Oxygen Saturation Concentration Research Articles

Health Status and COVID-19 Epidemiology in an Inland Region of Portugal: A Retrospective Study.

Multiple factors, from socioeconomic development to genetic background, can affect the regional impact of some diseases, and this has also been seen during the COVID-19 pandemic. The objective of this retrospective study was to characterize a population in the interior of Portugal regarding health status and COVID-19 epidemiology. Between October 2021 and January 2023, 1553 subjects residing in Beira Baixa, Portugal, were included. Using a self-report approach, demographic and clinical data were obtained. Blood group, blood pressure, peripheral oxygen saturation and anti-spike protein immunoglobulin concentration were also analyzed. Statistical analysis was performed using IBM SPSS Statistics. The average age of the participants was 48.95 (±14.43) years, with 64% being male and 36% being female. The most prevalent comorbidities were hypertension (19.2%), dyslipidemia (12.6%) and diabetes mellitus (6.6%). Half of the population was overweight, and more than half of the subjects had no history of tobacco consumption. Among the participants, 33% were infected with SARS-CoV-2: 70.1% had mild disease, 14.1% moderate disease and 1.4% severe disease. There was a very significant adherence to vaccination (97%). Previously infected or vaccinated people had higher anti-spike protein immunoglobulin values; this value depended on the vaccine administered (p < 0.001). Patients with autoimmune diseases and smokers had lower levels of anti-S IgG antibodies (p = 0.030 and p = 0.024, respectively). The severity of COVID-19 did not affect the concentration of anti-S IgG (p = 0.430). This study highlights the general health statuses and the impact of COVID-19 on a population in the Portuguese interior. Knowledge of the circulation and impact of the virus in this specific population can alert and assist in better interventions being conducted by health authorities.

Studying on the in vivo pathological evolution of spinal cord injury with the rat model by the method of integrated multispectral imaging and Raman spectroscopy

Spinal cord injury (SCI) is a debilitating neurological and pathological condition that results in significant impairments in motor, sensory, and autonomic functions. By integrating multispectral imaging (MSI) with Raman spectroscopy, a label-free optical methodology was developed for achieving a non-invasive in vivo understanding on the pathological features of SCI evolution. Under the guidance of captured the spectral imaging data cube with a rigid endoscope based MSI system, a special designed fiber probe passed through the instrumental channel for acquiring the finger-print spectral information from compression rat SCI models. After identifying the main visual features of injured spinal cord tissue in all Sham, 0-, 3- and 7-days post injury (0 DPI, 3 DPI, and 7 DPI) groups, the blood volume and oxygen content were visualized to describe hemorrhage, hypoxia and inflammatory state after acute injury. The averaged reflectance spectra, which were deduced from MSI data cubes, were utilized for describing oxygen saturation and hemoglobin concentration in living tissue. The results of Raman spectroscopy addressed complex compositional and conformational phenomena during SCI progression, correlated with the well-known event like neuronal apoptosis, hemorrhage, demyelination, and even the upregulation of chondroitin sulfate proteoglycans (CSPGs). A principal component analysis and linear discriminate algorithm (PCA-LDA) based discriminate model was introduced for categorizing spectral features in different injury stages, which was applicable for intraoperative interpretations on the complex pathological courses of SCI and therapeutic outcomes.

Muscular Oxygen Saturation and Hemoglobin Concentration during Freediving: A Case Study

Muscular Oxygen Saturation and Hemoglobin Concentration during Freediving: A Case Study

New Insights into Hepatic and Intestinal Microcirculation and Pulmonary Inflammation in a Model of Septic Shock and Veno-Arterial Extracorporeal Membrane Oxygenation in the Rat.

Despite significant efforts toward improving therapy for septic shock, mortality remains high. Applying veno-arterial (V-A) extracorporeal membrane oxygenation (ECMO) in this context remains controversial. Since the cannulation of the femoral artery for V-A ECMO return leads to lower body hyperoxia, this study investigated the impact of V-A ECMO therapy on the intestinal and hepatic microcirculation during septic shock in a rodent model. Thirty male Lewis rats were randomly assigned to receive V-A ECMO therapy with low (60 mL/kg/min) or high (90 mL/kg/min) blood flow or a sham procedure. Hemodynamic data were collected through a pressure-volume catheter in the left ventricle and a catheter in the lateral tail artery. Septic shock was induced by intravenous administration of lipopolysaccharide (1 mg/kg). The rats received lung-protective ventilation during V-A ECMO therapy. The hepatic and intestinal microcirculation was measured by micro-lightguide spectrophotometry after median laparotomy for two hours. Systemic and pulmonary inflammation was detected via enzyme-linked immunosorbent assays (ELISA) of the plasma and bronchoalveolar lavage (BAL), respectively, measuring tumor necrosis factor-alpha (TNF-α), interleukins 6 (IL-6) and 10 (IL-10), and C-X-C motif ligands 2 (CXCL2) and 5 (CXCL5). Oxygen saturation and relative hemoglobin concentration were reduced in the hepatic and intestinal microcirculation during V-A ECMO therapy, independent of the blood flow rate. Further, rats treated with V-A ECMO therapy also presented elevated systolic, diastolic, and mean arterial blood pressure and increased stroke volume, cardiac output, and left ventricular end-diastolic volume. However, left ventricular end-diastolic pressure was only elevated during high-flow V-A ECMO therapy. Blood gas analysis revealed a dilutional anemia during V-A ECMO therapy. ELISA analysis showed an elevated plasma CXCL2 concentration only during high-flow V-A ECMO therapy and elevated BAL CXCL2 and CXCL5 concentrations only during low-flow V-A ECMO therapy. Rats undergoing V-A ECMO therapy exhibited impaired microcirculation of the intestine and liver during septic shock despite increased blood pressure and cardiac output. Increased pulmonary inflammation was detected only during low-flow V-A ECMO therapy in septic shock.

