Tissue Oximeter with Selectable Measurement Depth Using Spatially Resolved Near-Infrared Spectroscopy

Distinct adaptations of muscle endurance but not strength or hypertrophy to low-load resistance training with and without blood flow restriction

Low-load resistance training promotes muscle strength and hypertrophic adaptations when combined with blood flow restriction (BFR). However, the effect of BFR on muscle endurance remains unclear. The aim of this study was to clarify the effects of BFR on muscle performance and adaptation, with special reference to local muscle endurance. In experiment 1, eight healthy men performed unilateral elbow flexion exercise to failure at 30% of one-repetition maximum with BFR (at 40% of estimated arterial occlusion pressure) and free blood flow (FBF). During the exercise, muscle activity and tissue oxygenation were measured from the biceps brachii. In experiment 2, another eight healthy men completed 6 weeks of elbow flexion training with BFR and FBF. The number of repetitions to failure at submaximal load (Rmax), the estimated time for peak torque output to decay by 50% during repetitive maximum voluntary contractions (half-time), one-repetition maximum, isometric strength and muscle thickness of elbow flexors were measured pre- and post-training. Blood flow restriction resulted in fewer repetitions and lower muscle tissue oxygenation at the end of exercise than FBF, while the muscle activity increased similarly to repetition failure. Blood flow restriction also resulted in a smaller post-training Rmax, which was strongly correlated with the total exercise volume over the 6 week period. Despite the smaller exercise volume, BFR resulted in similar improvements in half-time, muscle strength and thickness compared with FBF. These results suggest that the application of BFR can attenuate muscle endurance adaptations to low-load resistance training by decreasing the number of repetitions during exercise, both acutely and chronically.

Principles, developments, and applications of spatially resolved spectroscopy in agriculture: a review

Agriculture is the primary source of human survival, which provides the most basic living and survival conditions for human beings. As living standards continue to improve, people are also paying more attention to the quality and safety of agricultural products. Therefore, the detection of agricultural product quality is very necessary. In the past decades, the spectroscopy technique has been widely used because of its excellent results in agricultural quality detection. However, traditional spectral inspection methods cannot accurately describe the internal information of agricultural products. With the continuous research and development of optical properties, it has been found that the internal quality of an object can be better reflected by separating the properties of light, such as its absorption and scattering properties. In recent years, spatially resolved spectroscopy has been increasingly used in the field of agricultural product inspection due to its simple compositional structure, low-value cost, ease of operation, efficient detection speed, and outstanding ability to obtain information about agricultural products at different depths. It can also separate optical properties based on the transmission equation of optics, which allows for more accurate detection of the internal quality of agricultural products. This review focuses on the principles of spatially resolved spectroscopy, detection equipment, analytical methods, and specific applications in agricultural quality detection. Additionally, the optical properties methods and direct analysis methods of spatially resolved spectroscopy analysis methods are also reported in this paper.

Wearable Prophylaxis Tool for AI-Driven Identification of Early Warning Patterns of Pressure Ulcers

As today's society ages, age-related diseases become more frequent. One very common but yet preventable disease is the development of pressure ulcers (PUs). PUs can occur if tissue is exposed to a long-lasting pressure load, e.g., lying on tissue without turning. The cure of PUs requires intensive care, especially for the elderly or people with preexisting conditions whose tissue needs longer healing times. The consequences are heavy suffering for the patient and extreme costs for the health care system. To avoid these consequences, our objective is to develop a pressure ulcer prophylaxis device. For that, we built a new sensor system able to monitor the pressure load and tissue vital signs in immediate local proximity at patient's predilection sites. In the clinical study, we found several indicators showing correlations between tissue perfusion and the risk of PU development, including strongly reduced SpO2 levels in body tissue prior to a diagnosed PU. Finally, we propose a prophylaxis system that allows for the prediction of PU developments in early stages before they become visible. This work is the first step in generating an effective system to warn patients or caregivers about developing PUs and taking appropriate preventative measures. Widespread application could reduce patient suffering and lead to substantial cost savings.

