Blood Oxygen Research Articles

Reassessing the Functional Significance of Blood Oxygen Level Dependent Signal Variability.

BOLD signal variability (SDBOLD) has emerged as a unique measure of the adaptive properties of neural systems that facilitate fast, stable responding, based on claims that SDBOLD is independent of mean BOLD signal (meanBOLD) and is a powerful predictor of behavioral performance. We challenge these two claims. First, the apparent independence of SDBOLD and meanBOLD may reflect the presence of deactivations; we hypothesize that although SDBOLD may not be related to raw meanBOLD, it will be linearly related to "absolute" meanBOLD. Second, the observed relationship between SDBOLD and performance may be an artifact of using fixed-length trials longer than RTs. Such designs provide opportunities to toggle between on- and off-task states, and fast responders likely engage in more frequent state-switching, thereby artificially elevating SDBOLD. We hypothesize that SDBOLD will be higher and more strongly related to performance when using such fixed-length trials relative to self-paced trials that terminate upon a response. We test these two hypotheses in an fMRI study using blocks of fixed-length or self-paced trials. Results confirmed both hypotheses: (1) SDBOLD was robustly related with absolute meanBOLD, and (2) toggling between on- and off-task states during fixed-length trials reliably contributed to SDBOLD. Together, these findings suggest that a reappraisal of the functional significance of SDBOLD as a unique marker of cognitive performance is warranted.

The differential effects of dyslipidemia status and triglyceride-glucose index on left ventricular global function and myocardial microcirculation in diabetic individuals: a cardiac magnetic resonance study

BackgroundIt remains unclear whether the association between dyslipidemia status and triglyceride-glucose (TyG) index with myocardial damage varies in the context of type 2 diabetes mellitus (T2DM). This study aimed to determine the differential effects of dyslipidemia status and TyG index on left ventricular (LV) global function and myocardial microcirculation in patients with T2DM using cardiac magnetic resonance (CMR) imaging.MethodsA total of 226 T2DM patients and 72 controls who underwent CMR examination were included. The T2DM group was further categorized into subgroups based on the presence or absence of dyslipidemia (referred to as T2DM (DysL+) and T2DM (DysL-)) or whether the TyG index exceeded 9.06. CMR-derived LV perfusion parameters, remodeling index, and global function index (GFI) were assessed and compared among groups. A multivariable linear regression model was employed to evaluate the effects of various variables on LV myocardial microcirculation, remodeling index, and GFI.ResultsThe LV GFI sequentially decreased in controls, T2DM (DysL-), and T2DM (DysL+) groups (p < 0.001), and was lower (p = 0.003) in T2DM with higher TyG index group than in lower TyG index group. The LV remodeling index was higher in higher TyG index group than in lower TyG index group (p = 0.002), but there was no significant difference in whether the subgroup was accompanied by dyslipidemia. Multivariable analysis revealed that the TyG index, but not dyslipidemia status, was independently associated with LV remodeling index (β coefficient[95% confidence interval], 0.152[0.025, 0.268], p = 0.007) and LV GFI (− 0.159[− 0.281, − 0.032], p = 0.014). For LV myocardial microcirculation, perfusion index, upslope, and max signal intensity sequentially decreased in controls, T2DM (DysL-), and T2DM (DysL+) groups (all p < 0.001). Dyslipidemia status independently correlated with perfusion index (− 0.147[− 0.272, − 0.024], p = 0.02) and upslope (− 0.200[− 0.320, 0.083], p = 0.001), while TyG index was independently correlated with time to maximum signal intensity (0.141[0.019, 0.257], p = 0.023).ConclusionsBoth dyslipidemia status and higher TyG index were associated with further deterioration of LV global function and myocardial microvascular function in the context of T2DM. The effects of dyslipidemia and a higher TyG index appear to be differential, which indicates that not only the amount of blood lipids and glucose but also the quality of blood lipids are therapeutic targets for preventing further myocardial damage.

Testing a Consumer Wearables Program to Promote the Use of Positive Airway Pressure Therapy in Patients With Obstructive Sleep Apnea: Protocol for a Pilot Randomized Controlled Trial.

