Using Hyperspectral Near-Infrared Spectroscopy and Diffuse Correlation Spectroscopy to Monitor the Effects of Phenylephrine in the Microcirculation

Laura Mawdsley, The University of Western Ontario

Abstract

The microcirculation is the site of oxygen exchange in the body, and little work has been done to determine if different microvascular beds respond similarly to a simultaneous vascular challenge. A hybrid microvascular monitoring device was developed that uses hyperspectral near-infrared spectroscopy and diffuse correlation spectroscopy to simultaneously monitor the brain and skeletal muscle. Experiments were conducted on Sprague Dawley rats (n=6, 156g±6.4g) to discern the effect that phenylephrine (0.1 mL bolus, 10 mg/kg) has on the mean arterial pressure (MAP), hemoglobin concentration, and blood flow in each microvasculature. Hemoglobin concentration increased by 2.1±0.2 mmol in the brain, and decreased by 2.5±1.0 mmol in skeletal muscle. Cerebral blood flow increased by 20.8±7.2% while muscular blood flow decreased by 7.5±1.5%. The response in the brain was dependent on the initial baseline MAP. This non-invasive method can be used to aid in clinical translation of findings in animal models.