Tissue Oxygen Saturation Research Articles

Biomarkers in the Severity of Necrotizing Enterocolitis in Preterm Infants: A Pilot Study.

The occurrence of necrotizing enterocolitis (NEC) is a common and severe disease of the digestive system in neonates. This study aims to assess the value of the intestinal tissue oxygen saturation (rintSO2) combined with the levels of procalcitonin (PCT) and mean platelet volume (MPV) in predicting the severity of NEC in preterm infants. This experiment was a retrospective cohort study conducted in the Department of Pediatrics, Hongqi Hospital Affiliated to Mudanjiang Medical University between January 2017 and July 2022. Premature neonates with NEC were enrolled and divided into mild-moderate NEC group and severe NEC group according to Bell's stage. The general information data, rintSO2 and blood parameters such as the white blood cell (WBC) count, platelet count (PLT), PCT, MPV, red blood cell distribution width (RDW), hemoglobin (Hb), C-reactive protein (CRP) were compared between the two groups. A total of 122 patients were enrolled, including 79 mild-moderate NEC and 43 severe NEC. The rintSO2 was lower in severe group than in mild-moderate group (P = 0.042), the PCT and MPV were both higher in severe group than in mild-moderate group (P = 0.048, P = 0.049). The results of logistic regression suggested that the rintSO2 (OR = 1.491, P = 0.003), PCT (OR = 3.071, P = 0.001) and MPV (OR = 4.027, P = 0.015) were independent predictive factors for severity of NEC. The area under the curve (AUC) of the rintSO2 combined with PCT and MPV showed good diagnostic ability in the severity of NEC. The rintSO2 combined with PCT and MPV may be considered as the early biomarkers in the severity of NEC and could help us to diagnose the case early with early treatment with better prognosis.

Intraoperative Near-infrared Spectroscopy Can Predict Skin Flap Necrosis.

The study aimed to validate the previously identified capacity of near-infrared spectroscopy (NIRS) to detect clinically relevant differences in tissue perfusion intraoperatively. Consecutive patients undergoing oncologic resection requiring flap reconstruction were analyzed. Clinicians were blinded to tissue oxygen saturation (StO2) measurements taken intraoperatively. Measurements were taken at (1) control areas not affected by the procedure, (2) areas at risk of necrosis based on distal location, and (3) areas of skin flap necrosis (SFN) identified during the follow-up period. Mean StO2 values were compared using a single-sample t test and analysis of variance (ANOVA) to determine differences in oxygenation. There were 102 patients included from April 2018 to May 2019. Reconstruction was undertaken following resection for breast cancer (46), melanoma (35), sarcoma (9), and other cutaneous malignancies (12). Breast reconstruction involved 38 alloplastic reconstructions and eight autologous free flaps. Other skin flap reconstruction involved 42 local/regional skin flaps, 13 pedicled flaps, and one free flap. Eighteen patients (17.6%) developed SFN. Mean intraoperative StO2 measurements for control areas, areas at risk, and areas of SFN were 74.8%, 70.9%, and 54.3%, respectively. StO2 values equal to or less than 60% were highly specific (96%) for SFN, whereas StO2 values above 85% were highly sensitive (96%) to rule out SFN. These results further support the use of NIRS to objectively assess variations in skin flap oxygenation and tissue perfusion that are correlated with the development of postoperative SFN.

Reference Ranges for Regional Cerebral Oxygen Saturation with Masimo O3 after Birth and Differences with Other Devices.