Although positive airway pressure (PAP) therapy is considered first-line treatment for obstructive sleep apnea (OSA), nonadherence is common. Numerous factors influence PAP use, including a belief that the therapy is important and effective. In theory, providing information to patients about their blood oxygen levels during sleep (which may be low when PAP is not used), juxtaposed to information about their PAP use, may influence a patient's beliefs about therapy and increase PAP use. With the advent of consumer wearable smartwatches' blood oxygen saturation monitoring capability (and the existing routine availability of PAP use data transmitted via modem to clinical dashboards), there is an opportunity to provide this combination of information to patients. This study aims to test the feasibility, acceptability, and preliminary efficacy of the Chronic Care Management With Wearable Devices in Patients Prescribed Positive Airway Pressure Therapy (mPAP), a program that augments current PAP therapy data with consumer-grade wearable device to promote self-management of PAP therapy for OSA in a pilot randomized waitlist-controlled clinical trial. This is a single-blinded randomized controlled trial. We will randomize 50 individuals with a history of OSA, who receive care from a Department of Veterans Affairs medical center in the Los Angeles area and are nonadherent to prescribed PAP therapy, into either an immediate intervention group or a waitlist control group. During a 28-day intervention, the participants will wear a study-provided consumer wearable device and complete a weekly survey about their OSA symptoms. A report that summarizes consumer wearable-provided oxygen saturation values, PAP use derived from modem data, and patient-reported OSA symptoms will be prepared weekly and shared with the patient. The immediate intervention group will begin intervention immediately after randomization (T1). Assessments will occur at week 5 (T3; 1 week after treatment for the immediate intervention group and repeat baseline for the waitlist control group) and week 11 (T5; follow-up for the immediate intervention group and 1 week after treatment for the waitlist control group). The primary outcome will be the change in 7-day PAP adherence (average minutes per night) from T1 to T3. The primary analysis will be a comparison of the primary outcome between the immediate intervention and the waitlist control groups (intention-to-treat design), using a 2-sample, 2-sided t test on change scores (unadjusted). Recruitment began in October 2023. Data analysis is expected to begin in October 2024 when all follow-ups are complete, and a manuscript summarizing trial results will be submitted following completion of data analysis. Findings from the study may provide additional insights on how patients with OSA might use patient-generated health data collected by consumer wearables to inform self-management of OSA and possibly increase their use of PAP therapy. ClinicalTrials.gov NCT06039865; https://clinicaltrials.gov/study/NCT06039865. DERR1-10.2196/60769.

Enhancing hemodynamic stability: the role of liaison nurses in patient transfers to angiography

IntroductionAngiography is associated with anxiety, stress, and changes in patients’ vital signs. The role of the liaison nurse is to bridge gaps and solve problems between departments, thereby preventing the occurrence of undesired complications during patient transfers. Proper preparation of patients by the liaison nurse may lead to an improvement in the hemodynamic status of patients. The present study was conducted to investigate the effect of liaison nurse on hemodynamic status during transfer process to angiography.MethodThis randomized controlled trial was conducted from December 2019 to March 2020 on 62 patients who were candidates for elective angiography at Imam Reza Hospital in Mashhad. Participants were selected using a convenience sampling method and then randomly assigned to either the control or intervention group using a lottery system. In the intervention group, patients benefited from the presence of a liaison nurse from the moment the transfer order was issued by the doctor. Tools used included a demographic information questionnaire and a hemodynamic signs checklist. Data were analyzed using SPSS 25 with independent T-tests, paired T-tests, Wilcoxon, Mann-Whitney test, chi-squared, and Fisher’s exact test.ResultFollowing the intervention, the mean systolic blood pressure, heart rate, and respiratory rate in the intervention group were found to be significantly lower than those in the control group (p < 0.05). In contrast, the mean body temperature, diastolic blood pressure and the percentage of arterial blood oxygen saturation did not exhibit a statistically significant difference between the two groups (p > 0.05).ConclusionThe liaison nurse role emerges as a valuable strategy for enhancing patients’ hemodynamic stability, and its implementation can have a positive impact on patient outcomes in hospital settings.

