Gender-Related Effect in Oxygenation Dynamics by Using Far-Infrared Intervention with Near-Infrared Spectroscopy Measurement: A Gender Differences Controlled Trial

Incremental shuttle walking test for calf muscle oxygenation assessment in peripheral arterial disease: a cross-sectional study

People with peripheral arterial disease (PAD) and intermittent claudication (IC) experience impaired walking due to an imbalance between muscle oxygen supply and demand during exercise. Studies with near-infrared spectroscopy (NIRS) during treadmill tests reveal notable tissue deoxygenation with slow recovery. This cross-sectional study aimed to compare behavior of calf muscle oxygenation during the incremental shuttle walking test (ISWT) with a continuous treadmill test (3.2 km/h, 10% incline) and to correlate NIRS results between tests in PAD patients. Sixty individuals with IC, 37 men (61.7%), mean age 66.25 ± 10.35 years participated in the study. Both tests were performed on the same day with a 30-minute rest, in randomized order. NIRS-derived calf muscle tissue oxygenation variables were measured at rest and during exercise. Typical PAD tissue oxygenation patterns were observed in both tests, with significant differences (p < 0.05) in oxygenation values during exercise for the variables delta of tissue oxygen saturation (ΔStO2) and reoxygenation rates. All tissue oxygenation variables analyzed, except reoxygenation rate, showed a significant and directly proportional correlation between the two tests. These results suggest that NIRS during ISWT could be a viable method for assessing tissue oxygenation in PAD.

Effects of occlusion pressure on hemodynamic responses recorded by near-infrared spectroscopy across two visits

Ischemic Preconditioning (IPC) has emerged as a promising approach to mitigate the impact of hypoxia on physiological functions. However, the heterogeneity of occlusion pressures for inducing arterial occlusion has led to inconsistent hemodynamic outcomes across studies. This study aims to evaluate the peripheral hemodynamic responses to partial and total blood-flow occlusions on the left arm at rest, using absolute or individualized pressures, on two occasions. Thirty-five young males volunteered to participate in this study. IPC procedure (3 × 7-min) was performed on the left upper arm with cuff pressures at 50 mmHg (G1), 50 mmHg over the systolic blood pressure (SBP + 50 mmHg) (G2) or 250 mmHg (G3). NIRS-derived parameters were assessed for each occlusion and reperfusion phase in the brachioradialis. Results showed a significantly lower magnitude of deoxygenation (TSIAUC) for G1 compared to G2 (-1959.2 ± 1417.4 vs. -10908.1 ± 1607.5, P < 0.001) and G3 -1959.2 ± 1417.4 vs. -11079.3 ± 1828.1, P < 0.001), without differences between G2 and G3. However, G3 showed a significantly faster reoxygenation only for tissue saturation index (TSIslope) compared to G2 (1.3 ± 0.1 vs. 1.0 ± 0.2, P = 0.010), but without differences in the speed of recovery of deoxyhemoglobin [(HHb) slope], or in the magnitude of post-occlusive hyperemia (PORH). Besides TSI reoxygenation speed, G2 and G3 elicit comparable resting hemodynamic responses measured by NIRS. Thus, this study highlights the practicality and effectiveness of using relative occlusion pressures based on systolic blood pressure (SBP) rather than relying on excessively high absolute pressures.

Far-infrared radiation and its therapeutic parameters: A superior alternative for future regenerative medicine?

In future regenerative medicine, far-infrared radiation (FIR) may be an essential component of optical therapy. Many studies have confirmed or validated the efficacy and safety of FIR in various diseases, benefiting from new insights into FIR mechanisms and the excellent performance of many applications. However, the lack of consensus on the biological effects and therapeutic parameters of FIR limits its practical applications in the clinic. In this review, the definition, characteristics, and underlying principles of the FIR are systematically illustrated. We outline the therapeutic parameters of FIR, including the wavelength range, power density, irradiation time, and distance. In addition, the biological effects, potential molecular mechanisms, and preclinical and clinical applications of FIR are discussed. Furthermore, the future development and applications of FIR are described in this review. By applying optimal therapeutic parameters, FIR can influence various cells, animal models, and patients, eliciting diverse underlying mechanisms and offering therapeutic potential for many diseases. FIR could represent a superior alternative with broad prospects for application in future regenerative medicine.

