title: Mathematical model for the hemodynamic response to venous occlusion measured with near-infrared spectroscopy in the human forearm.
abstract: We propose a mathematical model to describe the hemodynamic changes induced by a venous occlusion in a human limb. These hemodynamic changes, which include an increase in blood volume, a reduction in blood flow, and modifications to the oxygen saturation of hemoglobin, can all be measured noninvasively with near-infrared spectroscopy (NIRS). To test the model, we have performed NIRS measurements on the human forearm, specifically on the brachioradialis muscle, during venous occlusion induced by a pneumatic cuff inflated around the upper arm to pressures within the range 10-60 mmHg. We have found a good agreement between parameters measured by NIRS (total hemoglobin concentration and hemoglobin saturation) and the corresponding model parameters (capacitor voltage and arterial/capillary branch current). In particular, model and experiment indicate that the time constant for blood accumulation during venous occlusion (approximately 73-79 s) is much slower than the time constant for blood drainage following cuff release (approximately 5 s). These results indicate that this mathematical model can be a valuable analytical tool to characterize, optimize, and further develop diagnostic measurement schemes that use venous occlusion approaches.
authors.affiliation: Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA.
authors.forename: Toi Van
authors.initials: TV
authors.lastname: Vo
authors.forename: Peter E
authors.initials: PE
authors.lastname: Hammer
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Hoimes
authors.forename: Shalini
authors.initials: S
authors.lastname: Nadgir
authors.forename: Sergio
authors.initials: S
authors.lastname: Fantini
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000465:Algorithms; D001783:Blood Flow Velocity / Q000502:physiology*; D003198:Computer Simulation; D003936:Diagnosis, Computer-Assisted / Q000379:methods; D005542:Forearm / Q000098:blood supply / Q000502:physiology*; D006801:Humans; D008955:Models, Cardiovascular; D010092:Oximetry / Q000379:methods*; D010991:Plethysmography / Q000379:methods*; D014680:Veins / Q000502:physiology*; D014690:Venous Pressure / Q000502:physiology*