Evaluation of perfusion index to predict hypotension in lower segment caesarean section under spinal anaesthesia

Background: Spinal Anaesthesia is the most popular choice for elective caesarean section. Both general anaesthesia and regional anaesthesia are acceptable techniques for anaesthesia for elective and emergency caesarean sections. Objectives: The study aimed to investigate the role of the perfusion index in predicting the incidence of hypotension following spinal anaesthesia in parturients undergoing elective lower segment caesarean sections. Methods: A prospective, observational study was carried out among sixty parturients posted for elective caesarean section. The study was conducted in the operation theatres of Vardhman Mahavir Medical College and Safdarjung Hospital, New Delhi. About 60 participants were interviewed for the study. Data were entered and analysed with the help of the Statistical Package for Social Science (SPSS) version.16. Results: Sixty eligible ASAI (American society of anaesthesiologist’s physical status classification) parturients scheduled for elective caesarean section were divided into two groups pre-operatively after determining their baseline Perfusion Index (PI) as those with PI ≤ 3.5 and those with PI &gt; 3.5 using a Masimo® pulse oximeter probe. When comparing the heart rate at time intervals among the two groups, it became increasingly clear that those with baseline PI &gt; 3.5 had generally higher heart rate especially immediately after the block and at 2nd, 4th, 6th,8th, 10th, 12th, 14th and 20th minutes. Conclusion: The study concludes that a Perfusion Index &gt; 3.5 is associated with a higher incidence of hypotension in lower segment caesarean section under spinal anaesthesia. The hemodynamic parameters such as increased heart rate and significantly lower systolic, diastolic and mean arterial pressures in parturients with baseline PI &gt; 3.5 suggest that these patients have lower baseline SVR and depleted autonomic resilience to hypotension compared to those with baseline PI ≤ 3.5. High BMI seems to be significantly associated with high baseline PI.

Effects of moderate alcohol consumption and hypobaric hypoxia: implications for passengers’ sleep, oxygen saturation and heart rate on long-haul flights

BackgroundPassengers on long-haul flights frequently consume alcohol. Inflight sleep exacerbates the fall in blood oxygen saturation (SpO2) caused by the decreased oxygen partial pressure in the cabin. We investigated the...

Perfusion imaging metrics after acute traumatic spinal cord injury are associated with injury severity in rats and humans.

Traumatic spinal cord injury (tSCI) causes an immediate loss of neurological function, and the prediction of recovery is difficult in the acute phase. In this study, we used contrast-enhanced ultrasound imaging to quantify intraspinal vascular disruption acutely after tSCI. In a rodent thoracic tSCI model, contrast-enhanced ultrasound revealed a perfusion area deficit that was positively correlated with injury severity and negatively correlated with hindlimb locomotor function at 8 weeks after injury. The spinal perfusion index was calculated by normalizing the contrast inflow at the injury center to the contrast inflow in the injury periphery. The spinal perfusion index decreased with increasing injury severity and positively correlated with hindlimb locomotor function at 8 weeks after injury. The feasibility of intraoperative contrast-enhanced ultrasound imaging was further tested in a cohort of 27 patients with acute tSCI of varying severity and including both motor-complete and motor-incomplete tSCIs. Both the perfusion area deficit and spinal perfusion index were different between motor-complete and motor-incomplete patients. Moreover, the perfusion area deficit and spinal perfusion index correlated with the injury severity at intake and exhibited a correlation with extent of functional recovery at 6 months. Our data suggest that intraoperative contrast-enhanced, ultrasound-derived metrics are correlated with injury severity and chronic functional outcome after tSCI. Larger clinical studies are required to better assess the reliability of the proposed contrast-enhanced ultrasound biomarkers and their prognostic capacity.

Testing preload responsiveness by the tidal volume challenge assessed by the photoplethysmographic perfusion index

