Dissolved Oxygen Research Articles

Exploring the Lifeline: Unpacking the Complexities of Placental Vascular Function in Normal and Preeclamptic Pregnancies.

The proper development and function of the placenta are essential for the success of pregnancy and the well-being of both the fetus and the mother. Placental vascular function facilitates efficient fetal development during pregnancy by ensuring adequate gas exchange with low vascular resistance. This review focuses on how placental vascular function can be compromised in the pregnancy pathology preeclampsia, and conversely, how placental vascular dysfunction might contribute to this condition. While the maternal endothelium is widely recognized as a key focus in preeclampsia research, this review emphasizes the importance of understanding how this condition affects the development and function of the fetal placental vasculature. The placental vascular bed, consisting of microvasculature and macrovasculature, is discussed in detail, as well as structural and functional changes associated with preeclampsia. The complexity of placental vascular reactivity and function, its mediators, its impact on placental exchange and blood distribution, and how these factors are most affected in early-onset preeclampsia are further explored. These factors include foremost lipoproteins and their cargo, oxygen levels and oxidative stress, biomechanics, and shear stress. Challenges in studying placental pathophysiology are discussed, highlighting the necessity of innovative research methodologies, including ex vivo experiments, in vivo imaging tools, and computational modeling. Finally, an outlook on the potential of drug interventions targeting the placental endothelium to improve placental vascular function in preeclampsia is provided. Overall, this review highlights the need for further research and the development of models and tools to better understand and address the challenges posed by preeclampsia and its effects on placental vascular function to improve short- and long-term outcomes for the offspring of preeclamptic pregnancies. © 2024 American Physiological Society. Compr Physiol 14:5763-5787, 2024.

Efficient Screening in Obstructive Sleep Apnea Using Sequential Machine Learning Models, Questionnaires, and Pulse Oximetry Signals: Mixed Methods Study.

Obstructive sleep apnea (OSA) is a prevalent sleep disorder characterized by frequent pauses or shallow breathing during sleep. Polysomnography, the gold standard for OSA assessment, is time consuming and labor intensive, thus limiting diagnostic efficiency. This study aims to develop 2 sequential machine learning models to efficiently screen and differentiate OSA. We used 2 datasets comprising 8444 cases from the Sleep Heart Health Study (SHHS) and 1229 cases from Taipei Veterans General Hospital (TVGH). The Questionnaire Model (Model-Questionnaire) was designed to distinguish OSA from primary insomnia using demographic information and Pittsburgh Sleep Quality Index questionnaires, while the Saturation Model (Model-Saturation) categorized OSA severity based on multiple blood oxygen saturation parameters. The performance of the sequential machine learning models in screening and assessing the severity of OSA was evaluated using an independent test set derived from TVGH. The Model-Questionnaire achieved an F1-score of 0.86, incorporating demographic data and the Pittsburgh Sleep Quality Index. Model-Saturation training by the SHHS dataset displayed an F1-score of 0.82 when using the power spectrum of blood oxygen saturation signals and reached the highest F1-score of 0.85 when considering all saturation-related parameters. Model-saturation training by the TVGH dataset displayed an F1-score of 0.82. The independent test set showed stable results for Model-Questionnaire and Model-Saturation training by the TVGH dataset, but with a slightly decreased F1-score (0.78) in Model-Saturation training by the SHHS dataset. Despite reduced model accuracy across different datasets, precision remained at 0.89 for screening moderate to severe OSA. Although a composite model using multiple saturation parameters exhibits higher accuracy, optimizing this model by identifying key factors is essential. Both models demonstrated adequate at-home screening capabilities for sleep disorders, particularly for patients unsuitable for in-laboratory sleep studies.

High-flow nasal cannula oxygen therapy versus conventional oxygen therapy in patients undergoing bronchoscopy: a retrospective study