Cerebral oximetry using near-infrared spectroscopy (NIRS) is a noninvasive optical technology widely used in neonatology. The present study aimed to define reference ranges for cerebral tissue oxygen saturation (crSO2) with a new four-wavelength NIRS device, Masimo O3 oximeter, during immediate transition after birth and compare values with those obtained previously with NIRO 200NX®. This was a prospective observational study using Masimo O3 device to measure crSO2 and regional cerebral fractional tissue oxygen extraction (cFTOE) in healthy term newborns delivered by primary cesarean section, during the 15 minutes after cord clamping. The neonates who required any medical support were excluded. The NIRS sensor was placed on the right forehead. Peripheral oxygen saturation and heart rate were continuously measured by pulse oximetry. Previous studies which established centiles for crSO2 with NIRO 200NX were used for comparison. A total of 44 newborns were included. The median crSO2 and cFTOE (interquartile range) at 2, 5, and 7 minutes was 54% (49-54), 71% (64-86), and 79% (73-84) and 0,25 (0,18-0,33), 0,19 (0,15-0,23), and 0,16 (0,12-0,21), respectively, with no further changes afterwards. The crSO2 measurements were significantly higher with Masimo O3 compared with NIRO-200NX. The present observational study presented reference ranges for crSO2 and cFTOE measured with Masimo O3 oximeter during the immediate neonatal transition. Values obtained with O3 were higher than those obtained with other oximeters. For this reason, crSO2 is device-specific so there must be known reference values for each oximeter to define therapeutic interventions based on crSO2 and assess cerebral oxygenation in clinical studies. · Masimo O3 uses four wavelengths to measure regional oxygen saturation value.. · O3 values of crSO2 and cFTOE differ with other neonatal oximeters at birth.. · Knowledge of reference range of O3 at birth is essential to guide resuscitation..

Association of tissue oxygen saturation levels with skeletal muscle injury in the critically ill.

This study aimed to investigate the association between the level of tissue oxygen saturation (StO2) and quadriceps/skeletal muscle dysfunction, measured using the Medical Research Council (MRC) scale and ultrasonography, in critically ill patients. Thirty-four patients hospitalized at the Critical Care Medicine Center of Kindai University Hospital, between January 2022 and March 2023, were enrolled in this study. The StO2 of the quadriceps muscle was measured via near-infrared spectroscopy. Muscle atrophy was measured by the thickness, cross-sectional area (CSA), and echo intensity of the rectus femoris (RF). These values were evaluated every alternate day until 13days after admission or until discharge, whichever occurred first. Muscle weakness was assessed using the sum score of the MRC scale (MRC-SS), with the patient sitting at bedside. The mean age of the patients was 67.3 ± 15.3years, and 20 (59%) were men. Seven patients (21%) were admitted for trauma, and 27 (79%) were admitted for medical emergencies or others. The mean score for the MRC-SS was 51.0 ± 7.9 points. RF thickness and CSA significantly decreased after day 7 (p < 0.05). There were no significant changes in StO2 levels during hospitalization. However, there were positive correlations between the nadir StO2 during hospitalization and MRC-SS, and changes in RF thickness and CSA at discharge (r = 0.41, p = 0.03; r = 0.37, p = 0.03; and r = 0.35, p = 0.05, respectively). StO2 in the quadriceps muscle may be useful for predicting muscle atrophy and dysfunction in patients with critical illnesses.

The relationship between trajectories of renal oxygen saturation and acute kidney injury: a prospective cohort study with a secondary analysis

BackgroundAcute kidney injury (AKI) is a major postoperative consequence, affecting prognosis of older patients. Effective prediction or intervention to predict or prevent the incidence of AKI is currently unavailable.AimsDynamic changes of renal tissue oxygen saturation (RSO2) during surgery process are understudied and we intended to explore the distinct trajectories and associations with postoperative AKI.MethodsThis was a secondary analysis including data for older patients who underwent open hepatectomy surgery with informed consent. Latent class mixed models (LCMM) method was conducted to generate trajectories of intraoperative renal tissue RSO2 through different time points. The primary outcome was postoperative 7-day AKI. The univariate and multivariate regression analysis were performed to identify the relationship between distinct trajectories of renal tissue RSO2 and the risk of AKI. Meanwhile, the prediction efficacy of renal tissue RSO2 at different time points was compared to find potential intervention timing.ResultsPostoperative AKI occurred in 14 (15.2%) of 92 patients. There are two distinct renal tissue RSO2 trajectories, with 44.6% generating "high-downwards" trajectory and 55.4% generating "consistently-high" trajectory. Patients with "high-downwards" trajectory had significantly higher risk of postoperative AKI than another group (Unadjusted OR [Odds Ratio] = 3.790, 95% CI [Confidence Interval]: 1.091–13.164, p = 0.036; Adjusted OR = 3.973, 95% CI 1.020–15.478, p = 0.047, respectively). Predictive performance was 71.4% sensitivity and 60.3% specificity for "high-downwards" trajectory of renal tissue RSO2 to identify AKI. Furthermore, the renal tissue RSO2 exhibited the lowest level and the best results in terms of the sensitivity during the hepatic occlusion period, may be considered as a "time of concern".ConclusionsOlder patients undergoing hepatectomy may show high-downwards trajectory of renal tissue RSO2, indicating a higher risk of AKI, and the lowest level was identified during the hepatic occlusion period. These findings may help to provide potential candidates for future early recognition of deterioration of kidney function and guide interventions.

