He isn’t wearing a helmet and arrives at the hospital minimally responsive with a Glasgow Coma Score of 5. He is emergently intubated. A CT scan of his brain reveals swelling and diffuse injury. He is transferred to the neurologic intensive care unit to manage his traumatic brain injury.
How to monitor the swelling within his brain and tailor his treatment? Current guidelines suggest the use of intracranial pressure (ICP) monitoring. Despite a lack of randomized controlled trials testing whether it’s necessary to obtain these invasive numbers, the use of an ICP monitor has become standard of care.
However, a study published in this week’s issue of NEJM calls into question the necessity of ICP monitoring, suggesting instead that for some patients, decisions based on clinical criteria might be sufficient.
In this study, Randall Chesnut, M.D. and colleagues randomized 324 patients with severe traumatic brain injury to one of two protocols: management based on ICP pressure monitoring, or treatment tailored by clinical exam and imaging criteria.
Of note, the study was performed in Bolivia and Ecuador, in hospitals where the intensive care physicians routinely managed traumatic brain injury without invasive monitoring. It wouldn’t have been ethical, the authors point out, to randomize patients in US intensive care units (where this monitoring is the standard of care) to go without.
Once enrolled, patients randomly assigned to the pressure-monitoring group had a catheter placed into the brain tissue, and were treated to maintain the generally-accepted goal pressure of less than 20 mm Hg. The other group, in contrast, were treated based on signs of intracranial hypertension on imaging or clinical exam. The interventions employed included hyperosmolar therapy, hyperventilation or ventricular drainage, if that was deemed necessary.
These were sick patients; close to 40% in each group had midline shift detected on their initial CT scan, and nearly all had signs of intracranial hypertension.
Did the invasive monitoring matter? The primary outcome – a composite measure based on survival time, functional and clinical status – revealed no difference between the two groups. Adverse events were similar, as was median stay in the ICU.
In their discussion, the authors point out that this study does not in any way negate the importance of intracranial pressure in management of traumatic brain injury – instead, they note, the data call into question the need to base treatment on ICP monitoring rather than clinical exam and imaging. They therefore conclude by encouraging “a reassessment of the role of manipulating monitored intracranial pressure.”
In an accompanying editorial, neurologist Allan Ropper anticipates and addresses potential objections to the study’s conclusions. He likens ICP monitoring to wedge pressure monitoring, no longer a standard of care to dictate fluid management in medical ICUs. He notes that despite the possible weaknesses inherent in the study’s location, and composite endpoint, the conclusion stands that “measurement makes little difference in terms of reducing the early damage caused by elevated intracranial pressure.”
Back to our patient: intracranial pressure monitoring, or no? Until we develop more specific tools to detect early danger signs of brain stem compression, Ropper writes: “clinical methods are fine.”