BackgroundPatients undergoing bronchoscopy, particularly those with pre-existing hypoxemia, face a significant risk of further deterioration in their oxygen saturation levels. This heightened risk necessitates the provision of supplemental oxygen therapy throughout the procedure, rendering it mandatory. High-flow nasal cannula (HFNC) has been widely employed in the management of hypoxemic acute respiratory failure (ARF) in adults. Based on this, HFNC has been used in endoscopic procedures, but there are still few studies on HFNC in fiberoptic bronchoscopy (FOB) patients. The purpose of this study was to evaluate the comparative efficacy of HFNC with nasal cannula oxygen in maintaining adequate oxygen saturation during fiberoptic bronchoscopy in patients with pre-existing hypoxemia.MethodsWe retrospectively investigated 232 patients with hypoxemia who underwent bronchoscopy between January 2018 to August 2023 who received either HFNC or nasal cannula oxygen supplementation. The control group received nasal cannula oxygen, and the observation group received HFNC. The changes of oxygen saturation, heart rate, blood pressure and adverse events during the operation were compared between the two groups.ResultsThe patients were divided into the HFNC (n = 78) and nasal cannula oxygen (n = 154) groups. During FOB, although the lowest oxygen saturation (SpO2) was similar in both groups (intraoperative minimum SpO2 was defined as the lowest value of SpO2 occurring between the start of anesthesia and the end of the operation), the occurrence of the lowest SpO2 < 90% was significantly lower in the HFNC group (3.8% vs. 17.5%, p = 0.003). No serious complications were reported in either group, however, the overall incidence of general adverse events was 7.7% and 20.1% in the HFNC and conventional oxygen therapy (COT) groups, respectively (p = 0.015). Multifactorial analysis showed that higher arterial partial pressure of oxygen versus the fraction of inspired oxygen (PaO2/FiO2; P/F) was a protective factor against desaturation events (p = 0.032, OR = 0.990, 95% CI: 0.982–0.999). In patients with baseline PaO2/FiO2 ≥ 200 mmHg, the HFNC group exhibited smoother vital sign changes from pre-procedure to the end of bronchoscopy, although there were no significant differences between the two groups regarding the rates of deoxygenation events as well as adverse events.ConclusionThe use of HFNC therapy can effectively reduce the incidence of SpO2 < 90% during bronchoscopy in patients with hypoxemia. Additionally, HFNC significantly reduces the overall incidence of adverse events compared to COT. In patients with milder hypoxemia, its advantages in maintaining operational stability during bronchoscopy should not be overlooked.

Physiological monitoring to prevent diving disorders

Insight into human physiology is key to maintaining diver safety in underwater operational environments. Numerous hazardous physiological phenomena can occur during the descent, the time at depth, the ascent, and the hours after a dive that can have enduring consequences. While safety measures and strict adherence to dive protocols make these events uncommon, diving disorders still occur, often with insufficient understanding of the factors that triggered the event. This review first examines the most common diving disorders and their incidence rates across recreational and US military dive activities. The review then identifies physiological biomarkers (e.g., heart rate, heart rate variability, blood pressure, respiration rate, temperature, oxygen saturation) that may provide a holistic view of the diver’s current physiological state and potentially detect the most concerning diving disorders (e.g., decompression illnesses, gas mixture-related disorders, barotraumas, and environment exposure). Although considerable research is still needed to verify the use of these biometrics in the diving environment, the research described in this review presents a promising path to developing a system that can detect pending diving disorders and provide divers and other necessary parties with an early warning before mishaps occur.

Clinical Characteristics and Prognosis in Allergic Health Workers Patients with COVID-19 Infection

Background: After a case of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was reported in Wuhan, China, at the end of 2019, the cause of coronavirus disease 2019 (COVID-19) was soon recognized as a global public health emergency. Objectives: This study aimed to investigate the clinical characteristics of allergic healthcare workers (HCWs) confirmed to have COVID-19. Methods: This study included 30 HCWs with confirmed COVID-19 at Kosar Hospital in Semnan, Iran, from February to June 2020 (15 allergic and 15 non-allergic individuals). Demographic data, clinical manifestations, and laboratory findings of the subjects were recorded. Results: Total IgE, allergen-specific IgE, and anti-SARS-CoV IgG were measured in the patients' serum. The average age of the allergic and non-allergic HCWs with COVID-19 was 33 years, and 80% were female. Malaise (76.6%), fever (60%), weakness (60%), and dry cough (56.7%) were the most common symptoms. The clinical findings showed a significantly lower percentage (33.3%) of dry cough in subjects with allergic diseases. Apart from the observed difference in the mean value of total IgE between the two groups, no significant differences were found with respect to age, duration of disease, O2 saturation, and anti-SARS-CoV-2 IgG. Conclusions: Coronavirus disease 2019 symptoms did not become severe in patients with atopic diseases. Moreover, dry cough and weakness were reported by a lower percentage of allergic HCWs.

