NAPLES, Fla. – Episodes as brief as 5 minutes of severe intracranial hypertension and moderate to severe cerebral hypoperfusion were associated with worse outcome in patients with severe traumatic brain injury in a single-center analysis of 60 patients.
Dr. Deborah M. Stein
"Perhaps aggressive efforts to prevent these episodes, rather than merely react to them, are warranted," lead author Dr. Deborah M. Stein said at the annual meeting of the Eastern Association for the Surgery of Trauma.
Treatment of intracranial hypertension (ICH) and cerebral hypoperfusion (CH) is typically initiated only when certain thresholds are reached, and brief episodes are largely ignored. Even in the most efficient of ICUs, however, it takes more than 5 minutes to initiate and achieve successful therapy for these insults.
Manual end-hour recordings are traditionally used to document ICH and CH, but recent work has shown that continuous automated monitoring might detect more ICH and is more closely correlated with outcome than are manual end-hour recordings, said Dr. Stein, director of neurotrauma critical care and chief of trauma critical care at the University of Maryland Medical Center in Baltimore.
Using a continuous vital signs data recorder, the researchers captured vital sign waveforms every 6 seconds for 60 patients with a head Abbreviated Injury Scale score of 3 or greater (mean, 4.2) requiring intracranial pressure (ICP) monitoring at the shock trauma center. The 5-minute means were calculated for ICP, cerebral perfusion pressure (CPP), and episodes of combined insult, measured by the Brain Trauma Index (BTI). All traces were visually reviewed and confirmed by a physician.
At admission, the prospectively enrolled cohort had a mean Injury Severity Scale score of 28.5, a mean Marshall Scale score of 2.5, and a mean Glasgow Coma Scale score of 6.4. Their average age was 34 years (range, 16-83 years), 85% were male, and 97% had blunt trauma injuries.
Eight patients (13%) died within 30 days of hospitalization. In all, 37 patients had a favorable functional outcome (defined by a Glasgow Outcome Scale–Extended score of 5-8) at 6 months, and 23 patients, including the 8 who died, had a poor outcome (defined as a GOSE score of 1-4), Dr. Stein said.
Patients with poor functional outcome had a significantly greater number of brief, 5-minute episodes per day than did patients with a favorable outcome of intracranial pressure greater than 30 mm Hg (mean, 0.5 vs. 0.3), cerebral perfusion pressure less than 50 mm Hg (mean, 0.7 vs. 0.3), CPP less than 60 mm Hg (mean, 1.1 vs. 0.7), brain trauma index score of less than 2 (mean, 0.7 vs. 0.3), and BTI less than 3 (1.1 vs. 0.6).
"This study demonstrates that these brief episodes, previously thought to be relatively benign, may in fact play a significant role," Dr. Stein said.
Invited discussant Dr. Michael Ditillo, a surgeon from Yale University in New Haven, Conn., asked whether the brief episodes are a cause of or a marker for worse outcomes, and how the data have affected bedside management.
Dr. Stein said the retrospective nature of the analysis did not allow for demonstration of cause and effect, but she conjectured that the brief episodes of ICH and CH probably are markers of disease severity.
"The analogy that I make is that we don’t ignore episodes of hypoxia or hypotension in our patients, however brief," she said. "We don’t turn down the ventilator and check to see if the patient is hypoxic, but for some reason with brain injury, we do have that tendency."
As a result of the findings, Dr. Stein said she is more aggressive about trying to prevent these episodes, particularly in patients with poor intracranial compliance. Her strategy includes more aggressive management of sodium levels, continuous drainage of cerebrospinal fluid, and better sedation during bedside procedures.
In some situations, transient episodes of ICH and CH are almost a medical necessity, such as neurological "wake-up tests," sedation vacations, bedside or operative procedures, and extraventricular drain clamping. Yet to be determined is whether there is a subset of patients at higher risk of episodic insults for whom these procedures and examinations might be more detrimental than beneficial, Dr. Stein said.
Dr. Stein reported a U.S. Department of Defense grant. Dr. Ditillo reported no conflicts.