BASS: Safe Deep Tissue Optical Sensing for Wearable Embedded Systems

In wearable optical sensing applications whose target tissue is not superficial, such as deep tissue oximetry, the task of embedded system design has to strike a balance between two competing factors. On one hand, the sensing task is assisted by increasing the radiated energy into the body, which in turn, improves the signal-to-noise ratio (SNR) of the deep tissue at the sensor. On the other hand, patient safety consideration imposes a constraint on the amount of radiated energy into the body. In this paper, we study the trade-offs between the two factors by exploring the design space of the light source activation pulse. Furthermore, we propose BASS, an algorithm that leverages the activation pulse design space exploration, which further optimizes deep tissue SNR via spectral averaging, while ensuring the radiated energy into the body meets a safe upper bound. The effectiveness of the proposed technique is demonstrated via analytical derivations, simulations, and in vivo measurements in both pregnant sheep models and human subjects.

Investigation of oxygen saturation in regions of skin by near infrared spectroscopy

BACKGROUND

Oxygen is essential for life, and investigation of the skin's oxygen environment and identification of its effects on the skin may lead to the discovery of new antiaging targets. To understand individual skin differences and age-related changes, we developed a noninvasive method using near infrared spectroscopy (NIRS) to measure the regional saturation of oxygen (rSO₂ ) of human skin.

MATERIALS AND METHODS

To construct an NIRS sensor probe specialized for skin measurement, the distance between the sensor transmitter and receiver was optimized based on data for the thickness of the facial skin to the subcutaneous fat layer. To analyze the relationship between skin oxygen saturation and body oxygen saturation, rSO₂ was measured by NIRS, oxygen saturation of peripheral artery (SpO₂ ) was measured by pulse oximeter, and physical conditions were considered, such as body mass index (BMI) and muscle mass, in Japanese women (age 20s-60s).

RESULTS

Both skin rSO₂ and SpO₂ varied among individuals and decreased with age. Only SpO₂ showed a relationship with BMI and muscle mass, whereas rSO₂ showed no relationship with these physical conditions. No relationship between rSO2 and SpO₂ was observed.

CONCLUSION

Individual and age-related differences in skin by rSO₂ values were found by NIRS optimized for local skin; however, the factors affecting rSO₂ differed from those affecting SpO₂ , and further study is needed.

The Patency of Tibial/Peroneal Arteries Affects the Increment of Regional Tissue Saturation of Oxygen in Each Angiosome after Superficial Femoral Artery Revascularization

Objective: The angiosome model is a controversial concept in the revascularization of patients with chronic limb-threatening ischemia (CLTI). The aim of this study was to demonstrate the importance of patency of the tibial/peroneal arteries for regional tissue oxygenation in each angiosome during endovascular therapy (EVT) of the superficial femoral artery (SFA).

Materials and Methods: We devised a novel near-infrared spectroscopy oximeter, “TOE-20,” for real-time monitoring of regional tissue oxygen saturation (rSO₂). Using TOE-20, we prospectively assessed rSO₂ at each angiosome in 23 CLTI patients who underwent successful revascularization of the SFA. During EVT, three sensor probes were placed at the dorsal foot, plantar foot, and outer ankle for rSO₂ monitoring.

Results: At the end of EVT, rSO₂ at all angiosomes was significantly elevated by SFA revascularization. The change in rSO₂ in each angiosome was larger in patients with patent relevant arteries than in those with occluded relevant arteries (i.e., anterior tibial artery patency, posterior tibial artery patency, and peroneal artery patency).

Conclusion: The patency of the tibial/peroneal arteries is important for regional tissue oxygenation in EVT. Using TOE-20 and rSO₂-based revascularization, it may possible to anticipate whether an ischemic ulcer will heal or not.