Changes In Pressure Research Articles

The Impact of Increased PEEP on Hemodynamics, Respiratory Mechanics, and Oxygenation in Pediatric ARDS.

PEEP is a cornerstone treatment for children with pediatric ARDS. Unfortunately, its titration is often performed solely by evaluating oxygen saturation, which can lead to inadequate PEEP level settings and consequent adverse effects. This study aimed to assess the impact of increasing PEEP on hemodynamics, respiratory system mechanics, and oxygenation in children with ARDS. Children receiving mechanical ventilation and on pressure-controlled volume-guaranteed mode were prospectively assessed for inclusion. PEEP was sequentially changed to 5, 12, 10, 8 cm H2O, and again to 5 cm H2O. After 10 min at each PEEP level, hemodynamic, ventilatory, and oxygenation variables were collected. A total of 31 subjects were included, with median age and weight of 6 months and 6.3 kg, respectively. The main reasons for pediatric ICU admission were respiratory failure caused by acute viral bronchiolitis (45%) and community-acquired pneumonia (32%). Most subjects had mild or moderate ARDS (45% and 42%, respectively), with a median (interquartile range) oxygenation index of 8.4 (5.8-12.7). Oxygen saturation improved significantly when PEEP was increased. However, although no significant changes in blood pressure were observed, the median cardiac index at PEEP of 12 cm H2O was significantly lower than that observed at any other PEEP level (P = .001). Fourteen participants (45%) experienced a reduction in cardiac index of > 10% when PEEP was increased to 12 cm H2O. Also, the estimated oxygen delivery was significantly lower, at 12 cm H2O PEEP. Finally, respiratory system compliance significantly reduced when PEEP was increased. At a PEEP of 12 cm H2O, static compliance had a median reduction of 25% in relation to the initial assessment (PEEP of 5 cm H2O). Although it may improve arterial oxygen saturation, inappropriately high PEEP levels may reduce cardiac output, oxygen delivery, and respiratory system compliance in pediatric subjects with ARDS with low potential for lung recruitability.

Effect of caspase inhibitors on hemodynamics and inflammatory factors in ARDS model rats

To study the effects of caspase inhibitors on hemodynamics and inflammatory factors in acute respiratory distress syndrome (ARDS) model rats. Sixty healthy male Wistar rats were randomly divided into three groups, namely, the control group, ARDS group and ARDS + Caspase inhibitor group, with 20 rats in each group. The control group was intraperitoneally injected with 2 mL/kg saline, and the ARDS model group was established by intraperitoneally injecting 4 mg/kg Lipopolysaccharide (LPS), ARDS + Caspase inhibitor group was adminstered 20 mg/kg caspase inhibitor after intraperitoneal LPS injection. Changes in pulmonary arterial pressure (PAP) and mean arterial pressure (MAP) at 6 and 12 h before and after administration were recorded. Moreover, arterial blood gas was evaluated with a blood gas analyzer and changes in the partial pressure of O2 (PaO2), partial pressure of CO2 (PaCO2), partial pressure of O2/fraction of inspired O2 (PaO2/FiO2) were evaluated. In addition, the lung wet/dry weight (W/D) ratio and inflammatory factor levels in lung tissue were determined. Finally, pathological sections were used to determine the pulmonary artery media thickness (MT), MT percentage (MT%), and the degree of muscle vascularization. The pulmonary arterial pressure of rats was determined at several time points. Compared with the control group, the model group had a significantly increased pulmonary arterial pressure at each time point (P < 0.01), and the mean arterial pressure significantly increased at 6 h (P < 0.05). Compared with that of rats in the model group, the pulmonary arterial pressure of rats in drug administration group was significantly reduced at each time point after administration (P < 0.01), and the mean arterial pressure was significantly reduced at 6 h (P < 0.05). The arterial blood gas analysis showed that compared with those in the control group, PaO2, PaCO2 and PaO2/FiO2 in the model group were significantly reduced (P < 0.01), and PaO2, PaCO2 and PaO2/FiO2 were significantly increased after caspase inhibitor treatment (P < 0.05 or 0.01). The levels of the inflammatory mediators tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) in the model group were significantly higher than those in the control group (P < 0.01), and they were significantly decreased after caspase inhibitor treatment (P < 0.01). In the model group, pulmonary artery MT, MT% and the degree of muscle vascularization were significantly increased (P < 0.05 or 0.01), and pulmonary artery MT and the degree of muscle vascularization were significantly reduced after caspase inhibitor treatment (P < 0.05 or 0.01). Apoptosis Repressor with a Caspase Recuitment Domain (ARC) can alleviate the occurrence and development of pulmonary hypertension (PH) by affecting hemodynamics and reducing inflammation.

