A synopsis of brain pressures: which? when? are they all useful?
OBJECTIVE
In addition to intracranial pressure (ICP) and cerebral perfusion pressure (CPP), there are many more brain-related measures defined as 'pressures'. Cerebral intra-tissue pressure, critical closing pressure, 'optimal' CPP, non-invasive CPP (nCPP) and non-invasive ICP (nICP), interhemispherical pressure gradients are the modalities which currently attract more attention in the management of head injured patients.


METHODS
This review summarizes the most important points related to the 'brain pressures' applied in clinical practice, and it is based both on the literature and the authors' own experience.


RESULTS
While ICP and CPP monitoring remains the cornerstone of head injury management, derived pressures are gaining clinical significance. 'Optimization' of CPP provides a rational compromise between the 'Critical Closing Pressure-oriented protocol' and the 'Lund concept', and it allows individualized tailoring of cerebral hemodynamics. Non-invasive ICP and CPP are practical surrogates for invasive monitoring especially in the early stages of trauma management. CCP and pressure gradients are promising prognostication tools.


CONCLUSIONS
Most of the derived brain pressures cannot be assessed at the bedside without a dedicated computer tool. Some practical and theoretical aspects about the measurement, signal analysis, estimation process, accuracy and interpretation need further researching and refinement.
Czosnyka
Marek
M
Academic Neurosurgery Unit, Department of Neurosciences, University of Cambridge, Box 167, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK. MC141@medschl.cam.ac.uk
Smielewski
Peter
P
Lavinio
Andrea
A
Czosnyka
Zofia
Z
Pickard
John D
JD
D001794:Blood Pressure; D001795:Blood Pressure Determination / Q000379:methods; D001930:Brain Injuries / Q000150:complications / Q000503:physiopathology*; D002536:Cerebral Arteries / Q000503:physiopathology; D002560:Cerebrovascular Circulation; D006706:Homeostasis; D006801:Humans; D019586:Intracranial Hypertension / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology*; D007427:Intracranial Pressure; D008991:Monitoring, Physiologic / Q000379:methods