Raised intracranial pressure and low cerebral perfusion pressure are associated with ischaemia and poor outcome after brain injury. Therefore, many management protocols target these variables. However, there are no randomized controlled trials that have demonstrated the effectiveness of intracranial pressure-guided care in severely head-injured patients. Observational studies of such therapy have yielded inconsistent results, ranging from decreased mortality to no effect or increased morbidity or mortality. A recent cohort study supports the notion that the possible benefits of intracranial pressure monitoring after traumatic brain injury are small – if present – and would exceed a number needed for the treatment of 16. Furthermore, intracranial pressure monitoring and aggressive management of intracranial pressure and cerebral perfusion pressure have been associated with increased lengths of stay in the neurocritical care unit, conceivable costs and possibly an increased rate of complications. Against this background, there is sufficient clinical equipoise to warrant an adequately powered randomized controlled trial to compare intracranial pressure-guided care with supportive critical care without intracranial pressure monitoring in patients with severe traumatic brain injury. However, the realization of such a trial is likely to be problematic for a number of reasons, not least of which the firmly held biases of many clinicians.

This article will discuss the challenges related to the demonstration of the efficacy of monitoring in an intensive care environment. It will address interpretation, therapeutic intervention, sample size and compare efficacy to effectiveness in the context of the developing field of neurocritical care.