Value of brain tissue oxygen saturation in neonatal respiratory distress syndrome: a clinical study.

Neonatal respiratory distress syndrome (NRDS) is one of the major causes of pre-term mortality and morbidity among very-low-birth-weight infants (VLBWI) in low- and middle-income countries (LMIC). Some of the neonates pass away despite admission and care in intensive care units (ICUs). The present clinical trial seeks the application value of elevating oxygen saturation in the brain cells of pre-term neonates born with NRDS. Near-infrared spectroscopy (NIRS) was used to monitor the neonates' microscopic cerebral oxygenation levels do determine hemoglobin concentration in brain tissues, whereas the pulse oximetry was used to measure oxygenation levels among the patients. In statistical analyses, the Analysis of Variance (ANOVA), and descriptive statistics was deployed in the Jupyter Notebook environment using Python language. High saturation of oxygen in the brain tissues result in important biological and physiological processes, including enhanced oxygen supply to cells, reduced severity of NRDS, and balancing oxygen demand and supply. The correlations of oxygen saturation with systemic saturation of oxygen, the saturation of oxygen in brain tissues, the association between brain-specific and systemic saturation, and the impact of these outcomes on clinical practices were deliberated. Also, the pH gas values, the saturation of oxygen in neonates' brain tissues, metabolic acidosis, the effect of acid-base balance and cerebral oxygen supply, and the oxygenation of brain tissues and the pH values emerged as important variables of oxygenation of brain tissues in pre-term neonates. Oxygen saturation in brain cells influence vital physiological and biological processes. Balancing acid-base saturation or levels is needed despite the challenging achievement. Oxygenation of brain tissues improve the brain's overall functioning.

In vivo visualization of burn depth in skin tissue of rats using hemoglobin parameters estimated by diffuse reflectance spectral imaging.

Burn injuries represent a global public health problem that kills an estimated 180,000 people annually. Non-fatal burns result in prolonged hospitalization, disfigurement, and disability. The most common, convenient, and widely used method for assessing burn depth is physical or visual examination, but the accuracy of this method is reportedly poor (60% to 75%). Rapid, correct assessment of burn depth is very important for the optimal management and treatment of burn patients. New methods of burn depth assessment that are inexpensive, simple, rapid, non-contact, and non-invasive are therefore needed. The aim of this study was to propose an approach to visualize the spatial distribution of burn depth using hemoglobin parameters estimated from spectral diffuse reflectance imaging and to demonstrate the feasibility of the proposed approach for differentiating burn depth in a rat model of scald burn injury. The new approach to creating a spatial map of burn depth was based on canonical discriminant analysis (CDA) of total hemoglobin concentration, tissue oxygen saturation, and methemoglobin saturation as estimated from spectral diffuse reflectance images. Burns of three different degrees of severity were created in rat dorsal skin by 10-s exposure to water maintained at 70°C, 78°C, and 98°C, respectively. Spectral images for dorsal regions were acquired under anesthesia immediately after burn injury and at 24h, 48h, and 72h after injury. Most areas of images in the group with skin exposed to 70°C water and 98°C water were classified as 70°C burn and 98°C burn, respectively. In contrast, no significant difference between areas classified as 78°C burn and 98°C burn from 24h to 72h was evident in the group with skin exposed to 78°C water, suggesting that burn depth was heterogeneous. The proposed approach combining diffuse reflectance spectral imaging and CDA appears promising for differentiating 70°C burns from 78°C burns and 98°C burns, and 98°C burns from 70°C burns and 78°C burns at 24 to 72h after burn injury in a rat model of scald burn injury.