New Insights into Hepatic and Intestinal Microcirculation and Pulmonary Inflammation in a Model of Septic Shock and Venovenous Extracorporeal Membrane Oxygenation in the Rat.

Treatment of critically ill patients with venovenous (V-V) extracorporeal membrane oxygenation (ECMO) has gained wide acceptance in the last few decades. However, the use of V-V ECMO in septic shock remains controversial. The effect of ECMO-induced inflammation on the microcirculation of the intestine, liver, and critically damaged lungs is unknown. Therefore, the aim of this study was to measure the hepatic and intestinal microcirculation and pulmonary inflammatory response in a model of V-V ECMO and septic shock in the rat. Twenty male Lewis rats were randomly assigned to receive V-V ECMO therapy or a sham procedure. Hemodynamic data were measured by a pressure-volume catheter in the left ventricle and a catheter in the lateral tail artery. Septic shock was induced by the intravenous infusion of lipopolysaccharide (1 mg/kg). During V-V ECMO therapy, rats received lung-protective ventilation. The hepatic and intestinal microcirculation was assessed by micro-lightguide spectrophotometry after median laparotomy for 2 h. Systemic and pulmonary inflammation was measured by enzyme-linked immunosorbent assays of plasma and bronchoalveolar lavage (BAL), respectively, which included tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), IL-10, C-X-C motif ligand 2 (CXCL2), and CXCL5. Reduced oxygen saturation and relative hemoglobin concentration were measured in the hepatic and intestinal microcirculation during treatment with V-V ECMO. These animals also showed increased systolic, mean, and diastolic blood pressures. While no differences in left ventricular ejection fraction were observed, animals in the V-V ECMO group presented an increased heart rate, stroke volume, and cardiac output. Blood gas analysis showed dilutional anemia during V-V ECMO, whereas plasma analysis revealed a decreased concentration of IL-10 during V-V ECMO therapy, and BAL measurements showed increased concentrations of TNF-α, CXCL2, and CXCL5. Rats treated with V-V ECMO showed impaired microcirculation of the intestine and liver during septic shock despite increased blood pressure and cardiac output. Despite lung-protective ventilation, increased pulmonary inflammation was recognized during V-V ECMO therapy in septic shock.

Maximizing the Reliability and Precision of Measures of Prefrontal Cortical Oxygenation Using Frequency-Domain Near-Infrared Spectroscopy.

Frequency-domain near-infrared spectroscopy (FD-NIRS) has been used for non-invasive assessment of cortical oxygenation since the late 1990s. However, there is limited research demonstrating clinical validity and general reproducibility. To address this limitation, recording duration for adequate validity and within- and between-day reproducibility of prefrontal cortical oxygenation was evaluated. To assess validity, a reverse analysis of 10-min-long measurements (n = 52) at different recording durations (1-10-min) was quantified via coefficients of variation and Bland-Altman plots. To assess within- and between-day within-subject reproducibility, participants (n = 15) completed 2-min measurements twice a day (morning/afternoon) for five consecutive days. While 1-min recordings demonstrated sufficient validity for the assessment of oxygen saturation (StO2) and total hemoglobin concentration (THb), recordings ≥4 min revealed greater clinical utility for oxy- (HbO) and deoxyhemoglobin (HHb) concentration. Females had lower StO2, THb, HbO, and HHb values than males, but variability was approximately equal between sexes. Intraclass correlation coefficients ranged from 0.50-0.96. The minimal detectable change for StO2 was 1.15% (95% CI: 0.336-1.96%) and 3.12 µM for THb (95% CI: 0.915-5.33 µM) for females and 2.75% (95%CI: 0.807-4.70%) for StO2 and 5.51 µM (95%CI: 1.62-9.42 µM) for THb in males. Overall, FD-NIRS demonstrated good levels of between-day reliability. These findings support the application of FD-NIRS in field-based settings and indicate a recording duration of 1 min allows for valid measures; however, data recordings of ≥4 min are recommended when feasible.