IMPACT OF NOCTURNAL OXYGEN ENRICHMENT ON HIGH-ALTITUDE ACCLIMATIZATION.

Nocturnal oxygen enrichment improves sleep at high-altitude but may impair acclimatization. PURPOSE: Determine if nocturnal oxygen enrichment impacts acclimatization. METHODS: A 7-day acclimatization protocol occurred at a field-based research site between 0-4200m. Participants were housed at 2800m and slept with (O2+, 32.3±2.5% O2) or without (O2-, 20.8±0.1% O2) nocturnal oxygen enrichment. Resting and steady-state cycling (5-min, 1.75 W·kg-1) tests occurred on Day 0 (0m) and Days 1, 4, and 7 (2800m). Sleep, <em>vastus lateralis</em> muscle oxygenation (oxygenated hemoglobin [O2Hb], deoxygenated hemoglobin [HHb]), arterial blood oxygen saturation (SPO2), heart rate (HR), and expired gases were measured. Five daily hikes from 2800-4200m were also completed. RESULTS: Sleep was longer (p=0.028) and overnight SPO2 higher (p<0.001) in the O2+ (452±63 min, 96±1%) than the O2- group (427±63 min, 91±2%). The O2+ and O2- groups did not differ at rest in ∆O2Hb (-1.47±0.99, -1.46±1.30 A.U., p=0.901), ∆HHb (0.78±0.84, 0.51±0.96 A.U., p=0.202), SPO2 (93±3, 93±3%, p=1.000), HR (59±6, 64±13 beats·minute-1, p=0.229), respiratory exchange ratio (RER, 0.81±0.07, 0.79±0.06, p=0.274), and ventilation BTPS (10.56±2.12, 10.80±1.96 L·minute-1, p=0.717). The O2+ and O2- groups also did not differ while cycling in ∆O2Hb (-2.96±3.03, -1.70±3.46 A.U., p=0.278), ∆HHb (7.59±4.65, 6.34±3.21 A.U., p=0.451), SPO2 (90±6, 89±6%, p=0.875), HR (113±10, 118±16 beats·minute-1, p=0.408), RER (0.89±0.06, 0.89±0.07, p=0.756), and ventilation BTPS (54.00±15.42, 60.18±18.42 L·minute-1, p=0.371). SPO2 while cycling returned towards Day 0 (0m) values by Day 7 (2800m) in both groups (p<0.001) indicating short-term acclimatization. CONCLUSION: Nocturnal oxygen enrichment improves sleep but does not impair short-term acclimatization when completing daily prolonged exercise.

Clinical study of two mandibular advancement devices in the treatment of Obstructive Sleep Apnea: a pilot randomized controlled trial

ObjectiveA preliminary clinical evaluation of the efficacy, comfort, and adverse reactions of two mandibular advancement devices (MADs) in the treatment of Obstructive Sleep Apnea (OSA).MethodsForty patients with mild-to-severe OSA were recruited and randomly divided into two groups. They were treated with Shark-fin or Silensor MAD, respectively. Treatment efficacy was evaluated by home sleep apnea tests, the snoring scale, Epworth Sleepiness Scale (ESS) and the Pittsburgh Sleep Quality Index (PSQI). A comfort scale questionnaire was applied. Cone beam computed tomography (CBCT), cephalometric radiography, and intraoral scanning were made before and after 3-month treatment to detect temporomandibular joints (TMJ), dental and skeletal changes. All data were assessed as normal distributed and analyzed by t test. The significance level was defined as α = 0.05.ResultsThe effective rate, defined as a decrease in Respiratory Event Index (REI) to less than 5 events per hour or a decrease of more than 50%, was 70% in the Shark-fin MAD group and 50% in the Silensor MAD group. REI, lowest oxygen saturation and maximum apnea and hypoventilation time were significantly improved in Shark-fin MAD group (P < 0.01), and the proportion of non-rapid eye movement (REM) sleep stage 3 was higher than before use (P < 0.05), while only REI and lowest oxygen saturation were significantly improved in Silensor MAD group (P < 0.05). The loudness of snoring was significantly decreased after one day using Shark-fin MAD (P < 0.05), and further decreased after one month (P < 0.01). Conversely, Silensor MAD exhibited inferior efficacy in mitigating snoring compared to Shark-fin MAD. Upon wearing the Shark-fin MAD, ESS were significantly improved after one month and three months (P < 0.05), and PSQI improved after three months (P < 0.05). Additionally, the Shark-fin MAD group had a significantly better comfort score compared to the Silensor MAD group (P < 0.05). There was no significant difference in TMJ, dental and skeletal structures in the two groups before and after treatment (P > 0.05).ConclusionBoth two MADs were effective in reducing REI and increasing lowest oxygen saturation on OSA patients, and Shark-fin MAD has better improvement effect and faster onset of action. In addition, Shark-fin MAD was superior to Silensor MAD in improving snoring loudness, daytime sleepiness, sleep quality and wearing comfort. There were no significant dental or skeletal changes, and no alterations in occlusion or temporomandibular joint function in the short term.Trial registrationClinical Trials.gov Registration ID ChiCTR2400086628. Registered 08/07/ 2024-Retrospectively registered, https://register.clinicaltrials.gov.