Intracranial Pressure Thresholds for Cerebral Autoregulation Impairment: Age-Stratified Analysis of Ultra-Low-Frequency Pressure Reactivity Index (UL-PRx) in Traumatic Brain Injury.

The study investigated the effectiveness of low-frequency sampling in detecting alterations in cerebrovascular reactivity (CVR) associated with changes in intracranial pressure (ICP) in patients with traumatic brain injury (TBI) across different age groups. The primary objective was to investigate an ICP threshold that indicates a decrease in CVR as evidenced by a significant increase in the ultra-low-frequency pressure reactivity index (UL-PRx). Additionally, the study aimed to develop an age-based categorization method for patients with TBI to investigate the differences between these ICP thresholds in different age groups. In this retrospective analysis, data from 263 patients with TBI were prospectively collected. ICP and mean arterial pressure were extracted from the hospital database at 5-min intervals. Demographic details, clinical presentation, computed tomography scans, neurosurgical interventions, and 12-months outcome were recorded. ICP versus UL-PRx values were categorized into ICP bins and graphically represented with boxplots for each age group, illustrating how as ICP values rise, there is a bin (age-tailored ICP [AT-ICP]) beyond which UL-PRx shows a sudden increase, indicating CVR loss. Homogeneous age groups were established to obtain a consistent AT-ICP threshold. The discriminatory ability of the AT-ICP thresholds was compared with the guideline-recommended thresholds by calculating the area under the Receiver Operating Characteristic curve of the ICP-derived indices (dose above threshold, and the hourly dosage above threshold). Age groups 0-5, 6-20, 21-60, 61-70, and 71-85years were the best age subdivisions, corresponding to AT-ICP thresholds of 20, 30, 35, 25, and 30mmHg, respectively. The AT-ICP thresholds exhibited better discriminative ability compared with the guideline-recommended thresholds. The AT-ICP thresholds offer a novel approach for estimating CVR impairment and the developed method represents an alternative solution to address the age stratification issue in patients with TBI.

Impact of Renin-Angiotensin System Blockade on Mortality and Allograft Loss among Renal Transplant Recipients: A Systematic Review and Meta-Analysis.

The blockade of the renin-angiotensin system (RAS) has a beneficial effect on reducing the levels of proteinuria and blood pressure in patients with chronic kidney disease (CKD) and reduces the risk of developing end-stage kidney disease (ESKD) in CKD patients. Nonetheless, a debate persists regarding the impact of RAS inhibitors on outcomes such as mortality and graft survival in renal transplant patients. To assess the effect of RAS inhibitors on graft recipients in the past decade, we conducted a systematic review and meta-analysis. We searched Embase, PubMed, and the Cochrane Central Register of Clinical Trials from January 1, 2012, to August 1, 2022. We included 14 articles, comprising 5 randomized controlled trials (RCTs) and 9 cohort studies, including 45,377 patients. These studies compared patient or graft survival between an RAS inhibitors treatment arm and a control arm. The meta-analysis revealed that RAS blockade was significantly associated with lower mortality in cohort studies (risk ratio [RR] = 0.66, 95% confidence interval [CI]: 0.55-0.79), reduced allograft loss in cohort studies (RR = 0.62, 95% CI: 0.54-0.71), and significant changes in systolic blood pressure in RCTs. Subgroup analysis of the groups of interest (interventions involving RAS blockade, follow-up period of ≥ 5 years) showed consistently reduced mortality (RR = 0.67, 95% CI: 0.56-0.81) and reduced allograft loss (RR = 0.61, 95% CI: 0.54-0.70). Our results demonstrated that the application of RAS blockade among renal transplant recipients was associated with lower mortality and allograft loss in cohort studies but not in RCTs. More powered clinical trials are needed to evaluate the effects of RAS blockade in renal transplant recipients.