Lagrangian dynamics of the spring zooplankton community in a large river

Zooplankton may represent a considerable part of plankton in large rivers, but little is known about the factors that control it. We hypothesized that (1) significant longitudinal increase of zooplankton abundance, biomass, taxonomic richness, and diversity will occur along a free-flowing river section; (2) the residence time of water is more important for zooplankton population growth than environmental variables such as water temperature, oxygen saturation, and food concentration; and (3) the influence of tributaries on the longitudinal dynamics of zooplankton is insignificant or only has a local effect. A Lagrangian survey was applied in the free-flowing section of the River Elbe (Germany) in spring 2022. The abundances and biomass of the dominant rotifers as well as of cladocerans and copepods increased significantly downstream due to the population growth of zooplankton. The water residence time was the most important factor for zooplankton increment. One of the tributaries increased zooplankton abundance and biomass in the River Elbe, while other tributaries did not but the introduction of new species increased taxonomic richness and decreased the evenness of zooplankton in the main river so that diversity remained nearly constant.

Validation of a Novel Noninvasive Technology to Estimate Blood Oxygen Saturation Using Green Light: Observational Study

Background Pulse oximeters work within the red-infrared wavelengths. Therefore, these oximeters produce erratic results in dark-skinned subjects and in subjects with cold extremities. Pulse oximetry is routinely performed in patients with fever; however, an elevation in body temperature decreases the affinity of hemoglobin for oxygen, causing a drop in oxygen saturation or oxyhemoglobin concentrations. Objective We aimed to determine whether our new investigational device, the Shani device or SH1 (US Patent 11191460), detects a drop in oxygen saturation or a decrease in oxyhemoglobin concentrations. Methods An observational study (phase 1) was performed in two separate groups to validate measurements of hemoglobin and oxygen concentrations, including 39 participants recruited among current university students and staff aged 20-40 years. All volunteers completed baseline readings using the SH1 device and the commercially available Food and Drug Administration–approved pulse oximeter Masimo. SH1 uses two light-emitting diodes in which the emitted wavelengths match with absorption peaks of oxyhemoglobin (hemoglobin combined with oxygen) and deoxyhemoglobin (hemoglobin without oxygen or reduced hemoglobin). Total hemoglobin was calculated as the sum of oxyhemoglobin and deoxyhemoglobin. Subsequently, 16 subjects completed the “heat jacket study” and the others completed the “blood donation study.” Masimo was consistently used on the finger for comparison. The melanin level was accounted for using the von Luschan skin color scale (VLS) and a specifically designed algorithm. We here focus on the results of the heat jacket study, in which the subject wore a double-layered heated jacket and pair of trousers including a network of polythene tubules along with an inlet and outlet. Warm water was circulated to increase the body temperature by 0.5-0.8 °C above the baseline body temperature. We expected a slight drop in oxyhemoglobin concentrations in the heating phase at the tissue level. Results The mean age of the participants was 24.1 (SD 0.8) years. The skin tone varied from 12 to 36 on the VLS, representing a uniform distribution with one-third of the participants having fair skin, brown skin, and dark skin, respectively. Using a specific algorithm and software, the reflection ratio for oxyhemoglobin was displayed on the screen of the device along with direct hemoglobin values. The SH1 device picked up more minor changes in oxyhemoglobin levels after a change in body temperature compared to the pulse oximeter, with a maximum drop in oxyhemoglobin concentration detected of 6.5% and 2.54%, respectively. Conclusions Our new investigational device SH1 measures oxygen saturation at the tissue level by reflectance spectroscopy using green wavelengths. This device fared well regardless of skin color. This device can thus eliminate racial disparity in these key biomarker assessments. Moreover, since the light is shone on the wrist, SH1 can be readily miniaturized into a wearable device.

