Assessing Early Microcirculatory Changes in Skeletal Muscle and Brain of a Rat Model of Sepsis with Hyperspectral Near-Infrared and Diffuse Correlation Spectroscopy
Abstract
Sepsis, an exaggerated immune response leading to multi-organ dysfunction, is responsible for 20% of global deaths, disproportionately affecting vulnerable and low-resource populations. Since early intervention is associated with increased survival, there is a need for accessible diagnostic technology. Microcirculatory impairment, manifesting as increased amplitude of vasomotion (i.e., low-frequency oscillations in microhemodynamics), occurs prior to systemic hypotension and organ injury. Near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS) are non-invasive optical tools capable of continuously quantifying microvascular hemoglobin content, oxygenation, and perfusion at the bedside. The objective of this thesis was to monitor the skeletal muscle and brain using NIRS and DCS in a rat model of early sepsis. The results revealed that while the brain is partly protected, perfusion to the skeletal muscle drops and the amplitude of vasomotion increases. Importantly, this thesis demonstrated the feasibility of NIRS and DCS for detecting early sepsis-related changes in microcirculatory regulation.