Advanced Physiologic Monitoring at the Site of Spinal Cord Injury
Abstract
One of the only treatment options for acute spinal cord injury (SCI) patients is augmenting blood pressure to maintain blood supply to the injured spinal cord. Proper hemodynamic management of acute SCI in the first week post-injury is critical for minimizing further secondary ischemic damage. It has been shown that even slight differences in average blood pressure can influence whether an acute SCI patient improves from being completely paralyzed to incompletely paralyzed. Equally, intriguing data has indicated that while an increase in blood pressure for one patient might improve their spinal cord blood flow, such an increase might not be sufficient for another patient, or conversely, maybe too high, and harmful. Adhering to simple guidelines that suggest a target blood pressure that should be maintained in all patients might improve outcomes in some but worsen it in others. What is lacking for clinicians treating acute SCI patients is a safe measurement tool that provides information in real time about the spinal cord blood supply and oxygenation and allows them to know if their efforts to elevate blood pressure are actually improving (or worsening) the injured spinal cord. Such a tool would provide information to guide clinicians in their treatment decisions and allow them to personalize and optimize the hemodynamic management of acute SCI patients. Supported by a fiscal year 2015 (FY15) Spinal Cord Injury Research Program (SCIRP) Translational Research Award (TRA), our research team at the University of British Columbia has recently developed an optical sensor that utilizes a novel near-infrared spectroscopy (NIRS) technique for monitoring tissue hemodynamics and oxygenation at the SCI site for up to seven days post-injury. This system includes a miniaturized NIRS sensor implanted on the dura over the SCI site at the time of surgical decompression, with the sensor cable externalized through the skin to allow for removal after seven days. The sensor is connected to a bedside NIRS controller that monitors, records, and visualizes changes in SC tissue oxygenated (O2Hb) and deoxygenated (HHb) hemoglobin concentrations, and measures, in real time, the tissue oxygenation index (TOI) using a mathematical algorithm. Supported by an FY20 SCIRP Clinical Trial Award, we are planning to test the safety, feasibility, and effectiveness of our developed NIRS system in a small pilot study of acute SCI patients. This clinical study, set to begin in September 2022, will allow us to perform the first-in-human NIRS measurements in SCI patients over the first seven days post-injury. To fully capitalize on this clinical opportunity, we seek to develop and test new advanced NIRS parameters, including the spinal cord tissue perfusion index (SCPI), a measure of regional tissue perfusion; and the spinal cord perfusion reactivity index (SCPRx) and the spinal cord oxygenation reactivity index (SCORx), two measures of tissue hemodynamic autoregulation. Monitoring these reactivity measures would provide further information about the spinal cord physiologic status and help guide vigilant hemodynamic management of the spinal cord to improve clinical outcomes in acute SCI patients. The clinical value of cerebrovascular reactivity monitoring to optimize cerebral hemodynamic autoregulation has already been demonstrated in patients with traumatic brain injury. Continuous monitoring of hemodynamic autoregulation using reactivity indices allows for the identification of an optimal range of mean arterial pressure (MAP) that maximizes the response of cerebral hemodynamics to manipulation in blood pressure for any given patient, overcoming the practice and limitations of a one-size-fits-all management approach. Establishing such reactivity measures from the spinal cord tissue requires controlled manipulations of blood pressure and oxygenation (i.e., extensive physiological challenges such as MAP manipulations and hypoxia induction) whi
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 04, 2024
- Source ID
- HT94252310777
Entities
People
- Babak Shadgan
Organizations
- United States Army
- University of British Columbia