BRIDGING GAPS: ADDRESSING TREATMENT CHALLENGES WITH ORAL PGE2 IN DUCTUS-DEPENDENT CONGENITAL HEART DEFECTS

circulation. During fetal development, it diverts approximately 90% of the right ventricular output from the high-resistance pulmonary circulation to the umbilical-placental circulation for gas exchange with maternal blood. After birth, the ductus arteriosus usually shuts within 72 hours to help with lung circulation. Failure to close leads to a persistent left-to-right shunt known as patent ductus arteriosus (PDA). PDA affects up to 80% of premature infants and constitutes 5–10% of all congenital cardiac abnormalities in term infants. Hemodynamically significant PDA is associated with various morbidities, including neurodevelopmental impairment and respiratory distress syndrome (Slaughter et al., 2019). Conversely, in ductus-dependent heart lesions, which account for 20–25% of all congenital heart defects, it is crucial to maintain patency of the neonatal DA to uphold life-saving pulmonary or systemic circulation before corrective surgery (Subramaniam and Solomon, 2013). Treatment for closing patent ductus arteriosus (PDA) mostly involves nonsteroidal anti-inflammatory medicines (NSAIDs) such as indomethacin and ibuprofen, which block cyclooxygenase enzymes necessary for prostaglandin production. Although effective, NSAIDs carry dangers such as renal impairment and intestinal problems. Acetaminophen is considered a safer option, although its effectiveness in premature infants is unclear because it may not fully inhibit prostaglandin synthesis. However, few medications exist for preserving ductus arteriosus (DA) patency, with prostaglandin E1 (PGE1) being the sole pharmacological option despite its associated side effects, such as peripheral vasodilation, apnea, fever, and physiological disturbances (Sear, 2019). Furthermore, the shortage of PGE1 in certain countries like Pakistan highlights the urgent need for alternate solutions. In such situations, adopting other available choices like PGE2, which is accessible in Pakistan as an oral drug, becomes crucial for the efficient management of ductus-dependent congenital heart anomalies. Prostaglandin E2 (PGE2) has been successfully utilized orally in newborns with ductus-dependent cyanotic congenital heart disease. In research by Silove et al., PGE2 was supplied orally in doses ranging from 12 to 65 micrograms/kg at 1 to 4 hours intervals. This treatment regimen resulted in consistent increases in oxygen saturation (SaO2) and plasma PGE2 concentrations within 15-30 minutes after administration, equivalent to those achieved with intravenous infusions. Treatment lasted for durations ranging from 5 days to 4 months, during which the ductus remained open for extended periods, allowing for delayed surgical intervention to support the growth of the infants and their pulmonary arteries. While adverse effects during oral medication were similar to those found with intravenous administration, they were generally less severe in this series, underlining the effectiveness and simplicity of oral PGE2 administration for long-term treatment (Nabavi et al., 2019). Furthermore, a 1987 study by B.D. Thanopoulos et al. supported the effectiveness of oral PGE2 in the treatment of neonates with cyanotic congenital heart disease, which primarily depends on the ductus. The data from this investigation revealed that oral PGE2 treatment, while less productive than intravenous infusions, nonetheless proved useful for long-term therapy, affording more convenience and lower morbidity (Fernández-Francos et al., 2021). It is crucial to highlight that side effects such as apnea and hypotension may occur in newborns following PGE2 therapy and require close monitoring during treatment. In conclusion, oral PGE2 offers a viable alternative for addressing congenital heart defects in resource-limited countries like Pakistan. Its effectiveness and convenience make it a viable choice, especially if access to injectable drugs is limited. This underlines the necessity to investigate alternative treatments for appropriate care in such circumstances.

Influence of cuff stiffness on hemodynamics and perceived cuff pressure in the upper extremities in males and females: implications for practical blood flow restriction training

BackgroundPractical blood flow restriction (pBFR) during exercise is a cost-saving alternative to traditional blood flow restriction using pneumatic cuffs, particularly when exercising in a group setting. Depending on the pBFR technique, several factors (e.g., cuff width, limb circumference) have already been shown to be of importance when applying the pBFR pressure. Given that elastic cuffs are often used for pBFR, the cuff stiffness might be an additional influencing factor. Therefore, the present study compared the acute effects of three elastic cuffs with identical width but different stiffness (high stiffness (HS), medium stiffness (MS), and low stiffness (LS)) on hemodynamic measures and perceived cuff pressure at rest.MethodsIn a randomized, counter-balanced cross-over study, 36 young and normotensive participants completed three experimental trials. After a 10-min rest period in supine position, the cuff was loosely and proximally applied to the right upper arm. Following baseline data recording, the cuff was successively tightened in 10%-increments with respect to the limb circumference (%overlap) until arterial blood flow was occluded. At baseline and during each %overlap, systolic peak blood flow velocity of the brachial artery, rating of perceived cuff pressure, as well as muscle oxygen saturation and total hemoglobin concentration of the biceps brachii muscle were recorded.ResultsThe %overlap required to occlude arterial blood flow was different between the three cuffs (HS: 30.9 ± 3.8%, MS: 43.9 ± 6.1%, LS: 54.5 ± 8.3%). Furthermore, at 30% overlap, systolic peak blood flow velocity was lower when applying the HS (9.0 ± 10.9 cm∙s− 1) compared to MS (48.9 ± 21.9 cm∙s− 1) and LS cuff (62.9 ± 19.1 cm∙s− 1). Rating of perceived cuff pressure at 30% overlap was higher when using the HS (6.5 ± 1.5 arbitrary unit (a.u.)) compared to MS (5.1 ± 1.4 a.u.) and LS cuff (4.9 ± 1.5 a.u.) with no difference between the MS and LS cuff. However, muscle oxygen saturation and total hemoglobin concentration were not different between the three cuffs.ConclusionsThe present study revealed that the cuff stiffness influenced blood flow velocity and arterial occlusion pressure. Therefore, cuff stiffness seems an important factor for the application of pBFR.

