Researchers Pursue Fast, Safe Way to Test Brain Pressure

Ohio State University medical researchers have taken the first steps toward evaluating a new protocol for quick detection of elevated brain pressure in critically ill or injured patients in hospital emergency departments. If the method proves safe and effective in additional studies, doctors will have a faster, less invasive way to determine some patients? need for medical intervention to reduce the damaging and sometimes fatal effects of elevated brain pressure.

Researchers hope to demonstrate that elevated brain pressure in trauma patients can be detected through a noninvasive procedure by which eye pressure measurements are obtained using a portable, hand-held instrument. Initial studies suggest changes in eye, or intraocular, pressure correlate strongly with changes in brain pressure, but more research is needed to confirm a pilot study?s findings.

That study, published in a recent issue of the journal Annals of Emergency Medicine, suggested that abnormal eye pressure measured with a handheld tonometer is an indicator of abnormal intracranial pressure in patients already being monitored for elevated brain pressure, said Dr. Brian Hiestand, an emergency medicine physician at The Ohio State University Medical Center and senior author on the study.

?In our small sample, everybody who had normal brain pressure on the monitor had normal eye pressure, and everybody with abnormally elevated brain pressure also had abnormally elevated eye pressure,? Hiestand said.

In the study, researchers secured family permission to measure eye pressure in patients in intensive care settings who were being treated with an invasive intracranial pressure monitor that allows for real-time monitoring of brain pressure as well as relief of pressure by drainage of cerebrospinal fluid. Twenty-seven patients were enrolled, and 76 simultaneous brain and eye measurements were performed. A tonometer is a device resembling a pen that can be applied directly to the eye, which is numbed for the procedure, to measure hydrostatic pressure.

Doctors now are designing a study they hope to conduct in an emergency department setting to further test the hypothesis. ?The question still remains whether we would see the same results in patients whose brain pressure is not already being monitored or regulated,? Hiestand said. ?We also don?t know how the rate of change of intraocular pressure compares to the rate of change of intracranial pressure.?

The incentive is strong to add a reliable noninvasive brain pressure measurement to trauma management, Hiestand said, because ?the sooner and more aggressively we can manage pressure in the brain, the better the patient is going to do.?

Currently, the only way to obtain a measurement of intracranial pressure on an unconscious patient is to insert a monitor through the skull into the brain, a highly specialized neurosurgical procedure typically done in an intensive care setting and only on rare occasions performed in emergency departments.

?Being able to avoid this invasive procedure is preferable if we can reliably differentiate between normal brain pressure and elevated intracranial pressure,? Hiestand said. ?We typically can?t examine trauma patients for neurological symptoms because we anesthetize them if they are critically injured or ill.?

The most common causes of acute elevated brain pressure are stroke, brain injury or infection. If elevated pressure is left untreated and brain tissue is displaced by excess fluid or blood, the herniation of brain tissue outside the skull is almost always fatal, Hiestand said.

Hiestand co-authored the study with Drs. Matthew Lashutka, Abhinav Chandra and Holt Murray, all former resident physicians at OSU Medical Center, and Gary Phillips of Ohio State?s Center for Biostatistics.

Added: 1.31.05