of CPPopt was created using a moving 4-hr window, updated every minute. Identification of CPPopt was, on average, feasible during 55% of the whole recording period. Patient outcome correlated with the continuously updated difference between median CPP and CPPopt (chi-square = 45, p < .001; outcome dichotomized into fatal and nonfatal). Mortality was associated with relative “hypoperfusion” (CPP < CPPopt), severe disability with “hyperperfusion” (CPP > CPPopt), and favorable outcome was associated with smaller deviations of CPP from the individualized CPPopt. While deviations from global target CPP values of 60 mm Hg and 70 mm Hg were also related to outcome, these relationships were less robust.
Real-time CPPopt could be identified during the recording time of majority of the patients. Patients with a median CPP close to CPPopt were more likely to have a favorable outcome than those in whom median CPP was widely different from CPPopt. Deviations from individualized CPPopt were more predictive of outcome than deviations from a common target CPP. CPP management to optimize cerebrovascular pressure reactivity should be the subject of future clinical trial in severe traumatic head-injury patients.
From the Division of Neurosurgery (MJHA, MC, KPB, AL, AGK, PJH, JDP, PS), Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK; Department of Neurology (MJHA), University of Groningen, University Medical Centre Groningen, Groningen, The Netherlands; Department of Anaesthesia (LAS), Lausanne University Hospital, Lausanne, Switzerland; Neurosciences Critical Care Unit (AL, DKM), Addenbrooke’s Hospital, Cambridge, UK; and Department of Anesthesiology and Critical Care Medicine (KMB), Texas Children’s Hospital, Houston, TX.
*See also p. 2526.
The software for brain monitoring ICM+ (http://www.neurosurg.cam.ac.uk/icmplus) is licensed by the University of Cambridge (Cambridge Enterprise). Mr. Czosnyka and Mr. Smielewski have a financial interest in a part of the licensing fee. Dr. Aries received a travel grant from the European Federation of Neurological Societies (EFNS), and is supported by the Netherlands Organisation for Health Research and Development. Dr. Steiner is supported by a grant from the Swiss National Science Foundation. Dr. Kolias is supported by an National Institute for Health Research (NIHR) Academic Clinical Fellowship and a Raymond and Beverly Sackler Studentship. Mr. Hutchinson is supported by an Academy of Medical Sciences/Health Foundation Senior Scientist Fellowship and grants from the Medical Research Council/NIHR. Mr. Menon is supported by funding from the Medical Research Council, the NIHR Cambridge Biomedical Centre, and an NIHR Senior Investigator award. Mr. Pickard is a NIHR senior investigator awardee and a principal investigator within the NIHR Biomedical Research Centre (Cambridge University Hospital Foundation Trust) and lead principal investigator for the Medical Research Council “Acute Brain Injury Programme” grant. The authors acknowledge great support from Addenbrooke’s Hospital Neurocritical Care Unit staff and Academic Neurosurgical Unit registrars, without whose help the collection of computerized data never would have succeeded. The remaining authors have not disclosed any potential conflict of interest.
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