Blood gas parameters of Brahman cattle

Blood gas test evaluates hydroelectrolyte, acid-base balance, and lung function. The physiological parameters can be influenced by age and management and environmental factors, as well as the blood sample used: venous or arterial. The objective of this study was to analyze arterial and venous blood gas parameters of healthy Brahman cattle in Brazil, to determine reference values for this breed, comparing age and sex, in addition to evaluating the correlation between arterial and venous results. For the purpose of this research, 80 healthy cattle (40 males and 40 females) were grouped according to different age groups (Group I: from 5 to 30 days; Group II: from 31 days to 6 months; Group III: from 7 to 18 months; Group IV: from 19 to 36 months) and sex. The animals were examined by physical examination prior to the collection of the venous and arterial blood samples. Blood gas analyses were performed immediately after blood collections, using the I-STAT® portable device with EG7+ cartridge. There was a difference among age groups for rectal temperature (RT), respiratory rate (RR) and heart rate (HR), and age × sex interaction for RT and RR. Younger animals (Group I) had higher RT, HR and RR, regardless of sex. Females had higher RT than males, regardless of age. As for blood gas parameters, only oxygen pressure (PO2) and arterial and venous concentrations of sodium ions (Na+) experienced the interaction between age × sex, while pH, carbon oxygen pressure (PCO2), oxygen saturation (SO2), potassium (K+), and calcium (iCa2+) concentrations of arterial and venous blood were influenced by the age of the animals. Calves in the Group I showed the main differences in blood gas parameters compared to adults (Groups III and IV). The neonates (Group I) had lower values of pH and SO2, and higher values of PCO2, K+ and iCa2+ of arterial and venous blood. High correlation could be observed in the values of pH, Na+, hematocrit and hemoglobin when measured in arterial and venous blood, therefore, one value can be obtained by the other. The other variables were very dispersed, confirming the differences pointed out in the literature between arterial and venous blood. Finally, the results of this study can be used as a reference for healthy animals of the Brahman breed.

ANXIOLYTIC EFFECT OF A COMBINATION OF VALERIANA OFFICINALIS L. AND HUMULUS LUPULUS L. IN PATIENTS UNDERGOING IMPACTED THIRD MOLAR EXTRACTION

Introduction: Anxiety is one of the components of patient stress in the dental office and is recognized as one of the main factors that negatively affect treatment. The use of phytotherapics represents an option for the control of conventional anxiety. Thus, the objective of this study is to evaluate the effect of the association between Valeriana officinalis L. and Humulus lupulus L., on the control of anxiety in patients submitted to bilateral mandibular third molar exodonts included. Materials and Methods: Randomized, controlled, double-blind, splith-mouth, cross-over clinical trial involving a sample of 43 volunteers, after diagnosis and indication for bilateral exodontics of the included mandibular third molars, asymptomatic and in similar surgical positions and difficulties. A single oral dose of Valerian and Hops (500 mg and 120 mg, respectively) or placebo (starch) was administered randomly and crossover 1 hour before each surgical procedure. Anxiety level was assessed by physiological parameters such as heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP) and oxygen saturation content (SpO2), in three distinct phases: Phase I (baseline); Phase II (intervention day) and Phase III (return visit). Results: The herbal medicine promoted a statistically significant reduction of the PAS and PAD levels (two-way Anova with Holm-Sidak correction, p&lt;0.05) at all times of surgery when compared to placebo. The phytotherapic generated a lower degree of anxiety (Fisher's Exact test) in the evaluations of the researcher (p&lt;0.0001), operator (p&lt;0.0001) and patient (p&lt;0.0001). There were no reports of retrograde amnesia and 19 patients (51.4%) reported post-surgical muscle relaxation after use of the herbal medicine. Conclusion: The association of Valerian with Hops promotes a reduction of pressure levels, anxiety levels and has no side effects, in adult patients submitted to exodonties of the mandibular third molars included.