Light-guided dynamic phantom to mimic microvasculature for biomedical applications: an exploration for pulse oximeter.

Dynamic phantoms capable of changing optical properties by control are essential for standardizing and calibrating spectroscopy systems such as the pulse oximeter. However, current liquid dynamic phantoms containing human blood have a short shelf life and require complex experimental setups. Some solid dynamic phantoms are influenced by the angular-dependent performance of the liquid crystal display (LCD), some have a low spatial resolution, and some have slow control of optical properties. We aimed to develop a solid dynamic phantom, which can overcome these obstacles by changing the optical properties rapidly and generating dynamic biological signals. The absorption properties of the phantom can be controlled in real time by modulating an LCD. A light guide was employed to avoid the angular-dependent performance of the LCD by isolating the scattering top-layer tissue-mimicking silicone phantom from the LCD. The dynamic phantom was characterized at 940, 660, 530, and 455nm to create a lookup table. Photoplethysmography signals of different heart rates from 80 to 120 beats per minute were synthesized, and oxygen saturation levels at 86%, 90%, 95%, and 100% were generated at multiple wavelengths. The design, characterization, and potential applications of the dynamic phantom have been presented. This dynamic phantom can simulate various biological signals by applying corresponding modulation signals and has the potential to calibrate and validate pulse oximeter, imaging, and spectroscopy systems.

Evaluating the feasibility of using whole blood gene expression profiles to identify novel targets in canine septic peritonitis.

To assess gene expression profiles in canine whole blood with and without septic peritonitis to assess workflow feasibility and identify potential blood biomarkers that could be further investigated in future studies. This study enrolled 6 dogs with cytologically confirmed septic peritonitis of any cause and 6 healthy dogs. All dogs had a CBC and biochemistry performed. The dogs with septic peritonitis also had point-of-care lactate and blood oxygen saturation measured for acute patient physiologic and laboratory evaluation score calculation. All dogs then had 2.5 mL of whole blood collected and placed into an RNA stabilization tube, which was processed using a commercial assay based on the hybridization of fluorescent probes for transcript quantification. Quality control, normalization, and data visualization were performed. Raw counts were exported, and differential expression was performed. The evaluation of canine whole blood expression profiles was confirmed to be feasible. Differential expression analysis of septic and nonseptic dogs demonstrated distinct gene expression profile signatures. Five genes of interest were upregulated in septic whole blood including matrix metallopeptidase 9, IL-1 receptor type 2, proliferating cell nuclear antigen, phosphatidylinositol 3-kinase catalytic-γ, and cluster of differentiation 55. The study and associated workflow were feasible and can be scaled in confirmatory studies. Future studies are now proposed to further validate the increased expression of putative biomarkers in a larger cohort of canine septic peritonitis patients with more relevant comparator control cohorts.