Modeling cerebrovascular responses to assess the impact of the collateral circulation following middle cerebral artery occlusion.

An improved understanding of the role of the leptomeningeal collateral circulation in blood flow compensation following middle cerebral artery (MCA) occlusion can contribute to more effective treatment development for ischemic stroke. The present study introduces a model of the cerebral circulation to predict cerebral blood flow and tissue oxygenation following MCA occlusion. The model incorporates flow regulation mechanisms based on changes in pressure, shear stress, and metabolic demand. Oxygen saturation in cerebral vessels and tissue is calculated using a Krogh cylinder model. The model is used to assess the effects of changes in oxygen demand and arterial pressure on cerebral blood flow and oxygenation after MCA occlusion. An increase from five to 11 leptomeningeal collateral vessels was shown to increase the oxygen saturation in the region distal to the occlusion by nearly 100%. Post-occlusion, the model also predicted a loss of autoregulation and a decrease in flow to the ischemic territory as oxygen demand was increased; these results were consistent with data from experiments that induced cerebral ischemia. This study highlights the importance of leptomeningeal collaterals following MCA occlusion and reinforces the idea that lower oxygen demand and higher arterial pressure improve conditions of flow and oxygenation.

Comparison of skeletal muscle oxidative function in young, middle-aged, and older males and females with similar physical activity levels.

Optimal skeletal muscle oxidative function (microvascular reactivity and mitochondrial capacity) is an integral part of healthy aging and is related to physical function and quality of life. We aimed to extend upon the understanding of skeletal muscle oxidative function with healthy aging in males and females across the adult life span. Younger (N = 22; 11 males), middle-aged (N = 19; 10 males), and older (N = 21; 10 males) adults completed this study. Time spent in moderate and vigorous physical activity was self-reported and similar among groups. Near-infrared spectroscopy was used to investigate skeletal muscle microvascular reperfusion [oxyhemoglobin-myoglobin (O2Hb+Mb) half-time to peak hyperemia (T½)], mitochondrial capacity [muscle oxygen consumption (mV̇o2) recovery rate constant], and walking tissue oxygen saturation ([Formula: see text]) of the tibialis anterior (TA) muscle at seven incremental walking speeds. Mitochondrial capacity was not significantly different across groups (P = 0.07). Younger adults exhibited significantly slower T½ compared with older adults (P = 0.006) and middle-aged adults (P = 0.025). There were no observed sex differences for mitochondrial capacity (P = 0.442) or T½ (P = 0.402). Older adults exhibited significantly lower [Formula: see text] across all walking speeds compared with younger adults (P = 0.003). Mitochondrial capacity and microvascular reperfusion are maintained in middle and older age, with no sex differences in either outcome. However, in older adults whole body functional movement, such as walking, may place an additional demand on the TA as a compensatory response to lower functional reserve not evident in distinct measures of mitochondrial capacity and microvascular reperfusion.NEW & NOTEWORTHY Compared with younger adults, mitochondrial capacity and microvascular reperfusion of the tibialis anterior (TA) muscle are well maintained in similarly physically active middle-aged and older adults, with no sex differences observed in either outcome. However, greater tissue oxygen utilization in older adults during walking highlights how whole body functional movement may place an additional demand on the TA that reveals a potential compensatory response to lower functional reserve not evident in distinct measures of mitochondrial capacity and microvascular reperfusion.

Evaluation of cerebral autoregulation of oxygen by NIRS method during postnatal transition period in term and late preterm newborns without resuscitation requirement.

