A synopsis of brain pressures: which? when? are they all useful?

Abstract

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.

Discussion: 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.