Effectiveness of Manual Bronchial Clearance Techniques in the Treatment of Bronchiolitis

Background: Bronchiolitis is a seasonal viral infection of the respiratory tract that causes numerous childhood hospitalizations annually. Treatments vary based on severity, with mild cases requiring fluids and moderate to severe cases involving hospitalization with oxygen therapy, bronchodilators, and chest physiotherapy. Manual bronchial clearance techniques differ between Anglo-Saxon and European schools, and their effectiveness remains a subject of debate. Objective: The aim of this systematic review is to evaluate the effectiveness of manual bronchial clearance techniques in bronchiolitis by assessing clinical outcomes, including improved ventilation, increased oxygen saturation, and enhanced hemodynamic and respiratory stability. Materials and Methods: A systematic review was conducted between 2013 and 2024 using PRISMA guidelines. Databases searched included PubMed, Science Direct, Scopus, Springer, and Google Scholar; the inclusion criteria focused on randomized clinical trials and cohort studies in English, Spanish, and Portuguese. The selection bias was evaluated. The study was registered in Prospero (CRD42023486450). Results: Five articles involving 291 participants diagnosed with mild to moderate bronchiolitis were analyzed. The assessed techniques included Anglo-Saxon school and European School. Heart rate was evaluated in four studies, showing significant reductions in one (p &lt; 0.01), while the significance in the other studies was not specified. Respiratory rate was assessed in three studies, with significant results being seen in two (p &lt; 0.05). SpO2 was examined in all six studies, demonstrating significant improvements in two (p = 0.02 and p &lt; 0.05). The Kristjansson respiratory score showed significant changes in one study (p = 0.005), and the Wang respiratory score indicated significant results in another (p = 0.03). These findings support the efficacy of chest physiotherapy techniques in managing bronchiolitis. Conclusions: While Anglo-Saxon techniques are widely used, their effectiveness remains a subject of debate. In contrast, European techniques indicate promising clinical outcomes, including improved ventilation, increased oxygen saturation, and enhanced respiratory stability; however, additional studies could further validate these findings.

A finer-grained high altitude EEG dataset for hypoxia levels assessment

The study reports on a high-altitude EEG dataset comprising 64-channel EEG signals from 23 subjects, aiming at achieving a finer-grained assessment of hypoxia levels. Four hypoxia levels were induced by creating a gradient of oxygen partial pressure through changes in altitude and external hypoxia stimulation. The dataset was collected in a hypoxic chamber that simulates altitude changes, allowing for a refined classification of different hypoxia levels based on ranges of oxygen saturation. The total recorded EEG data amounts to approximately 10.25 hours. Validation results indicate that the four hypoxia levels can be effectively recognized using EEG signals. Compared to binary classification, our fine-grained dataset allows for more precise detection of hypoxia levels. This dataset is anticipated to have significant research and practical value in developing accurate methods for identifying hypoxia levels. As a valuable and standardized resource, it will enable extensive analysis and comparison for researchers in the field of high-altitude hypoxia.

The extracellular CIRP as a predictive marker for the endothelial dysfunction in chronic obstructive pulmonary disease combined with pulmonary hypertension

BackgroundPulmonary hypertension (PH) is a serious complication of chronic obstructive pulmonary disease (COPD), distinguished by pulmonary endothelial dysfunction. The extracellular cold-inducible RNA-binding protein (eCIRP) is a damage-associated molecular pattern (DAMP) that triggers inflammation and causes vascular endothelial dysfunction in COPD-PH.MethodsThe expression levels of CIRP were compared in peripheral lung tissues among 40 individuals. Moreover, A prospective analysis was conducted on serum levels of eCIRP, interleukin (IL) 1β, IL-33, endothelin-1 (ET-1), and nitric oxide (NO) in 150 COPD patients and 50 healthy control individuals at Jiangsu Taizhou Peoples Hospital. The study aimed to compare these serum levels and correlations among COPD-PH group, COPD non-PH group and the normal group.ResultsWe found higher CIRP levels in COPD-PH compared to COPD non-PH and the normal in lung tissue samples. A prospective analysis showed higher serum levels of eCIRP, IL-1β, IL-33, and ET 1 in COPD-PH, while a noticeable reduction in NO levels. There exists a correlation between the severity of COPD-PH and elevated levels of eCIRP, proinflammatory cytokines like IL-1β and IL-33, along with indicators of endothelial dysfunction like endothelin-1 ET-1 and NO. Moreover, the serum eCIRP level demonstrated a notable positive correlation with the levels of IL-1β, IL-33, PCT, and ET-1, while displaying a negative correlation with NO and Peripheral Oxygen Saturation (SpO2). Moreover, the serum eCIRP level demonstrated a notable positive correlation with the levels of IL-1β, IL-33, PCT, and ET-1, while displaying a negative correlation with NO and SpO2. Moreover, an assessment of independent risk factors for COPD-PH with ROC curve analysis, gauged the predictive value of serum eCIRP, IL-1β, IL-33, ET-1, and NO levels in diagnosing COPD-PH. Elevated eCIRP, IL-33, and ET-1 levels significantly correlated with COPD-PH, highlighting eCIRP’s strong predictive value for this condition.ConclusioneCIRP levels could serve as a valuable biomarker for predicting endothelial dysfunction in COPD-PH.