BackgroundTo detect preload responsiveness in patients ventilated with a tidal volume (Vt) at 6 mL/kg of predicted body weight (PBW), the Vt-challenge consists in increasing Vt from 6 to 8 mL/kg PBW and measuring the increase in pulse pressure variation (PPV). However, this requires an arterial catheter. The perfusion index (PI), which reflects the amplitude of the photoplethysmographic signal, may reflect stroke volume and its respiratory variation (pleth variability index, PVI) may estimate PPV. We assessed whether Vt-challenge-induced changes in PI or PVI could be as reliable as changes in PPV for detecting preload responsiveness defined by a PLR-induced increase in cardiac index (CI) ≥ 10%.MethodsIn critically ill patients ventilated with Vt = 6 mL/kg PBW and no spontaneous breathing, haemodynamic (PICCO2 system) and photoplethysmographic (Masimo-SET technique, sensor placed on the finger or the forehead) data were recorded during a Vt-challenge and a PLR test.ResultsAmong 63 screened patients, 21 (33%) were excluded because of an unstable PI signal and/or atrial fibrillation and 42 were included. During the Vt-challenge in the 16 preload responders, CI decreased by 4.8 ± 2.8% (percent change), PPV increased by 4.4 ± 1.9% (absolute change), PIfinger decreased by 14.5 ± 10.7% (percent change), PVIfinger increased by 1.9 ± 2.6% (absolute change), PIforehead decreased by 18.7 ± 10.9 (percent change) and PVIforehead increased by 1.0 ± 2.5 (absolute change). All these changes were larger than in preload non-responders. The area under the ROC curve (AUROC) for detecting preload responsiveness was 0.97 ± 0.02 for the Vt-challenge-induced changes in CI (percent change), 0.95 ± 0.04 for the Vt-challenge-induced changes in PPV (absolute change), 0.98 ± 0.02 for Vt-challenge-induced changes in PIforehead (percent change) and 0.85 ± 0.05 for Vt-challenge-induced changes in PIfinger (percent change) (p = 0.04 vs. PIforehead). The AUROC for the Vt-challenge-induced changes in PVIforehead and PVIfinger was significantly larger than 0.50, but smaller than the AUROC for the Vt-challenge-induced changes in PPV.ConclusionsIn patients under mechanical ventilation with no spontaneous breathing and/or atrial fibrillation, changes in PI detected during Vt-challenge reliably detected preload responsiveness. The reliability was better when PI was measured on the forehead than on the fingertip. Changes in PVI during the Vt-challenge also detected preload responsiveness, but with lower accuracy.

ITRAQ Based Proteomics Reveals the Potential Mechanism of Placental Injury Induced by Prenatal Stress

Maternal stress experienced during prenatal development is recognized as a significant risk factor for neurodevelopmental and neuropsychiatric disorders across the offspring’s lifespan. The placental barrier serves a crucial function in safeguarding the fetus from detrimental exposures during gestation. However, previous investigations have not yet comprehensively elucidated the extensive connections between prenatal stress and the expression of placental proteins. In this study, we used iTRAQ-based quantitative proteomics to elucidate the placental adaptive mechanisms of pregnant rats in response to fear-induced stress. Our results showed that during pregnancy, exposure to fear-induced stress led to a pathological hypercoagulable state in the mother’s body. Placental circulation was also disrupted, significantly reducing placental efficiency and blood oxygen saturation in newborn rats. Proteomic analyses showed that most of the DEPs were annotated to the PI3K-Akt and ECM-receptor interaction signaling pathway. In addition, the expressions of CDC37, HSP90β, AKT, p-AKT and p-mTOR were down-regulated significantly in the placenta. Our results demonstrated that prenatal fear-induced stress led to inhibition of the cellular signal transduction of placental PI3K/AKT/mTOR, which affected biological processes such as rRNA processing, translation, protein folding, protein stability, and oxygen transport in the placenta. These abnormalities in biological functions could potentially damage the barrier function of the placenta and thereby result in abnormal development in the offspring.

Justification of the possibility of using liquid artificial lung ventilation for the treatment of acute respiratory distress syndrome of toxic genesis