Pulse oximetry is commonly used to monitor arterial oxygen saturation and heart rate during the transition period and reference intervals have been determined. However, the effect of the change in arterial oxygen saturation on tissue oxygenation does not seem to be the same. So, a non-invasive method for monitoring cerebral or regional tissue oxygenation will be potentially useful for vulnerable infants. This study aims to evaluate the effectiveness of cerebral autoregulation in the first 10 min after delivery in term and late preterm newborns without resuscitation requirement. Cerebral tissue oxygen saturation was measured in the first 10 min after birth with near-infrared spectroscopy (NIRS) from the left forehead. Peripheral oxygen saturation was measured with pulse oximetry from the right hand and cerebral fractional tissue oxygen extraction was calculated. Nineteen late preterms and 20 term infants were included in the study. There was no statistically significant difference between median cerebral tissue oxygen saturation and cerebral fractional tissue oxygen extraction values of late preterm and term infants (p < 0.001). There was a strong inverse relationship between cerebral tissue oxygen saturation and cerebral fractional tissue oxygen extraction (p < 0.001). In late preterm infants similar to term infants, arterial oxygen saturation and cerebral tissue oxygen saturation increased with time, but inverse reduction of cerebral fractional tissue oxygen extraction showed the presence of an active autoregulation in the brain. This can be interpreted as the ability of the brain to protect itself from hypoxia by regulating oxygen uptake during normal fetal-neonatal transition process. A larger scale multi-center randomized control trial is now needed to further inform practice.

Oxygen Saturation Increase in Ischemic Wound Tissues after Direct and Indirect Revascularization.

The primary approach for treating ischemic wounds is restoring oxygen supply to the ischemic region. While direct angiosomal revascularization is often associated with better post-operative wound healing and limb salvage, its superiority over non-angiosomal revascularization remains controversial. This study aimed to compare intraoperative tissue oxygen saturation changes in ischemic zones following either direct or indirect revascularization in below-the-knee arteries. This prospective observational study included patients undergoing direct and indirect below-the-knee endovascular revascularizations. Assignment to the groups was not randomized. Near-infrared spectroscopy was used to monitor rSO2 changes near the ischemic wounds intraoperatively. The changes were compared between the groups. 15 patients (50%) underwent direct angiosomal revascularization, while an equal number of patients underwent indirect revascularization. Overall, a statistically significant increase in regional oxygen saturation was observed after revascularization (p = 0.001). No statistically significant difference was found between the direct and indirect revascularization groups (p = 0.619). This study revealed a minor difference in the oxygen saturation increase between the angiosomal and non-angiosomal revascularization groups. Such a finding indicates that the clinical significance of angiosomal revascularization is negligible and might be concealed by confounding factors, such as the vessel diameter and outflow impact on the restenosis rate.

Measurements of Electrodermal Activity, Tissue Oxygen Saturation, and Visual Analog Scale for Different Cuff Pressures.

The quantification of comfort in binding parts, essential human-machine interfaces (HMI) for the functioning of rehabilitation robots, is necessary to reduce physical strain on the user despite great achievements in their structure and control. This study aims to investigate the physiological impacts of binding parts by measuring electrodermal activity (EDA) and tissue oxygen saturation (StO2). In Experiment 1, EDA was measured from 13 healthy subjects under three different pressure conditions (10, 20, and 30 kPa) for 1 min using a pneumatic cuff on the right thigh. In Experiment 2, EDA and StO2 were measured from 10 healthy subjects for 5 min. To analyze the correlation between EDA parameters and the decrease in StO2, a survey using the visual analog scale (VAS) was conducted to assess the level of discomfort at each pressure. The EDA signal was decomposed into phasic and tonic components, and the EDA parameters were extracted from these two components. RM ANOVA and a post hoc paired t-test were used to determine significant differences in parameters as the pressure increased. The results showed that EDA parameters and the decrease in StO2 significantly increased with the pressure increase. Among the extracted parameters, the decrease in StO2 and the mean SCL proved to be effective indicators. Such analysis outcomes would be highly beneficial for studies focusing on the comfort assessment of the binding parts of rehabilitation robots.

