Assessing the Accuracy and the Impact of Standard-practice Ventricular Drainage on Intracranial Pressure Measurements Following Traumatic Brain Injury

Traumatic brain injury (TBI) is a leading cause of death following injury in civilian populations and is a major cause of death and disability in combat casualties. While primary brain injury cannot be reversed, the management of severe TBI focuses on the mitigation of secondary injury mechanisms which occur as part of the downstream effects of the primary damage to the brain. Many secondary injury mechanisms are manifested clinically as elevated intracranial pressure (ICP) and cerebral perfusion pressure (CCP). This level and duration of elevated ICP is strongly associated with poor long term patient outcome.

Currently, there are two invasive techniques that are used at our facility for monitoring ICP and CPP. The first method requires the placement of an intra-parenchymal fiberoptic pressure monitor (IPM), also known as a camino, into the brain tissue that measures and displays ICP continuously. The second method requires placement of an extracranial ventricular drain (EVD) which both measures ICP when it is closed or clamped and also allows for therapeutic drainage of cerebral spinal fluid (CFS) to reduce pressure within the skull when it is open.

While clinical practices vary greatly across institutions, current clinical practice at our institution when using the EVD for ICP management is to allow continuous therapeutic CSF drainage and to manually close the drain for ICP assessment on an hourly basis. However, in a retrospective of study of TBI patients at our institution with simultaneous IPM and EVD placement, a spike in ICP was noted to correspond with the clamping of the EVD which often remained elevated for 15-30 minutes before returning to baseline. Due to the strong association between poor patient outcome and elevated ICP, this finding is alarming. These findings have important implications for procedures to not only treat elevated ICP, but also prevent potentially harmful intermittent elevations in ICP. Therefore, this study seeks to prospectively investigate the association between EVD clamping and elevated ICP.

Specifically, this study has 2 main objectives:

1. Evaluate the need for an optimized device that can simultaneously measure intracranial pressure and drain CSF without requiring potentially harmful clamping.
2. Provide data in support of retaining or modifying current clinical practices regarding intermittent versus continuous monitoring during periods of therapeutic drainage of CSF.