ARTICLE IN BRIEF
A randomized study conducted in South America found that traumatic brain injury patients whose treatment was managed using imaging and clinical examination fared just as well as patients who had intracranial pressure monitoring that was aimed at maintaining pressure at 20 mm Hg or less.
A new study questions the value of using intracranial pressure monitoring (ICP) to direct the treatment of patients with traumatic brain injury.
ICP monitoring has long been considered the standard of care for patients with severe traumatic brain injury (TBI), even though evidence to support the approach is not conclusive.
The randomized study conducted in South America found that TBI patients whose treatment was managed using imaging and clinical examination fared just as well as patients who had ICP monitoring that was aimed at maintaining pressure at 20 mm Hg or less.
“Our results do not support the superiority of treatment based on intracranial-pressure monitoring over treatment guided by neurologic testing and serial CT imaging in improving short-term or long-term recovery in the general population of patients with severe traumatic brain injury,” the researchers concluded in the report published in the Dec. 27, 2012 edition of The New England Journal of Medicine.
The researchers stressed that their findings should not be construed as an argument against the use of intracranial pressure monitoring.
“The value of knowing the precise intracranial pressure is not being challenged here, nor is the value of aggressively treating severe traumatic brain injury being questioned,” the researchers wrote. “Rather our data suggest that a reassessment of the role of manipulating monitoring intracranial pressure as part of multimodality monitoring and targeted treatment of severe traumatic brain injury is in order.”
Randall M. Chesnut, MD, the study's lead author, told Neurology Today that even though guidelines from the Brain Trauma Foundation support the use of ICP monitoring, they also note that there is inadequate evidence to say whether such monitoring improves outcomes. Dr. Chesnut, professor of neurological surgery and orthopedic surgery at Harborview Medical Center of the University of Washington in Seattle, said the guidelines acknowledged the need for a randomized, controlled trial to test the efficacy of ICP monitoring to manage severe traumatic brain injury, but it was assumed that such a trial would be unethical because ICP is considered standard care.
An ethical rationale for doing the research presented itself, Dr. Chesnut said, when he discovered in the course of setting up another study that there were intensive-care specialists in Latin American countries who managed patients with severe traumatic brain injury without using ICP monitoring, even though the technology was available in their hospitals.
“They were unsure whether adding ICP monitoring would make their patients better,” he said.
With funding from the National Institutes of Health and other agencies, his research team enrolled 324 patients age 13 or older with severe traumatic brain injury at ICU units at four hospitals in Bolivia and two in Ecuador. The patients randomly assigned to the pressure-monitoring group had a monitor placed as soon as possible and were treated to maintain an intracranial pressure of less than 20 mm Hg. The group of patients who had imaging and clinical exams was treated using a set protocol.
The primary outcome was calculated using a composite score based on factors such as survival time, impaired consciousness and functional status at three months and six months, and neuropsychological state at six months. The score could range from 0 (the worst) to 100 (the best).
The patients in the pressure-monitoring group had an average composite score of 56, compared with a score of 53 in the imaging-clinical exam group. Six-month mortality was 39 percent for the ICP monitoring group, compared with 41 percent for the other group. The median length of ICU stay was similar for the two groups — 12 days for the monitoring group and nine days for the imaging-clinical exam group, although the number of days of brain-specific treatments (such as administration of hyperosmolar fluids and use of hyperventilation) in the ICU was higher for the imaging-clinical exam patients.
“I think the paper is saying that we have been using a way too simplistic approach with ICP,” he said. “For instance, [maintaining intracranial pressure under] 20 mm Hg may not be the right number for every patient every day.”
J. Claude Hemphill III, MD, professor of neurology and neurological surgery at University of California, San Francisco, told Neurology Today that he considered the new research a “landmark study because it is the first clinical trial to really assess in a randomized way two different approaches to treating patients with possible elevated intracranial pressure after severe traumatic brain injury.” He said that as ICP monitoring became routine in most intensive-care units over the past decades, treatment of TBI patients became focused on maintaining intracranial pressure below 20 mm Hg, a somewhat arbitrary level defined in the guidelines.
“That number doesn't necessarily mean that all is well,” Dr. Hemphill said, noting, for instance, that even with a normal ICP reading there could be displacement of brain tissue or brain stem dysfunction.
Kevin Sheth, MD, assistant professor of neurology at the University of Maryland and a member of the editorial advisory board of Neurology Today, said the findings do not mean that intracranial pressure is not an important consideration for treating physicians, since elevated pressure can lead to impaired cerebral blood flow “and the end result of that process is brain death.” But he said the study suggests that ICP measures need to be considered in the context of other variables.
“This study should cause us to reflect on how we take of these patients,” he said. “Is the real goal to go after certain physiologic numbers or do we need to direct more of our efforts on the underlying disease process itself?”
An editorial accompanying the study noted that the relevancy of the results are bound to be questioned in part because the study was done in South America, not in a technology-rich country like the US. Also, many ICUs now use external ventricular drains, which allow drainage of spinal fluid to reduce pressure.
“Physiological measurements are inherently more appealing than clinical signs because they give the impression of precision and proximity to disease,” wrote Allan H. Ropper, MD, executive vice chair of neurology at Brigham and Women's Hospital in Boston. “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 dilation of the pupils indicate compression of the midbrain, and according to the study they are very suitable observations to use in directing treatment.”
Michel Torbey, MD, MPH, professor of neurology and neurological surgery at Ohio State University, said he did not think the study was the final word on ICP monitoring, noting that the sample size may not have been large enough to detect differences between management approaches. Nonetheless, he said the study is important because “it tells us that we shouldn't just be satisfied because the [ICP] number is 20 or below.”
Dr. Torbey said the study underscores the complexity of severe traumatic brain injury and the many factors that influence a patient's prognosis.