Gender-Related Difference in Skin Oxygenation in Young Patients with Uncomplicated Type 1 Diabetes

Gender, through genetic, epigenetic and hormonal regulation, is an important modifier of the physiological mechanisms and clinical course of diseases. In diabetes mellitus, there are gender differences in incidence, prevalence, morbidity, and mortality. This disease also has an impact on the microvascular function. Therefore, this cross-sectional study was designed to investigate how gender affects the cutaneous microcirculation. We hypothesized that gender should be an important factor in the interpretation of capillaroscopy and transcutaneous oxygen saturation results. The study group consisted of 42 boys and 55 girls, uncomplicated diabetic pediatric patients. Females (F) and males (M) did not differ in terms of age, age at onset of diabetes, or diabetes duration. Furthermore, they did not differ in metabolic parameters. The comparison showed that group F had lower BP, higher pulse, and higher HR than group M. Group F had significantly lower creatinine and hemoglobin levels than group M. In children and adolescents with type 1 diabetes without complications, there was a gender difference in microcirculatory parameters. The resting transcutaneous partial pressure of oxygen was significantly higher in females than in males. However, there were no gender-related differences in basal capillaroscopic parameters or vascular reactivity during the PORH test. Our results indicate that studies investigating the structure and function of the microcirculation should consider the role of gender in addition to known cofactors such as puberty, body mass index, physical activity, and cigarette smoking.

A Phase 1 randomized, open-label clinical trial to evaluate the effect of a far-infrared emitting patch on local skin perfusion, microcirculation and oxygenation

Far-infrared radiation (FIR) has been investigated for reduction of pain and improvement of dermal blood flow. The FIRTECH patch is a medical device designed to re-emit FIR radiated by the body. This phase 1 study was conducted to evaluate the local effects of the FIRTECH patch on local skin perfusion, microcirculation and oxygenation. This prospective, randomized, open-label, parallel designed study admitted 20 healthy participants to a medical research facility for treatment for 31 h on three anatomical locations. During treatment, imaging assessments consisting of laser speckle contrast imaging, near-infrared spectroscopy, side-stream dark-field microscopy, multispectral imaging and thermography were conducted regularly on patch-treated skin and contralateral non-treated skin. The primary endpoint was baseline perfusion increase during treatment on the upper back. Secondary endpoints included change in baseline perfusion, oxygen consumption and temperature of treated versus untreated areas. The primary endpoint was not statistically significantly different between treated and non-treated areas. The secondary endpoints baseline perfusion on the forearm (least square means [LSMs] difference 2.63 PU, 95% CI: 0.97, 4.28), oxygen consumption (LSMs difference: 0.42 arbitrary units [AUs], 95% CI: 0.04, 0.81) and skin temperature (LSMs difference 0.35°C, 95% CI: 0.16, 0.6) were statistically significantly higher in treated areas. Adverse events observed during the study were mild and transient. The vascular response to the FIRTECH patch was short-lived suggesting a non-thermal vasodilatory effect of the patch. The FIRTECH patch was well tolerated, with mild and transient adverse events observed during the study. These results support the therapeutic potential of FIR in future investigations.

Implementation of a six-around-one optical probe based on diffuse light spectroscopy for study of cerebral properties in a murine mouse model of autism spectrum disorder

Light reflectance spectroscopy (LRS) is a multispectral technique, sensitive to the absorption and scattering properties of biological molecules in tissues. It is used as a noninvasive tool to extract quantitative physiological information from human tissues and organs. A near-infrared LRS based on a single optical probe was used to monitor changes in optical and hemodynamic parameters in a mouse model of autism. A murine model of autism induced by developmental exposure to valproic acid (VPA) was used. Since autism could be attributed to neuroanatomical changes, we hypothesize that these changes can be detected using the LRS because spectral properties depend on both molecular composition and structural changes. The fiber-optic probe in the setup consisted of seven small optical fibers: six fibers for illumination placed in a circular manner around a central single collection fiber. Overall, measurements demonstrate changes in diffused reflectance spectra, cerebral optical tissue properties (absorption and scattering), and chromophore levels. Furthermore, we were able to identify differences between male and female groups. Finally, the effectiveness of S-Adenosylmethionine as a drug therapy was studied and found to improve the hemodynamic outcome. For the first time, to the best of our knowledge, the LRS is utilized to study variations in brain parameters in the VPA autism model mice through an intact scalp.

Task and sex differences in muscle oxygenation during handgrip fatigue development

The purpose of this study was to examine task and sex differences in forearm muscle oxygenation, measured using near infrared spectroscopy, during sustained submaximal handgrip exercises. Forty-eight adults (50% males) performed fatiguing handgrip exercises at 20, 40, 60 and 80% of their maximum handgrip strength. While males and females exhibited similar levels of relative fatigability, forearm oxygenation was found to be task (i.e. contraction intensity and phase of fatigue development) and sex dependent. Higher contraction intensities were associated with greater desaturation over time. Compared to females, males exhibited greater desaturation as fatigue progressed and this was augmented at higher contraction intensities. These may be likely affected by sex differences in muscle mass, morphology and strength differences during exercises at relative intensities. Future work that explores sex differences in muscle oxygenation during absolute force intensities are needed, which may have implications for muscle fatigue development and potential fatigue mitigation strategies. Practitioner Summary: Muscle oxygenation impacts fatigue development that can in turn affect worker health and productivity. Males exhibit greater forearm desaturation than females at higher relative work intensities, despite similar fatigue levels. Females may be predisposed to greater muscle delivery and oxygenation challenges that can increase their fatigability during work at absolute load levels.