In vivo monitoring of hemoglobin derivatives in a rat thermal injury model using spectral diffuse reflectance imaging

IntroductionTo demonstrate the feasibility of our previously proposed Diffuse reflectance spectral imaging (DRSI) method for in vivo monitoring of oxygenated hemoglobin, deoxygenated hemoglobin, methemoglobin, tissue oxygen saturation, and methemoglobin saturation in a rat scald burn wound model and assess whether the method could be used for differentiating the burn depth groups in rats based on the hemoglobin parameters. MethodologySuperficial dermal burns (SDBs), deep dermal burns (DDBs), and deep burns (DBs) were induced in rat dorsal skin using a Walker–Mason method. An approach based on multiple regression analysis for spectral diffuse reflectance images aided by Monte Carlo simulations for light transport was used to quantify the hemoglobin parameters. Canonical discriminant analysis (CDA) was performed to discriminate SDB, DDB, and DB. ResultsCDA using the total hemoglobin concentration, tissue oxygen saturation, and methemoglobin saturation as the independent variables showed good performance for discriminating the SDB, DDB, and DB groups immediately after burn injury and the SDB group from the DDB and DB groups 24–72 h after burn injury. ConclusionsThe DRSI method with multiple regression analysis for quantification of oxygenated hemoglobin, deoxygenated hemoglobin, and methemoglobin proved to be reliable for monitoring these hemoglobin derivatives in the rat experimental burn injury model. The parameters of tissue oxygen saturation, methemoglobin saturation, and total hemoglobin concentration are promising for the differentiating the degree of burn injury using CDA.

Dissociated coupling between cerebral oxygen metabolism and perfusion in the prefrontal cortex during exercise: a NIRS study.

Purpose: The present study used near-infrared spectroscopy to investigate the relationships between cerebral oxygen metabolism and perfusion in the prefrontal cortex (PFC) during exercises of different intensities. Methods: A total of 12 recreationally active men (age 24 ± 6years) were enrolled. They performed 17min of low-intensity exercise (ExL), followed by 3min of moderate-intensity exercise (ExM) at constant loads. Exercise intensities for ExL and ExM corresponded to 30% and 45% of the participants' heart rate reserve, respectively. Cardiovascular and respiratory parameters were measured. We used near-infrared time-resolved spectroscopy (TRS) to measure the cerebral hemoglobin oxygen saturation (ScO2) and total hemoglobin concentration ([HbT]), which can indicate the cerebral blood volume (CBV). As the cerebral metabolic rate for oxygen (CMRO2) is calculated using cerebral blood flow (CBF) and ScO2, we assumed a constant power law relationship between CBF and CBV based on investigations by positron emission tomography (PET). We estimated the relative changes in CMRO2 (rCMRO2) and CBV (rCBV) from the baseline. During ExL and ExM, the rate of perceived exertion was monitored, and alterations in the subjects' mood induced by exercise were evaluated using the Profile of Moods Scale-Brief. Results: Three minutes after exercise initiation, ScO2 decreased and rCMRO2 surpassed rCBV in the left PFC. When ExL changed to ExM, cardiovascular variables and the sense of effort increased concomitantly with an increase in [HbT] but not in ScO2, and the relationship between rCMRO2 and rCBV was dissociated in both sides of the PFC. Immediately after ExM, [HbT], and ScO2 increased, and the disassociation between rCMRO2 and rCBV was prominent in both sides of the PFC. While blood pressure decreased and a negative mood state was less prominent following ExM compared with that at rest, ScO2 decreased 15min after exercise and rCMRO2 surpassed rCBV in the left PFC. Conclusion: Dissociated coupling between cerebral oxidative metabolism and perfusion in the PFC was consistent with the effort required for increased exercise intensity and associated with post-exercise hypotension and altered mood status after exercise. Our result demonstrates the first preliminary results dealing with the coupling between cerebral oxidative metabolism and perfusion in the PFC using TRS.

Point-of-Care Tissue Oxygenation Assessment with SnapshotNIR for Alloplastic and Autologous Breast Reconstruction.

Patients receiving immediate alloplastic reconstruction after mastectomy or autologous reconstruction were enrolled. Preoperative, intraoperative, and postoperative images were taken of the flaps. StO2 and hemoglobin were measured at the following locations: superior and inferior breast, free flap skin paddle (when applicable), and un-operated control skin. Linear mixed effects model for repeated measurements was used to model measurements to estimate the area effect difference across time, time effect difference across area, and pairwise comparisons between two areas at each time point. Thirty-two breasts underwent alloplastic reconstruction; 38 breasts underwent autologous reconstruction. No enrollees developed skin necrosis. StO2 was highest after mastectomy and closure in alloplastic reconstructions. StO2 was observed to decline at follow-up in autologous reconstructions. Mean preoperative StO2 was highest in breasts that had previously undergone mastectomy and alloplastic reconstruction. The SnapshotNIR device detected normal spatial and temporal differences in tissue oxygenation over the operative course of alloplastic and autologous breast reconstruction. A multi-institutional, prospective clinical trial is needed to determine the sensitivity and specificity of this device for detecting skin flap necrosis.

ACE-I/D Allele Modulates Improvements of Cardiorespiratory Function and Muscle Performance with Interval-Type Exercise.