Introduction. Pulmonotoxicants are chemicals that cause bronchospasm and damage to the alveolar capillary membrane. Lesions of the respiratory system with pulmonotoxicants in industrial accidents are especially relevant at the present time. Existing methods of treatment for the defeat of pulmonotoxicants and the development of acute respiratory distress syndrome (ARDS) are becoming ineffective, therefore, one of the tasks of modern medicine is to develop new methods of treating ARDS. One of these methods may be the creation of a "therapeutic window" by using perfluorocarbon (PFC) liquids. This article will present an experimental assessment of the use of liquid artificial lung ventilation (LALV) PFC liquids on the ARDS lung model. The study aims to explore the possibility of using liquid artificial lung ventilation to create a therapeutic window in the treatment of acute respiratory distress syndrome of a chemical nature. Materials and methods. The authors conducted a study on male Wistar rats aged 4 months, weighing 180–190 g. Toxic pulmonary edema was caused by endotracheal administration of 0.1 m HCl solution. The anesthetized patients were intubated using a cannula, after which the researchers intratracheally injected 0.1 M HCl solution at a dose of 2 ml/kg, a decrease in saturation below 80 was expected. Then the experts randomized the animals by weight into groups of 6 individuals each. They connected the animals of the control group to a ventilator. The animals of the experimental group were treated with PFC liquids for an hour, then transferred to a ventilator. Perfluorodecalin was used as a PFC liquid. The scientists recorded heart rate, blood oxygen saturation, rectal temperature, life expectancy and overall survival by group. Results. In the control group, after instillation of 0.1 M HCl solution and connection to a ventilator during the first 25–30 minutes, there was a gradual decrease in SpO2 to 74.0±5.6% (background — 95.0±3.5%) and an increase in heart rate to 182.0±8.6 beats/min., (background — 278.0±14.8 beats/min.) after which there was decompensation of the animal condition. In animals of the experimental group, after connecting to the LALV device, a sharp decrease in heart rate was recorded during the first 5 minutes to 61.0±8.5 beats/min. In turn, saturation did not change significantly throughout the LALV and was in the range from 95 to 100%. As a result of the experiments, it was noted that the average survival time in the experimental group was 256.0±34.5 minutes, which was significantly (p&lt;0.001) more than 5 times higher than this indicator in the control animals — 45.3±4.3 minutes. There were no significant changes in the study of rectal temperature in the animals of the control group. In turn, the animals of the experimental group showed a sharp decrease in rectal temperature during the first 30 minutes from the beginning of LALV, on average by 5.8±1.60°С. As a result of the pathoanatomic autopsy, differences in lung mass coefficients were revealed in different groups. Thus, in the control group and the experimental groups, it was 1.67±0.06 and 2.4±0.045%, respectively. Conclusion. On the model of ARDS caused by endotracheal administration of 0.1M hydrochloric acid solution, it was shown that living with the use of PFC of low temperature liquids, unlike conventional mechanical ventilation, allows for a long time to maintain a stable condition of animals; evacuate a significant amount of edematous fluid from the lungs and thereby increase the duration of their survival. The data presented above indicate that the use of hypothermic LALV can be used to create a "therapeutic window" for ARDS, including its most severe form — the alveolar stage of toxic pulmonary edema. Ethics. Studies involving laboratory animals were conducted in compliance with the following regulations: the Helsinki Declaration of 2000 "On humane treatment of animals", Order No. 755 of the Ministry of Health of the USSR dated 08/12/1977 "Rules for carrying out work using experimental animals", Order No. 199n of the Ministry of Health of the Russian Federation dated 04/01/2016 "On approval of the rules of laboratory practice". The protocol of the study was approved by the Ethics Committee of the Izmerov Research Institute of Occupational Health. Protocol No. 4 dated May 25, 2022.

Type 2 diabetes mellitus negatively affects the functional performance of 6-min step test in chronic heart failure: a 3-year follow-up study

BackgroundType 2 diabetes mellitus (T2DM) and chronic heart failure (CHF) present a decrease in functional capacity due to the intrinsic nature of both pathologies. It is not known about the potential impact of T2DM on functional capacity when assessed by 6-min step test (6MST) and its effect as a prognostic marker for fatal and non-fatal events in patients with CHF.Objectiveto evaluate the coexistence of T2DM and CHF in functional capacity through 6MST when compared to CHF non-T2DM, as well as to investigate the different cardiovascular responses to 6MST and the risk of mortality, decompensation of CHF and acute myocardial infarction (AMI) over 36 months.MethodsThis is a prospective cohort study with 36 months of follow-up in individuals with T2DM and CHF. All participants completed a clinical assessment, followed by pulmonary function testing, echocardiography, and 6MST. The 6MST was performed on a 20 cm high step and cardiovascular responses were collected: heart rate, systemic blood pressure, oxygen saturation, BORG dyspnea and fatigue. The risk of mortality, acute myocardial infarction and decompensation of CHF was evaluated.ResultsEighty-six participants were included. The CHF-T2DM group had a significantly lower functional capacity than the CHF non-T2DM group (p < 0.05). Forced Expiratory Volume in one second (L), ejection fraction (%), gender and T2DM influence and are predictors of functional capacity (p < 0.05; adjusted R squared: 0.419). CHF-T2DM group presented a higher risk of mortality and acute myocardial infarction over the 36 months of follow-up (p < 0.05), but not to the risk of decompensation (p > 0.05).ConclusionT2DM negatively affects the functional performance of 6MST in patients with CHF. Gender, ejection fraction (%), FEV1 (L) and T2DM itself negatively influence exercise performance.