Development of a Three-Wavelength Brain Tissue Oxygen Monitoring System Based on Near Infrared Spectrum

In the past 20 years, near infrared spectrum technology has been widely used in human body monitoring due to its non-invasive and real-time characteristics. Oxygen, as the main metabolic substance of the human body, is consumed the most in brain tissue. In order to prevent complications caused by a decrease in brain tissue oxygen during treatment, the patient's brain tissue blood oxygen saturation needs to be monitored in real time. Currently, most of the clinically used non-invasive cerebral blood oxygen detection equipments use dual wavelengths. Other substances on the detection path will cause errors in the measurement results. Therefore, this article proposes a three-wavelength method based on the basic principle of non-invasive monitoring of cerebral blood oxygen using near-infrared spectrum. The brain tissue oxygen saturation monitoring method of detecting light sources was initially verified through the built system, laying the foundation for subsequent system engineering.

Multispectral near-infrared spectroscopy study evaluating the effect of razor design on shaving-induced erythema.

While shaving-induced erythema is a common inflammatory skin issue, there is a lack of quantitative information on how well a shaving product performs in this regard. In this study, multispectral near-infrared spectroscopy (NIRS) imaging was used to quantitatively and qualitatively measure the extent of shaving-induced erythema. The research compares a safety razor and a cartridge razor to evaluate their impact on skin irritation. Fifty-nine healthy male volunteers without pre-existing skin conditions were enrolled. Basic demographics were recorded, and participants' faces or necks were imaged before shaving. Shaving was conducted on the right side of the face/neck with the safety razor and on the left side of the face/neck using the 3-blade cartridge razor. Images were captured immediately after shaving, at 5 and 10 min post-shaving. Tissue oxygen saturation (StO2) measurements demonstrated that the safety razor induced significantly less erythema than the cartridge razor. Immediately after shaving, 40.3% of skin shaved with the safety razor had erythema compared to 57.6% for the cartridge razor. At 5 min post-shaving, 36.5% of skin shaved with the safety razor had erythema, compared to 53.8% of cartridge razor. Multispectral NIRS revealed significant differences in shaving-induced erythema between safety and cartridge razors. Safety razors demonstrated a lower incidence of erythema, suggesting a potential advantage for individuals prone to skin irritation. This study contributes valuable insights into skin irritation and highlights the potential of multispectral NIRS in dermatology research.

Assessment of microcirculatory alteration by a vascular occlusion test using near-infrared spectroscopy in pediatric cardiac surgery: effect of cardiopulmonary bypass

ABSTRACT Objectives Cardiopulmonary bypass cause microcirculatory alterations. Near infrared spectroscopic measurement of tissue oxygen saturation and vascular occlusion test are novel technologies for assessing the microcirculatory function of peripheral tissue specifically in patients undergoing cardiac surgery with cardiopulmonary bypass.Our study aimed to evaluate dynamic microcirculatory function using the vascular occlusion testing during cardiac surgery in pediatric patients. Methods 120 pediatric patients were scheduled. Children had continuous regional oxygen saturation monitoring using near infrared spectroscopy and vascular occlusion test. Vascular occlusion test was performed five times; before induction (T1), after induction (T2), then during cardiopulmonary bypass with full flow (T3), after the termination of CPB (T4) and after sternum closure (T5). Results Basal value was the lowest at T3 and this value was significantly different among measurements (p < 0,01).Values for maximum and minimum tissue oxygen saturation were the lowest at T3 (83,4 and 52,9%).The occlusion slope varied significantly among measurements (p < 0,01).Reperfusion slopes were significantly different among measurements (p < 0,01) with a further progressive decrease in reperfusion slope with duration of cardiopulmonary bypass. Conclusion Microcirculatory function can assessed using VOT with forearm Near-infrared spectroscopy derived variables during cardiopulmonary bypass in pediatric cardiac surgery. Noninvasive assessment of microcirculatory perfusion during cardiopulmonary bypass can further help evaluate and improve circulatory support techniques. Trial Registration The research Project was registered at ClinicalTrials.gov (NCT06191913)

Motion-resistant three-wavelength spatial frequency domain imaging system with ambient light suppression using an 8-tap CMOS image sensor.