Soft tissue micro-circulation in the healthy hindfoot: a cross-sectional study with focus on lateral surgical approaches to the calcaneus

PURPOSE

Open reduction and internal fixation (ORIF) using an extended lateral approach combined with plate osteosynthesis represents the current gold standard in calcaneal fracture treatment, but it is associated with a wound complication rate of up to 30%. Literature suggests that micro-circulation is one of the key factors for sufficient wound healing. The aim of this study was to evaluate soft tissue micro-circulation of the hindfoot in healthy volunteers to determine influencing factors and to identify hypoxic or hypoperfused areas in non-trauma situations, with special attention to surgical approaches.

METHODS

Micro-circulation of the lateral hindfoot of 125 participants was non-invasively measured at 2 and 8 mm depths, utilizing a Micro-Lightguide O2C® spectrophotometer. Blood flow (BF [AU]) and oxygen saturation (SO2 [%]) of ten measurement points (MPs) were documented. Demographic factors (age, gender, body mass index [BMI], systolic/diastolic blood pressure, smoking, and pack-years) and regional differences with special regard to surgical approaches (extended lateral approach, Palmer approach, Ollier approach, and a self-modified extended lateral approach) were analyzed.

RESULTS

The SO2 assessments at 2- and 8-mm depths revealed higher values in males (p = 0.043; p = 0.025). There was a correlation between higher age and lower 2 mm BF (p = 0.044). Smoking history and number of pack-years did not predict micro-circulation. BF at the 2 mm depth was highest in the regions of Palmer and Ollier approach (p < 0.001). The MP at the distal calcaneal tuberosity showed significantly higher values regarding all parameters (SO2 (2 mm), p < 0.001; SO2 (8 mm), p = 0.001; BF (2 mm), p < 0.001; BF (8 mm), p < 0.001), compared to the surrounding area.

CONCLUSIONS

In non-trauma situations, young males were associated with better micro-circulatory supply of the lateral hindfoot. There was a trend for higher blood flow in regions of the Palmer and Ollier approach. The distal calcaneal tuberosity was clearly superior in all micro-circulatory parameters when compared to the surrounding area.

Soft tissue microcirculation around the healthy Achilles tendon: a cross-sectional study focusing on the Achilles tendon and dorsal surgical approaches to the hindfoot

Background

Dorsal approaches to the hindfoot are frequently used. Furthermore, the vascular supply is discussed as a possible cause for ruptures and degeneration of the Achilles tendon. The aim of this study was to evaluate the microperfusion of three possible posterior approaches to the hindfoot and different areas of the Achilles tendon.

Methods

In 111 subjects, a laser Doppler/white light spectroscopy was used to measure microperfusion in terms of blood flow (Flow) and capillary venous oxygen saturation (SO2) in the hindfoot and Achilles tendon. Measurements were performed at two measurement points (MP, proximal and distal) of three dorsal approaches (medial, lateral and central) and inside the Achilles tendon.

Results

Microperfusion differed partially between the surgical approaches. The medial and the lateral approaches were significantly superior to the central approach with regard to Flow in both MP (p <  0.001), while SO2 was significantly higher at the proximal measurement point (MP 1; p <  0.001). In this area, the lateral approach was significantly superior to the medial approach regarding Flow (MP 1; p = 0.012).

The Achilles tendon exhibited a significantly reduced microperfusion 5 cm proximal to the calcaneal tubercle (SO2 p = 0.001; Flow p = 0.048). Demographic factors, such as body mass index and age, had different effects. Microcirculation was partially superior in men and negatively affected by smoking.

Conclusions

Soft tissue microcirculation on the lateral and medial side of the healthy Achilles tendon was better than centrally on the tendon. Proximally, the lateral approach was better than the medial approach. These circumstances could provide advantages regarding the surgical approach. The Achilles tendon exhibited significantly reduced microperfusion at the typical side of degeneration and rupture. This circumstance could be a possible cause of degenerative processes.

Oxygenation dynamics of sepsis patients undergoing far-infrared intervention based on near-infrared spectroscopy

Near-infrared spectroscopy (NIRS; continuous wave type) is a noninvasive tool for detecting the relative change of oxyhemoglobin and deoxyhemoglobin. To make this change, intervention methods must be applied. This study determined the hemodynamics of 44 healthy participants and 35 patients with sepsis during exposure to FIR as a novel physical intervention approach. Local microcirculation of their brachioradialis was monitored during exposure and recovery through NIRS. The variations in blood flow and microvascular reaction were determined by conducting paired and unpaired t tests. The oxyhemoglobin levels of the healthy participants increased continuously, even during recovery. In contrast to expextations, the oxyhemoglobin levels of the patients plateaued after only 5 min of FIR illumination. The proposed method has potential applications for ensuring efficient treatment and facilitating doctors in diagnosing the functions of vessels in intensive care units. Mapping diagrams of HbO₂ in healthy males and males with sepsis illustrated unique scenarios during the process.