Oxygenation of the Gulf of Mexico thermocline linked to the detachment of Loop Current eddies

This study presents oxygen data from the Gulf of Mexico (GoM) deep-water region for the period 2010–2019 collected from six oceanographic cruises and two BioARGO buoys and compares them to historical measurements. These observations link the interannual variability of the oxygen concentrations in the main thermocline waters to the frequency of Loop Current eddy (LCE) detachments. These eddies introduce significant volumes of relatively oxygen-rich waters from the Caribbean into the Gulf’s interior, thereby ventilating the main thermocline waters of the basin. Oxygen concentrations [O2] observed after periods of more than a year without LCE detachments consistently show a significant decrease in [O2] in the GoM thermocline waters. Using the oxygen measurements and altimetry data, we developed a simple box model that reproduces the oxygen variability in the GoM thermocline considering only LCE detachment area and frequency as variables, keeping all other sources of variability constant in the model. Our model successfully reproduces the observed oxygen variability in the main thermocline waters, highlighting the LCE detachment variability as a key process in the ventilation of the GoM mid-depth waters. According to our model, an average detached LCE area of approximately 97,000 km2 per year is needed to maintain oxygen levels in the thermocline waters above 2.6 ml mL L−1 in the upper thermocline and 2.4 ml mL L−1 in the lower thermocline. One further implication of this model is that if the yearly trend of decreasing detachment area of the LCEs continues in future years, oxygen concentrations in the GoM thermocline may continue to fall, potentially leading to unknown consequences for the ecological web structure at these depths.

Changes in the Content of microRNA775a and its Role in Post-Transcriptional Regulation of Targeted Genes in Corn Leaves under Hypoxia

Under the influence of hypoxia in the plant organism, the transcription of genes responsible for adaptation to stress caused by low oxygen levels changes. Changes in metabolic pathways under stress conditions may be regulated by microRNAs. It was found that the content of microRNA775A increases in corn leaves under the influence of hypoxia. The use of the fluorescent probe miR775A-ROX made it possible to establish an increase in the number of RNA-inducing silencing complexes (RISC), formed on the basis of microRNA775A, in maize leaves during the development of hypoxic stress. The results obtained indicate that microRNA775A is involved in the processes of adaptation of the body to hypoxic conditions by regulating the expression of target genes at the post-transcriptional level using the RNA interference mechanism.

Transferability of Exercise Intensity Based on Muscle Oxygenation from Normoxia to Hypoxia in Ski-Mountaineering Athletes—Exploratory Study

Frequent changes in altitude and oxygen levels limit the practical application of traditionally derived exercise thresholds or training zones based on heart rate (HR) or blood lactate concentration (bLa). We investigated the transferability of a muscle oxygenation (SmO2)-based intensity prescription between different hypoxic conditions to assess the suitability of real-time SmO2 measurements for ski-mountaineering (SKIMO) athletes during submaximal endurance exercise. A group of 15 well-trained male SKIMO athletes performed a graded-intensity run test in normoxia (87 m ASL, FiO2 = 20.8%) to determine the anaerobic threshold (AnT) with the mod-Dmax method, and maximal lactate steady state (MLSS) assessments in acute normobaric hypoxia (3000 m ASL, FiO2 = 14.4%) with the intensity aligned to 90–105% of SmO2 at the normoxia-determined AnT. SmO2, HR, and bLa were monitored during both tests. The number of MLSS assessments without a bLa increase over 1 mmol·L⁻1 was reported. Paired t-tests with Cohen’s d effect sizes and intraclass correlation coefficient (ICC) were computed to compare the bLa and HR at the AnT in normoxia and MLSS averages in hypoxia, as both corresponded to equivalent SmO2. Out of the 15 MLSS assessments, 11 (73.3%) were performed without a bLa increase over 1 mmol·L⁻1. Significant differences at equivalent SmO2 in normoxia and hypoxia were found for HR (175 ± 11.7 vs. 160 ± 14.2 bpm, p = 0.005, d = 1.02), but not for bLa (4.9 ± 1.2 vs. 5.1 ± 2.4 mmol·L⁻1, p = 0.845, d = −0.05). ICC(2,k) for HR and bLa were 0.56 (95% CI: −0.24, 0.85) and 0.40 (95% CI: −0.75, 0.80), respectively. The results indicate a fair transferability of a SmO2-based intensity prescription between different hypoxic conditions in well-trained SKIMO athletes during submaximal endurance exercise. The practical significance of the observations depends on the required accuracy of the exercise intensity determination.

