Novel Noninvasive Methods of Intracranial Pressure and Cerebrovascular Autoregulation Assessment: Seeing the Brain Through the Eyes
Abstract
Traumatic brain injury (TBI) has been dubbed the "silent epidemic" in the United States because of missed diagnoses and the often unnoticed associated complications with lasting neurological effects. TBI is a major public health problem as well as a major source of morbidity and mortality among both civilians and military personnel. It is implicated in in approximately 30% of injury-related civilian deaths in the U.S. and has been reported in over 34,000 combat injuries since 2000. The significance of such injuries becomes apparent with the military s increased focus on prolonged field care (PFC) and prolonged damage control resuscitation (pDCR). Approximately, 20% of TBI patients will suffer a serious decline in medical condition during the first 72 hours (the window for PFC) due to increased pressure within the brain, reduced blood flow, and subsequent inflammation and ischemia leading to devastating and long-lasting secondary injuries, disabilities, and even death. Monitoring of intracranial pressure (ICP) and cerebral autoregulation (CAR) are significant management strategies used in the treatment of TBI and are usually aimed at preventing secondary brain damage. However, due to the need for invasive measures requiring a high level of experience, technologies and monitoring modes currently available to evaluate CAR and ICP are not suitable for use and application in early echelons of care, especially in an austere environment such as the battlefield,. Development of noninvasive methodologies and devices to monitor and assess CAR and ICP would allow for early application by combat medics, first responders, emergency departments, surgeons, and critical care staff. Improvement in screening and monitoring methods will provide a significant benefit to patients if combat medics on the front lines are equipped with the tools necessary for earlier detection of life-threatening TBI and formulation of informed management decisions. The proposed project aims to employ ocular bioimpedance and ultrasound in a novel manner to assess CAR and ICP, utilizing the eye as a window to the brain. Its main goals will be to use noninvasive ocular electrical bioimpedance methodologies to track dynamic changes in cerebral blood flow (CBF) and associated changes in cerebrovascular autoregulation, and to develop a computer image analysis algorithm capable of automating the analysis of images of the optic nerve sheath (ONS) obtained by ultrasound to evaluate ICP. Noninvasive, risk-free techniques to assess CAR and ICP performed at early time points in the care of the injured Warfighter may prove to have tremendous potential in guiding patient triage and management and improving outcomes. This clinical research study will utilize two animal models of TBI, as well as human subjects with cerebral injury (patients at the University of Michigan Health System [UMHS]). Large animal (swine) models will include one with TBI caused by blunt trauma and one designed to examine cerebral and systemic hemodynamics in response to various modulators of CBF (e.g., blood pressure, hemorrhage, elevations in ICP, and hyperventilation). The human studies will be non-interventional. Simultaneously, the project team will begin evaluation of ocular impedance as an indicator of CAR and ONS using ultrasound measurement videos for assessment of ICP in human patients who are also undergoing both invasive arterial blood pressure and ICP monitoring for brain injury in the Neurosurgical Intensive Care Unit. The bioimpedance information obtained will be compared to traditional cerebral monitoring techniques (ICP, cerebral perfusion pressure (CPP), and pressure reactivity index (PRx)). Results from a novel ultrasound video analytic to be developed through this project will be compared to expert ONS ultrasound interpretation by several clinicians, as well as invasively monitored ICP. This proposal will address Focus Area 2 of the Prolonged Field Care Resea
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 29, 2018
- Source ID
- W81XWH1810005
Entities
People
- Mohamad H Tiba
Organizations
- United States Army
- University of Michigan