Challenge to brain injury guideline care

By Eleanor McDermid, Senior medwireNews Reporter

A randomized controlled trial has cast doubt on whether it is necessary to routinely place an intraparenchymal pressure monitor in patients with severe traumatic brain injury (TBI).

Mortality, length of stay in the intensive care unit (ICU), and adverse events did not differ according to whether patients had a monitor placed or were managed according to imaging and clinical findings, show the findings in The New England Journal of Medicine.

"At issue here is not the question of whether intracranial pressure is important - both groups were treated for intracranial hypertension," say lead researcher Randall Chestnut (University of Washington, Seattle, USA) and colleagues. "We investigated whether the guidelines-based protocol used in this study significantly improved the outcome."

The protocol involved fitting patients with a pressure monitor and maintaining pressure below 20 mmHg, and the team had hypothesized that it would indeed improve outcomes. This being embedded in the guidelines made a randomized trial difficult to justify; however, Chestnut et al identified a number of intensivists in Bolivia and Ecuador who routinely treated patients according to clinical and imaging signs, despite the availability of monitors.

There were 324 patients in the study. Those assigned to the clinical-imaging group received a fixed dose and schedule of hyperosmolar therapies, with optional mild hyperventilation, and additional treatments given in the face of continuing edema, deteriorating neurologic condition, or clinical signs of intracranial hypertension.

At 6 months, 41% of this group had died, as had 39% of the monitoring group - the difference was nonsignificant. There was also no difference on the primary trial outcome, which was a composite score based on 21 measures of functional outcome, with scores (best score 100) of 53 in the clinical-imaging group and 56 in the monitoring group.

The length of ICU stay was similar between the groups, at 9 and 12 days for the clinical-imaging and monitoring groups, respectively. The clinical-imaging group received significantly more brain-specific treatments than the monitoring group, but the team believes this simply reflects use of a fixed dosing schedule.

In an editorial accompanying the study, Allan Ropper (Brigham and Women's Hospital, Boston, Massachusetts, USA) points out that, although considered mandatory, measuring intracranial pressure does not indicate which particular parts of the brain are becoming compressed, yet this partly determines patient outcomes. Intracranial pressure and brain-stem compression are "parallel but disparate indicators" of increasing brain volume, notes Ropper. "Treating one does not consistently improve the other."

He says: "We are still likely to continue to doubt clinical signs, which indeed do not reflect global pressure inside the cranium; but stupor, coma, posturing, and dilatation of the pupils indicate compression of the midbrain, and according to this study they are very suitable observations to use in directing treatment."

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