Biological growth properties of marine Enteromorpha-diatom and its adhesion evolution on mortar surfaces

Currently, most research on bio-corroded mortar focuses on cyanobacteria and microorganisms in the marine environment, but the specific mechanism of mortar performance at different stages of the specific biological system of marine dominant algae, Enteromorpha-diatom, is still lacking. Therefore, this paper investigates the growth characteristics of Enteromorpha-diatom proliferation organisms and their attachment evolution on mortar. First, the concentration of Enteromorpha spores over 0 to 15 days was studied. Subsequently, the effects of Enteromorpha-diatom on the properties of mortar at different growth stages over 0 to 360 days were investigated through changes in pH, DO (dissolved oxygen), microstructure, mineral composition, and microstructure in the culture medium. The results showed that Enteromorpha-diatom organisms significantly affected the pH and DO in water through photosynthesis and metabolic activities. Additionally, the adhesion of Enteromorpha-diatom organisms significantly impacted the mechanical properties of mortar, with compressive strength decreasing by 46.1% and flexural strength decreasing by 39.0% over 0 to 360 days. Furthermore, the formation of biofilm, deposition of CaCO3, and accumulation of organic and inorganic substances altered the microstructure of mortar, changing its electrochemical characteristics. The electric flux change rate was 46.1%, and the internal impedance decreased by 59% over 0 to 360 days.

High velocity nasal insufflation vs non-invasive positive pressure ventilation in the management of acute hypercapnic respiratory failure

ABSTRACT Introduction High-velocity nasal insufflation (HVNI) is a type of high-flow nasal cannula that depends on the dead-space clearance. HVNI utilizes small-bore nasal cannulae resulting in high velocity flow greater than the flow of the wider bore cannulae that were previously in use. Aim Assess the efficacy of high-velocity nasal insufflation in managing acute hypercapnic respiratory failure and compare between high-velocity nasal insufflations and noninvasive positive pressure ventilation (NIPPV) regarding efficacy and outcome in managing acute hypercapnic respiratory failure. Patients and Methods Over 12 months 48 patients admitted with a diagnosis of acute hypercapnic respiratory failure were enrolled in the study. Twenty-four patients were managed with HVNI, and the other 24 patients were managed with non-invasive ventilation. Patients were closely monitored in the respiratory intensive care unit (RICU). Oxygen saturation, respiratory rate, and Arterial Blood Gases (ABG) were measured before the start of treatment, then 1 hour, 4 hours, 2 days, and 3 days after treatment. Patients were allowed to crossover to the other arm of treatment or endotracheal intubation according to the clinical situation. Results pH, P Co2 levels showed similar changes in the two studied groups and improved with time. Treatment failure and mortality rates were also comparable in the two groups. Failure of treatment occurred in 16% in the group managed with HIVNI and in 33% in the group managed with NIPPV. Intubation at the end of 72 hourswas 16.7% in the group managed with HVNI and 25% in the group managed with NIPPV. Conclusion High velocity nasal insufflation is effective in managing acute hypercapnic respiratory failure. HVNI offers an effective way alternative to NIPPV in managing acute hypercapnic respiratory failure.

The effect of body position on cardiovascular, skeletal muscle and ventilatory responses to submaximal cycling.