We present a motion-resistant three-wavelength spatial frequency domain imaging (SFDI) system with ambient light suppression using an 8-tap complementary metal-oxide semiconductor (CMOS) image sensor (CIS) developed at Shizuoka University. The system addresses limitations in conventional SFDI systems, enabling reliable measurements in challenging imaging scenarios that are closer to real-world conditions. Our study demonstrates a three-wavelength SFDI system based on an 8-tap CIS. We demonstrate and evaluate the system's capability of mitigating motion artifacts and ambient light bias through tissue phantom reflectance experiments and in vivo volar forearm experiments. We incorporated the Hilbert transform to reduce the required number of projected patterns per wavelength from three to two per spatial frequency. The 8-tap image sensor has eight charge storage diodes per pixel; therefore, simultaneous image acquisition of eight images based on multi-exposure is possible. Taking advantage of this feature, the sensor simultaneously acquires images for planar illumination, sinusoidal pattern projection at three wavelengths, and ambient light. The ambient light bias is eliminated by subtracting the ambient light image from the others. Motion artifacts are suppressed by reducing the exposure and projection time for each pattern while maintaining sufficient signal levels by repeating the exposure. The system is compared to a conventional SFDI system in tissue phantom experiments and then in vivo measurements of human volar forearms. The 8-tap image sensor-based SFDI system achieved an acquisition rate of 9.4 frame sets per second, with three repeated exposures during each accumulation period. The diffuse reflectance maps of three different tissue phantoms using the conventional SFDI system and the 8-tap image sensor-based SFDI system showed good agreement except for high scattering phantoms. For the in vivo volar forearm measurements, our system successfully measured total hemoglobin concentration, tissue oxygen saturation, and reduced scattering coefficient maps of the subject during motion (16.5cm/s) and under ambient light (28.9lx), exhibiting fewer motion artifacts compared with the conventional SFDI. We demonstrated the potential for motion-resistant three-wavelength SFDI system with ambient light suppression using an 8-tap CIS.

Thermo-haemodynamic coupling during regional thigh heating: Insight into the importance of local thermosensitive mechanisms in blood circulation.

A positive relationship between local tissue temperature and perfusion exists, with isolated limb-segment hyperthermia stimulating hyperaemia in the heated region without affecting the adjacent, non-heated limb segment. However, whether partial-limb segment heating evokes a heightened tissue perfusion in the heated region without directly or reflexly affecting the non-heated tissues of the same limb segment remains unknown. This study investigated, in 11 healthy young adults, the lower limb temperature and haemodynamic responses to three levels of 1h upper-leg heating, none of which alter core temperature: (1) whole-thigh (WTH; water-perfused garment), (2) quadriceps (QH; water-perfused garment) and (3) partial-quadriceps (PQH; pulsed shortwave diathermy) heating. It was hypothesised that perfusion would only increase in the heated regions. WTH, QH and PQH increased local heated tissue temperature by 2.9±0.6, 2.0±0.7 and 2.9±1.3°C (P<0.0001), respectively, whilst remaining unchanged in the non-heated hamstrings and quadriceps tissues during QH and PQH. WTH induced a two-fold increase in common femoral artery blood flow (P<0.0001) whereas QH and PQH evoked a similar ∼1.4-fold elevation (P≤0.0018). During QH and PQH, however, tissue oxygen saturation and laser-Doppler skin blood flow in the adjacent non-heated hamstrings or quadriceps tissues remained stable (P>0.5000). These findings in healthy young humans demonstrate a tight thermo-haemodynamic coupling during regional thigh heating, providing further evidence of the importance of local heat-activated mechanisms on the control of blood circulation.

Preclinical multi-physiologic monitoring of immediate-early responses to diverse treatment strategies in breast cancer by optoacoustic imaging.