Functional conductivity imaging: quantitative mapping of brain activity.

Theory and modelling suggest that detection of neuronal activity may be feasible using phase sensitive MRI methods. Successful detection of neuronal activity both in vitro and in vivo has been described while others have reported negative results. Magnetic resonance electrical properties tomography may be a route by which signal changes can be identified. Here, we report successful and repeatable detection at 3 Tesla of human brain activation in response to visual and somatosensory stimuli using a functional version of tissue conductivity imaging (funCI). This detects activation in both white and grey matter with apparent tissue conductivity changes of 0.1 S/m (17-20%, depending on the tissue baseline conductivity measure) allowing visualization of complete system circuitry. The degree of activation scales with the degree of the stimulus (duration or contrast). The conductivity response functions show a distinct timecourse from that of traditional fMRI haemodynamic (BOLD or Blood Oxygenation Level Dependent) response functions, peaking within milliseconds of stimulus cessation and returning to baseline within 3-4s. We demonstrate the utility of the funCI approach by showing robust activation of the lateral somatosensory circuitry on stimulation of an index finger, on stimulation of a big toe or of noxious (heat) stimulation of the face as well as activation of visual circuitry on visual stimulation in up to five different individuals. The sensitivity and repeatability of this approach provides further evidence that magnetic resonance imaging approaches can detect brain activation beyond changes in blood supply.

The impact of hypoxic training at different altitudes on human physiology, biochemistry, and cytogenetics

This study investigated the impact of dosed hypoxic normobaric exercises on the physio-biochemical parameters of blood and lymph circulation, as well as cytogenetic changes in red blood cells (RBC), using a Sprague Dawley Rat Model. Hypoxic training was conducted in an animal hypoxic chamber. The session lasted 34-35 minutes. The O2 content was 20.5% at the beginning of the session; then, it dropped to 14.8% within 4-5 minutes, corresponding to a rise to an altitude of 2,900-3,000 m, and was maintained at that level until the end of the session. The hypoxic training cycle increased the RBC count by 4.1%, the hemoglobin count by 4.2%, the blood oxygen capacity by 8.3%, the circulating blood volume by 16.7%, and interstitial metabolism and lymph circulation by 30.6%. A cytogenetic study revealed an increase in erythropoiesis-reticulocyte count by 40.3% and a slightly higher frequency of micronucleated erythrocytes. We observed economization of the heart, respiration, activation of glucose transport by 33.5%, increased lipid utilization, and increased antioxidant protection. These parameters especially changed when hypoxic training was combined with physical activity. Hypoxic training with physical activity expands the body’s compensatory and adaptive capabilities by increasing the reserves of the respiratory, cardiovascular, and lymphatic systems.

Association between resting-state neurovascular coupling and neural signals as revealed by a combined fMRI and magnetoencephalography (MEG) study in humans.

The Blood Oxygenation Level-Dependent (BOLD) activation reflects hemodynamic events mediated by neurovascular coupling. During task performance, the BOLD hemodynamic response in a relevant area is mainly driven by the high levels of synaptic activity (reflected in local field potentials, LFP) but, in contrast, during a task-free, resting state, the contribution to BOLD of such neural events is small, as expected by the comparatively (to the task state) low level of neural events. Concomitant recording of BOLD and LFP at rest in animal experiments has estimated the neural contribution to BOLD to ~10%. Such experiments have not been performed in humans. As an approximation, we recorded (in the same subject, N = 57 healthy participants) at a task-free, resting state the BOLD signal and, in a different session, the magnetoencephalographic (MEG) signal, which reflects purely neural (synaptic) events. We then calculated the turnover of these signals by computing the successive moment-to-moment difference in the BOLD and MEG time series and retaining the median of the absolute value of the differenced series (TBOLD and TMEG, respectively). A linear regression of normalized TBOLD vs. TMEG revealed that ~30% of TMEG contributes to TBOLD, accounting for 11.3% of the latter's variance. This percentage estimate is close to the ~10% estimate above obtained by direct recordings in animal experiments.

