A Near Infrared Spectroscopy System for Assessing Rehabilitation on Peripheral Arterial Occlusion Patients

Abstract

Purpose: A near-infrared spectroscopy system was developed to evaluate peripheral arterial occlusive disease (PAOD). The wireless device can take measurements when patients are doing rehabilitation exercise. Methods: Two LED modules with wavelengths of 740 nm, 808 nm and 850 nm were placed over 32 mm away from the photodiode to detect the deep backscattering from muscle tissue. The absorbance difference from the extent of tissue oxygenation was extracted using a modified Beer’s law. Measurements taken on different muscle groups were applied to determine which branch of artery is occluded. Results: The changes in oxygenation of gastrocnemius and tibialis anterior muscle were recorded when PAOD patients were riding a stationary bicycle. The drop in oxygenation with exercise generally should recover within 15 min of continuing exercise. Otherwise, the artery is not capable to provide enough blood supply to the exercising muscles. Since gastrocnemius is the primary muscle used in biking exercise, the compensatory vasodilation in gastrocnemius leads to hypoperfusion in tibialis anterior muscle. Conclusion: This NIRS system is helpful for detecting the changes in tissue oxygenation during exercise. Muscle hypoxia was more obvious during exercise when the artery had some degree of occlusion.