Background: The prominent insertion/deletion polymorphism in the gene for the major modulator of tissue perfusion, angiotensin-converting enzyme (ACE-I/D) is associated with variability in adjustments in cardiac and skeletal muscle performance with standard forms of endurance and strength type training. Here, we tested whether the ACE-I/D genotype would be associated with variability in the effects of interval-type training on peak and aerobic performance of peripheral muscle and cardio-vasculature and post-exercise recovery. Methods: Nine healthy subjects (39.0 ± 14.7 years of age; 64.6 ± 16.1 kg, 173.6 ± 9.9) completed eight weeks of interval training on a soft robotic device based on repeated sets of a pedaling exercise at a matched intensity relative to their peak aerobic power output. Prior to and post-training, peak anaerobic and aerobic power output was assessed, mechanical work and metabolic stress (oxygen saturation and hemoglobin concentrations of Musculus vastus lateralis (VAS) and Musculus gastrocnemius (GAS), blood lactate and factors setting cardiac output such as heart rate, systolic and diastolic blood pressure were monitored during ramp-incremental exercise and interval exercise with the calculation of areas under the curve (AUC), which were put in relation to the produced muscle work. Genotyping was performed based on I- and D-allele-specific polymerase chain reactions on genomic DNA from mucosal swaps. The significance of interaction effects between training and ACE I-allele on absolute and work-related values was assessed with repeated measures ANOVA. Results: Subjects delivered 87% more muscle work/power, 106% more cardiac output, and muscles experienced ~72% more of a deficit in oxygen saturation and a ~35% higher passage of total hemoglobin during single interval exercise after the eight weeks of training. Interval training affected aspects of skeletal muscle metabolism and performance, whose variability was associated with the ACE I-allele. This concerned the economically favorable alterations in the work-related AUC for the deficit of SmO2 in the VAS and GAS muscles during the ramp exercise for the I-allele carriers and opposing deteriorations in non-carriers. Conversely, oxygen saturation in the VAS and GAS at rest and during interval exercise was selectively improved after training for the non-carriers of the I-allele when the AUC of tHb per work during interval exercise deteriorated in the carriers. Training also improved aerobic peak power output by 4% in the carriers but not the non-carriers (p = 0.772) of the ACE I-allele while reducing negative peak power (-27.0%) to a lesser extent in the ACE I-allele carriers than the non-carriers. Variability in cardiac parameters (i.e., the AUC of heart rate and glucose during ramp exercise, was similar to the time to recovery of maximal tHb in both muscles after cessation of ramp exercise, only associated with the ACE I-allele but not training per se. Diastolic blood pressure and cardiac output during recovery from exhaustive ramp exercise demonstrated a trend for training-associated differences in association with the ACE I-allele. Discussion: The exercise-type dependent manifestation of antidromic adjustments in leg muscle perfusion and associated local aerobic metabolism between carriers and non-carriers of the ACE I-allele with the interval-training highlight that non-carriers of the I-allele do not present an essential handicap to improve perfusion-related aerobic muscle metabolism but that the manifestation of responsiveness depends on the produced work. Conclusions: The deployed interval-type of exercise produced ACE I-allele-related differences in the alterations of negative anaerobic performance and perfusion-related aerobic muscle metabolism, which manifestation is exercise specific. The training-invariant ACE I-allele-associated differences in heart rate and blood glucose concentration emphasize that the repeated impact of the interval stimulus, despite a near doubling of the initial metabolic load, was insufficient to overturn ACE-related genetic influences on cardiovascular function.

Bilateral heel-rise test performance and physiological response are influenced by cadence and ankle position

INTRODUCTION: Different heel-rise test (HRT) protocols have been used, possibly leading to varied responses. It is necessary to analyse the impact of protocol variation on test responses. PURPOSE: To compare the performance, muscle oxygenation (MO), and heart rate (HR) responses of adults in bilateral HRT protocols. METHODS: This was a cross-sectional crossover study.Thirty participants (23.1±2.9 years; 16 men) performed four bilateral HRT protocols with varying cadence (self-cadenced; externally cadenced) and ankle position (neutral; dorsiflexion). For MO responses, we analysed tissue oxygen saturation (StO2) and oxyhemoglobin concentration variation (∆[O2Hb]) and calculated the variation between the smallest and final values (∆Nadir-Final) and the area under the curve (AUC). The variation between the initial and final HR values (∆HR) and the time constant (τ) were calculated. Friedman's test was used to compare the variables among the protocols. Two-way ANOVA was used to identify the impact of cadence and/or ankle position. RESULTS: The number of repetitions and execution time were higher in the neutral position and externally cadenced protocols (p&lt;0.001 for both). ∆Nadir-Final (StO2: p&lt;0.001; ∆[O2Hb]: p=0.005) and AUC (StO2: p&lt;0.001; ∆[O2Hb]: p&lt;0.001) of both MO variables were higher in the neutral position protocols. Self-cadenced protocols presented higher HR increase and faster τ (p=0.006 and p=0.046). CONCLUSION: Bilateral HRT performed in a neutral position, and external cadence promotes more repetitions and a longer execution time. Dorsiflexion promotes lower muscle reperfusion, and self-cadence higher and faster HR increase.