Optoacoustic imaging enables the measurement of tissue oxygen saturation (sO2) and blood perfusion while being utilized for detecting tumor microenvironments. Our aim was to employ multispectral optoacoustic tomography (MSOT) to assess immediate-early changes of hemoglobin level and sO2 within breast tumors during diverse treatments. Mouse breast cancer models were allocated into four groups: control, everolimus (EVE), paclitaxel (PTX), and photodynamic therapy (PDT). Hemoglobin was quantified daily, as well as sO2 and blood perfusion were verified by immunohistochemical (IHC) staining. MSOT showed a temporal window of enhanced oxygenation and improved perfusion in EVE and PTX groups, while sO2 consistently remained below baseline in PDT. The same results were obtained for the IHC. Therefore, MSOT can monitor tumor hypoxia and indirectly reflect blood perfusion in a non-invasive and non-labeled way, which has the potential to monitor breast cancer progression early and enable individualized treatment in clinical practice.

A novel device to assess the oxygen saturation and congestion status of the gastric conduit in thoracic esophagectomy

BackgroundIn thoracic esophagectomy, anastomotic leakage is one of the most important surgical complications. Indocyanine green (ICG) is the most widely used method to assess tissue blood flow; however, this technique has been pointed out to have disadvantages such as difficulty in evaluating the degree of congestion, lack of objectivity in evaluating the degree of staining, and bias easily caused by ICG injection, camera distance, and other factors.Evaluating tissue oxygen saturation (StO2) overcomes these disadvantages and can be performed easily and repeatedly. It is also possible to measure objective values including the degree of congestion. We evaluate novel imaging technology to assess tissue oxygen saturation (StO2) in the gastric conduit during thoracic esophagectomy.MethodsFifty patients were enrolled, with seven excluded due to intraoperative findings, leaving 43 for analysis. These patients underwent thoracic esophagectomy for esophageal cancer. The device was used intraoperatively to evaluate tissue oxygen saturation (StO2) and total hemoglobin index (T-HbI), which guided the optimal site for gastric tube anastomosis. The efficacies of StO2 and T-HbI in relation to short-term outcomes were analyzed.ResultsStO2, indicating blood supply to the gastric tube, remained stable beyond the right gastroepiploic artery (RGEA) end but significantly decreased distally to the demarcation line (p < 0.05). T-HbI, indicative of congestion, significantly decreased past the RGEA (p < 0.05). Three patients experienced anastomotic leakage. These patients exhibited significantly lower StO2 (p < 0.01) and higher T-HbI (p < 0.01) at both the RGEA end and the demarcation line. Furthermore, the anastomotic site, usually within 3 cm of the RGEA’s anorectal side, also showed significantly lower StO2 (p < 0.01) and higher T-HbI (p < 0.01) in patients with anastomotic leakage.ConclusionsThe novel device provides real-time, objective evaluations of blood flow and congestion in the gastric tube. It proves useful for safer reconstruction during thoracic esophagectomy, particularly by identifying optimal anastomosis sites and predicting potential anastomotic leakage.

The influence of carbon dioxide on cerebral metabolism and oxygen consumption: combining multimodal monitoring with dynamic systems modelling.

Hypercapnia increases cerebral blood flow. The effects on cerebral metabolism remain incompletely understood although studies show an oxidation of cytochrome c oxidase, Complex IV of the mitochondrial respiratory chain. Systems modelling was combined with previously published non-invasive measurements of cerebral tissue oxygenation, cerebral blood flow, and cytochrome c oxidase redox state to evaluate any metabolic effects of hypercapnia. Cerebral tissue oxygen saturation and cytochrome oxidase redox state were measured with broadband near infrared spectroscopy and cerebral blood flow velocity with transcranial Doppler ultrasound. Data collected during 5-min hypercapnia in awake human volunteers were analysed using a Fick model to determine changes in brain oxygen consumption and a mathematical model of cerebral hemodynamics and metabolism (BrainSignals) to inform on mechanisms. Either a decrease in metabolic substrate supply or an increase in metabolic demand modelled the cytochrome oxidation in hypercapnia. However, only the decrease in substrate supply explained both the enzyme redox state changes and the Fick-calculated drop in brain oxygen consumption. These modelled outputs are consistent with previous reports of CO2 inhibition of mitochondrial succinate dehydrogenase and isocitrate dehydrogenase. Hypercapnia may have physiologically significant effects suppressing oxidative metabolism in humans and perturbing mitochondrial signalling pathways in health and disease.