Exploring the Non-Invasive Methods of Brain- Computer Interface: A Comprehensive Review of their Advances and Applications

The brain-computer interface technology allows the human brain to control external devices directly without using the brain’s output channels or peripheral nerves. It helps individuals with motor impairments to use mechanical and external devices to communicate with the outside world. Non-invasive BCIs allow communication between the human brain and external devices without the need for surgeries or invasive procedures. Methods like EEG, MEG, fMRI, and fNIRS are used. EEG enables the acquisition of electrical activity along the scalp by measuring voltage fluctuations and neurotransmission activity in the brain. The electrodes are attached to a cap-like device and are placed on the scalp to record the electrical current generated by the brain. Unlike MEG, which necessitates specially constructed rooms, EEG is portable. Lab-grade EEG is expensive but cheaper than other forms of BCI. MEG uses magnetometers to measure magnetic fields produced by electric currents occurring naturally in the brain. MEG is better than EEG at measuring high-frequency activity. MEG signals are less distorted by the skull layer. FMRI records blood oxygen level-dependent (BOLD) signals with high spatial resolution across the entire brain. It does this by tracking the hemodynamic response, which is the increase in blood flow to active brain areas. It does this using the principle of nuclear magnetic resonance, where hydrogen atoms in water molecules in the blood emit signals when subjected to a strong magnetic field. It has an advantage over EEG due to its superior spatial specificity and resolution. FNIRS measures the blood flow and oxygenation in the blood associated with neural activity. It gains insight into the brain's hemodynamic response, which is essential for understanding neural functioning during BCI tasks.

Commentary: COVID-19 impairs oxygen delivery by altering red blood cell hematological, hemorheological, and oxygen transport properties

Commentary: COVID-19 impairs oxygen delivery by altering red blood cell hematological, hemorheological, and oxygen transport properties

Polyvinyl alcohol-chitosan based oleanolic acid nanofibers against bacterial infection: In vitro studies and in vivo evaluation by optical and laser Doppler imaging modalities

The present work focuses on the fabrication of polyvinyl alcohol-chitosan-loaded oleanolic acid-nanofibers (PVA-CS-OLA-NFs) for bacterial infection. The prepared PVA-CS-OLA-NFs were characterized for contact angle, SEM, AFM, XRD, FTIR, and TGA. The solid-state characterization and in vitro performance evaluation of nanofibers reveal consistent interconnection and diameters ranging from 102 ± 9.5 to 386 ± 11.6 nm. The nanofibers have a flat surface topography and exhibit efficient drug entrapment. Moreover, the in vitro release profile of PVA-CS-OLA-NFs was found to be 51.82 ± 1.49 % at 24 h. Furthermore, the hemocompatibility study showed that the developed PVA-CS-OLA-NFs are non-hemolytic to human blood. The PVA-CS-OLA-NFs demonstrate remarkable antibacterial capabilities, as evidenced by their MBC and MIC values, which range from 128 and 32 μg/mL, against the strains of S. aureus. The in-vivo fluorescence optical imaging showed the sustained PVA-CS-OLA-NFs release at the wound site infected with S. aureus for a longer duration of time. Moreover, the PVA-CS-OLA-NFs showed superior wound healing performance against S. aureus infected wounds compared to the marketed formulation. Further, the laser Doppler imaging system improved oxygen saturation, blood supply, and wound healing by providing real-time blood flow and oxygen saturation information.

Insights into the baseline blood pH homeostasis at admission and the risk of in-hospital mortality in COVID-19 patients.

