Brain Tissue Oxygen Monitoring in Traumatic Brain Injury (TBI)

Overview

Traumatic brain injury (TBI) is a major cause of death and disability, with an estimated cost of 45 billion dollars a year in the United States alone. Every year, approximately 1.4 million sustain a TBI, of which 50,000 people die, and another 235,000 are hospitalized and survive the injury. As a result, 80,000-90,000 people experience permanent disability associated with TBI. This project is designed to determine whether a device designed to measure brain tissue oxygenation and thus detect brain ischemia while it is still potentially treatable shows promise in reducing the duration of brain ischemia, and to obtain information required to conduct a definitive clinical trial of efficacy. A recently approved device makes it feasible to directly and continuously monitor the partial pressure of oxygen in brain tissue (pBrO2). Several observational studies indicate that episodes of low pBrO2 are common and are associated with a poor outcome, and that medical interventions are effective in improving pBrO2 in clinical practice. However, as there have been no randomized controlled trials carried out to determine whether pBrO2 monitoring results in improved outcome after severe TBI, use of this technology has not so far been widely adopted in neurosurgical intensive care units (ICUs). This study is the first randomized, controlled clinical trial of pBrO2 monitoring, and is designed to obtain data required for a definitive phase III study, such as efficacy of physiologic maneuvers aimed at treating pBrO2, and feasibility of standardizing a complex intensive care unit management protocol across multiple clinical sites. Patients with severe TBI will be monitored with Intracranial pressure monitoring (ICP) and pBrO2 monitoring, and will be randomized to therapy based on ICP along (control group) or therapy based on ICP in addition to pBrO2 values (treatment group). 182 participants will be enrolled at four clinical sites, the University of Texas Southwestern Medical Center/Parkland Memorial Hospital, the University of Washington/Harborview Medical Center, the University of Miami/Jackson Memorial Hospital, and the University of Pennsylvania/Hospital of the University of Pennsylvania. Functional outcome will be assessed at 6-months after injury.

Design and Outcomes This study is a two-arm, single-blind, randomized, controlled, phase II, multi-center pilot trial of the efficacy of pBrO2 monitoring, and is designed to obtain data required for a definitive phase III study, such as efficacy of physiologic maneuvers aimed at normalizing pBrO2. 182 patients with severe TBI who require ICP monitoring will be recruited into this study at 4 clinical sites in the US (Univ. of Texas Southwestern/Parkland Memorial Hospital, Univ. of Washington/Harborview Medical Center, Univ. of Miami/Jackson Memorial Hospital, and Univ. of Pennsylvania/Hospital of the Univ. of Pennsylvania). All patients will have both ICP monitors and pBrO2 monitors inserted through the same burr hole. Half of the patients will be randomized to a treatment protocol based on both ICP and pBrO2 readings, while the control group will be randomized to a treatment protocol based only on ICP readings. The pBrO2monitors of the control arm will be masked, so that the treating physicians will be unaware of the pBrO2 information. Patients will have telephone follow-up interview to assess their level of recovery 6 months post injury, using the Glasgow Outcome Scale-Extended. Interventions and Duration Patients randomized to the control group will have pBrO2 implanted in a similar fashion as patients in the treatment group, but after calibration of the device, the display will be covered with opaque tape. Patients in the control will be treated with a protocol based on ICP measures only. Patients in the treatment group (both ICP and pBrO2 measures are visible) will be treated according to a protocol that incorporates both ICP and pBrO2 measures. The treatment protocols are based on current standards of care, but are described in detail to insure uniformity in treatments across the 4 study sites. The probe will remain in place for a maximum or 5 days, until all values are normal for 48 hours, or sooner if a complication arises. If the patient has normal values, monitors will be removed after 48 hours. Objectives Primary Objective: The prescribed treatment protocol, based on pBrO2 monitoring, results in reduction of the fraction of time that brain oxygen levels are below the critical threshold of 20 mm Hg in patients with severe traumatic brain injury. Secondary Objectives: * Safety hypotheses: Adverse events associated with pBrO2 monitoring are rare. * Feasibility hypotheses: Episodes of decreased pBrO2 can be identified and treatment protocol instituted comparably across 4 clinical sites, and protocol violations will be low (\<10%) and uniform across different clinical sites. * Non-futility hypothesis: A relative risk of good outcome measured by the Glasgow Outcome Scale-Extended 6 months after injury of 2.0 is consistent with the results of this phase II study.