Optical Spectral Approach to Breast Tissue Oxygen Saturation Analysis for Mastectomy Perioperative Control

The purpose of our research is to study the ability of the developed method of hemoglobin detection, based on the fiber-optic spectral analysis in visible region, to determine the level of blood supply to breast tissues before surgical treatment, intraoperatively and during observation of the patient in the postoperative period, when breast tissue is healing. The significant effect of subcutaneous adipose tissue on the shape of diffuse reflectance spectra due to scattering leads to a decrease in the accuracy of determining hemoglobin oxygen saturation and hemoglobin concentration from them. The variability of the subcutaneous adipose tissue layer is quite high, which also leads to a high variability of the spectra within a class of tissues that are in the same physiological state, which implies that the intraclass variability due to this factor should be assessed for a specific problem, not considering it random. For this purpose, in our work, we constructed optical phantoms simulating various thicknesses of the subcutaneous adipose tissue in order to determine the effect of its light scattering on the diffuse reflectance spectrum and to select the optimal configuration of optical fibers.

In vivo spectroscopic evaluation of human tissue optical properties and hemodynamics during HPPH-mediated photodynamic therapy of pleural malignancies.

Dosimetry for photodynamic therapy is dependent on multiple parameters. Critically, in vivo tissue optical properties and hemodynamics must be determined carefully to calculate the total delivered light dose. Spectroscopic analysis of diffuse reflectance measurements of tissues taken during a clinical trial of 2-(1-hexyloxyethyl)-2-devinyl pyropheophorbide-a-mediated photodynamic therapy for pleural malignancies. Diffuse reflectance measurements were taken immediately before and after photodynamic therapy. Measurements were analyzed with a nonlinearly constrained multiwavelength, multi-distance algorithm to extract tissue optical properties, tissue oxygen saturation, StO2, and total hemoglobin concentration (THC). A total of 25 patients were measured, 23 of which produced reliable fits for optical property extraction. For all tissue types, StO2 ranged through [24, 100]% and [22, 97]% for pre-photodynamic therapy (PDT) and post-PDT conditions, respectively. Mean THC ranged through [ 69,152 ] μM and [ 48,111 ] μM, for pre-PDT and post-PDT, respectively. Absorption coefficients, μa, ranged through [ 0.024 , 3.5 ] cm - 1 and [ 0.039 , 3 ] cm - 1 for pre-PDT and post-PDT conditions, respectively. Reduced scattering coefficients, μs', ranged through [ 1.4 , 73.4 ] cm - 1 and [ 1.2 , 64 ] cm - 1 for pre-PDT and post-PDT conditions, respectively. There were similar pre- and post-PDT tissue optical properties and hemodynamics. The high variability in each parameter for all tissue types emphasizes the importance of these measurements for accurate PDT dosimetry.

Observed and projected global warming pressure on coastal hypoxia

Abstract. Coastal hypoxia is a major environmental problem of increasing severity. A global 40-year observational gridded climate data record and 21st-century projections from the Community Earth System Model (CESM) under RCP8.5 (Representative Concentration Pathway) forcing are analyzed for long-term linear trends in summer-month conditions, with a focus on warming-related pressures on coastal oxygen levels. Projected surface temperature and oxygen conditions are compared to global observations over the 16-year overlapping period (2006–2021). Median linear trends for 2006–2100 along the global coast are 0.32 ∘C, −1.6, and −1.2 mmol m−3 per decade for sea-surface temperature (SST), oxygen saturation concentration at the surface (surface oxygen capacity), and vertical-minimum oxygen concentration, respectively. These trends point to more rapid deterioration in coastal conditions than experienced over recent decades; the projected median coastal trends for SST and oxygen capacity are 148 % and 118 % of the corresponding observed rates. Companion analysis of other models and climate scenarios indicates projected coastal oxygen trends for the more moderate RCP4.5 and updated SSP5–8.5 (Shared Socioeconomic Pathway) scenarios, respectively, are 37 %–77 % and 103 %–196 % of the CESM RCP8.5 projections. Median rates for the coast and documented hypoxic areas are higher than in the global ocean. Warming and oxygen declines tend to be fastest at high latitudes, one region where new hypoxic areas may emerge as oxygen conditions deteriorate. There is considerable pressure on current hypoxic areas, since future oxygen declines of any magnitude will make hypoxia more severe. The projections can inform coastal environmental management strategies to protect future water quality and ecosystem services.