Aim: A laboratory finding in critically ill COVID-19 patients is blood academia (pH <7.35). We investigated its cause in connection with the admission baseline blood pH homeostasis.Patients & methods: We retrospectively monitored the baseline blood pH homeostasis of 1215 COVID-19 patients who were admitted with pneumonia using data-driven knowledge. Two categories of patients were identified: non-survivors (107) and survivors (1108).Results: Non-survivors showed greater levels of lactate and lower blood pH, saturation, and partial pressure of oxygen than survivors. A bivariate Spearman's correlation matrix showed that the [HCO3-]/pCO2 and pCO2 of non-survivors exhibited an unmatched connection, but not in the survivor group. When comparing non-survivors to survivors, the dendrograms derived from the bivariate comparison matrix showed differences in gasometry parameters like blood pH, [HCO3-]/pCO2 ratio, anion gap and pO2.Conclusion: The little variations in the gasometry readings between survivors and non-survivors upon admission suggested abnormal changes in the complementary renal and respiratory systems that bring blood pH back to normal. In advanced COVID-19, modest blood acid-base imbalances could become blood acidemia if these compensatory strategies were overused. Data-driven monitoring of acid-base parameters may help predict abnormal blood pH and the advancement of metabolic acidemia before it is too late.

Pilot study of home-based monitoring for early prediction of acute exacerbations in patients with fibrosing interstitial lung diseases

This study aimed to assess the potential of home monitoring using a monitoring application for the early prediction of acute exacerbations (AEs) in patients with fibrosing interstitial lung diseases (F-ILDs) by tracking symptoms, peripheral blood oxygen saturation (SpO2), and heart rate (HR). Data on symptoms, SpO2, and HR before and after a 1-min sit-to-stand test (1STST) were collected using an online home monitoring application. Symptoms were recorded at least 3 times a week, including cough intensity and frequency (Cough Assessment Test scale (COAT) score), breathlessness grade (modified Medical Research Council (mMRC) score), and SpO2 and HR before and after 1STST. Eighty-five patients with stable F-ILDs were enrolled. We observed a significant increase in COAT and mMRC scores, alongside a significant decrease in SpO2 before and after 1STST, 2 weeks before the first recorded AE. Furthermore, a combination of variables-an increase in COAT (≥ 4) and mMRC(≥ 1) scores, a decrease in SpO2 at rest (≥ 5%), and a decrease in SpO2 after 1STST (≥ 4%)- proved the most effective in predicting AE onset in patients with F-ILDs at 2 weeks before the first recorded AE. Home telemonitoring of symptoms, SpO2 holds potential value for early AE detection in patients with F-ILDs.

Acute Sleep Deprivation and Cerebral and Skeletal Muscle Oxygenation: A Review and Future Directions

Cerebral and skeletal muscle oxygenation are critical research areas for understanding blood flow and oxygen delivery during various physiological states, including cognitive tasks and exercise. Measuring oxygenated and deoxygenated hemoglobin through functional near-infrared spectrometry (fNIRS) enables non-invasive assessment of cerebral and skeletal muscle oxygenation. Research using fNIRS to explore oxygenation after sleep deprivation (SD) is limited and often contradictory. We reviewed how SD affects cerebral and muscle oxygenation as part of a broader review of how SD affects exercise through altered physiologic and perceptual responses. Herein, we consolidate existing knowledge, identify gaps, and suggest directions for future investigation. A comprehensive literature review was conducted via predefined search parameters using PubMed and Google Scholar, focusing on studies that employed fNIRS to measure cerebral and/or skeletal muscle oxygenation in humans after SD (total or partial) or in individuals with chronically fragmented sleep due to obstructive sleep apnea (OSA). Select studies report increased cerebral oxygenation post-SD, potentially due to compensatory mechanisms and increased brain activity. Contrarily, several studies indicate decreased cerebral oxygenation following SD, potentially due to impaired endothelial function, cortical neurovascular coupling, suppressed brain activity, or decreased oxygen consumption. Cerebral oxygenation may be associated with perceived exertion, suggesting meaningful links to exercise. Interestingly, exercise training may mitigate the effects of SD on oxygenation. The only study investigating skeletal muscle oxygenation with regards to sleep status found a lower tissue saturation index in OSA participants compared to controls, though hemoglobin parameters did not differ. The effect of SD on oxygenation remains equivocal, with no studies fully elucidating the mechanisms underlying these changes. This review is the foundation for an ongoing prospective study investigating the impact of acute SD on exercise capacity and fNIRS-derived cerebral and skeletal muscle oxygenation, with two participants enrolled to date and interim analyses planned at n=5 participants.