The completion of exercise in different body positions can impact the function of various components of the oxygen delivery pathway; however, the effect of the haemodynamic conditions induced by a semi-upright body position on the integrative physiological response to exercise is poorly understood. The purpose of this study was to explore the effect of a semi-upright body position on cardiac output (CO), vastus lateralis oxygen saturation ( ), oxygen consumption ( ) and ratings of perceived exertion (Borg RPE) during submaximal cycling. Twenty healthy individuals (22±3 years, 50% female) each completed alternating 5-min bouts of submaximal upright and semi-upright (40° incline) cycling at 50 and 100W. CO, , and RPE were assessed at rest and at each exercise intensity during steady state. There was a main effect of intensity on the increase in CO, , and RPE (all P<0.001). In a semi-upright position, the increase in CO (7.9±2.8vs. 6.4±2.6L/min, P<0.001), RPE (median (interquartile range): 11 (9-13)vs. 10 (8-12), P=0.013) and the decrease in (-38±23vs. -21%±18%, P<0.001) were greater than upright, while the increase in was attenuated (1.030±0.130vs. 1.154±0.165L/min, P<0.001). These results suggest that while a semi-upright body position produces elevations in CO, these elevations do not seem to perfuse the active skeletal muscle. This may explain the elevation in RPE despite a blunting in the increase in . Further work is required to understand the effects of a semi-upright exercise position on skeletal muscle activation and lower limb blood flow.

Implementation of the Oxygen Saturation Index as a Predictor of Outcome in Prenatally Diagnosed CDH Neonates in the First 24 Hours of Life.

This study aimed to evaluate the Oxygen Saturation Index (OSI) as a noninvasive measure for early postnatal management and outcome prediction in neonates with congenital diaphragmatic hernia (CDH). Additionally, the study analyzed the correlation and predictive ability of OSI, Oxygenation Index (OI), Horovitz Index (HI), and partial pressure of arterial oxygen (PaO2) regarding mortality and the need for extracorporeal membrane oxygenation (ECMO). A retrospective, single-center study using data from 2013 to 2020. Parameters for calculating indices were extracted from patient charts every hour during the first 24 h of life. Statistical analyses included ROC analysis for predictive cut-off values and Spearman's rank for correlation assessments. The study included 138 neonates. Postductal OSI demonstrated high sensitivity (80%-85%) and negative predictive value (NPV) for predicting mortality and ECMO need, with cut-off values between 11.5 and 13. Optimal cut-off values for predicting ECMO need were 10 at 12 and 24 h (sensitivity 96.7%). OSI, OI, HI, and PaO2 showed comparable predictive capabilities with strong correlations. The lowest OI of 18 predicted mortality with a sensitivity of 75% and specificity of 90.9%. Strong correlations were found between the lowest PaO2 and lowest HI (0.963-0.974), and between highest OI and lowest PaO2 (-0.922 to -0.945). OSI is a promising index for predicting outcomes in CDH neonates, showing strong correlation with indices like OI and HI. Despite limitations, OSI provides continuous, bedside monitoring without invasive blood sampling. Further prospective studies are needed to validate these findings and establish new cut-off values.

Effects of red blood cell transfusion on cerebral hemodynamics of preterm neonates.

Anemia is a common problem in preterm neonates, and red blood cell transfusion (RBCT) is used to improve oxygen delivery. However, RBCT is associated with complications, although an increase in cerebral oxygenation has been documented, and no universally accepted biomarker for the need for transfusion (i.e., the concentration of hemoglobin in the blood) has been defined. We used a hybrid optical device (BabyLux device) that merges time-domain near-infrared spectroscopy (TD-NIRS) and diffuse correlation spectroscopy (DCS) to potentially obtain a better assessment of the cerebral effects of RBCT compared with previous studies using continuous wave (CW) spatially resolved NIRS. Eighteen clinically stable preterm neonates were assessed before and after RBCT by the BabyLux device as five repetitions of 60s measurement (with 1s acquisition time), estimating the cerebral blood flow (CBF) as a blood flow index (BFI), the total hemoglobin concentration (tHb), and the cerebral tissue oxygen saturation ( ). was also continuously monitored by a commercial CW-NIRS device, as well as peripheral saturation, . Tissue oxygen extraction (TOE) and cerebral metabolic rate of oxygen consumption ( ) were computed, and the Wilcoxon signed-rank test for paired data was performed, comparing the data acquired before and after RBCT. The BabyLux data from four neonates did not meet quality criteria and were discarded. After the transfusion, tHb and (measured both with TD-NIRS and CW-NIRS devices) significantly increased, causing a significant decrease in TOE. CW-NIRS showed a wider dispersion of data compared with TD-NIRS. However, CBF did not decrease proportionally but the variation was high, as well as for . The results confirm previous CW-NIRS studies, but the wide variability of BFI makes the effects of RBCT on cerebral metabolism uncertain.