Myocardial remodeling in wistar rats with renal dysfunction fed a high-salt diet

BACKGROUND. Dietary adjustment is an important point in the treatment of chronic kidney disease (CKD). However, at present, the effect of a diet with a high NaCl content on the state of the cardiovascular system in patients with early stages of CKD has not been sufficiently studied.The AIM: to evaluate blood pressure levels and changes in the myocardium of Wistar rats with early stage renal dysfunction fed a high-salt diet for a long time.MATERIALS AND METHODS: The study was performed on male Wistar rats. The control group consisted of sham-operated animals (LO-group), receiving a standard diet (0.34 % NaCl), the second – rats subjected to resection of ¾ of the kidney parenchyma, receiving a standard diet (NE-group), the third – rats, subjected to ¾ NE, receiving high sodium diet (4 % NaCl, NE+HSD). After 4 months, the rats were assessed for blood pressure (BP), levels of urea, creatinine, sodium in the blood serum, daily diuresis, albumin content in the urine, myocardial mass index (IMM) and left ventricular myocardial mass index (IMLV), and a histological examination of the myocardium was performed.RESULTS: In rats with kidney dysfunction, an increase in blood pressure was detected, most pronounced in the NE+HSD group. In rats of this group, albumin excretion, connective tissue volume, arterial diameter, thickness of the adventitia and media of myocardial vessels increased relative to the indicators of rats with NE receiving a standard diet. IMLV in NE+HSD rats was higher by 16.4 %, and IMM by 10.9 % than in animals with NE on a standard diet. The groups with NE did not differ from each other in the content of urea and creatinine in the blood serum, although these indicators were higher than in LO animals. There were no differences between groups in serum sodium levels.CONCLUSION: Prolonged consumption of a diet with a high content of table salt contributes to the development of the initial stages of CKD in Wistar rats, promotes blood pressure growth and myocardial remodeling, manifested primarily in the progression of cardiomyocyte hypertrophy and myocardial fibrosis.

Observing and Modeling Short‐Term Changes in Basal Friction During Rain‐Induced Speed‐Ups on an Alpine Glacier

AbstractBasal shear stress on hard‐bedded glaciers results from normal stress against bed roughness, which depends on basal water pressure and cavity size. These quantities are related in a steady state but are expected to behave differently under rapid changes in water input, which may lead to a transient frictional response not captured by existing friction laws. Here, we investigate transient friction using Global Positioning System vertical displacement and horizontal velocity observations, basal water pressure measurements, and cavitation model predictions during rain‐induced speed‐up events at Glacier d'Argentière, French Alps. We observe up to a threefold increase in horizontal surface velocity, spatially migrating at rates consistent with subglacial flow drainage, and associated with surface uplift and increased water pressure. We show that frictional changes are mainly driven by changes in water pressure at nearly constant cavity size. We propose a generalized friction law capable of capturing observations in both the transient and steady‐state regimes.

Simulation study on the dynamic characteristics of natural circulation coupled phase change material for equal height difference passive containment cooling system

The passive containment cooling system (PCCS) plays a significant role in ensuring the safety of nuclear power plants. To further reduce peak pressure in the containment during a loss of coolant accident (LOCA), phase change materials (PCMs) are utilized to improve the system’s cooling effectiveness. The dynamic simulation model of PCCS has been developed using Apros software. This article focuses on examining the system’s dynamic characteristics related to various tube startup methods and comparatively analyzing the impact of different PCM thicknesses on heat transfer capacity. The results indicate that post-accident, PCM significantly suppresses peak pressure in the containment. Under the full tube startup method with 4 mm PCM, the peak pressure decreases to 1.75 MPa, whereas under the empty tube startup method, it is reduced to 1.69 MPa. With natural circulation empty tube startup method, PCM can reduce pressure change intensity in the containment but negatively affects natural circulation heat transfer. Although the full tube startup method underperforms the empty tube startup method on suppressing peak pressure, PCM can positively affect natural circulation heat transfer in the early stages of the accident. Empty tube startup offers the advantages of higher heat transfer capacity and lighter weight, making it the optimal choice for ocean nuclear platforms. Additionally, the higher peak power of PCM heat transfer under the empty tube startup method indicates that system can withstand larger thermal shocks.

The molecular dynamics simulation of coronavirus- based compound (6OHW structure) interaction with interferon beta-1a protein at different temperatures and pressures: Virus destruction process

The Interferon beta-1a protein is a cytokine in the Interferon family that is used to treat a variety of ailments. Molecular Dynamics simulation was used to characterize the atomic disintegration of 6OHW structure of a corona virus-based compound with Interferon beta-1a protein in this computational study. Molecular Dynamics simulation results on the atomic evolution of the 6OHW structure were presented with estimating physical variables. Physically, our simulations showed the attraction forces between the virus and the atomic protein in the presence of H2O molecules, resulting in viral annihilation after t = 10 ns. The molecular dynamics package's initial pressure and temperature (Temp) changes were important for virus-protein system evolution. Numerically, increasing primary T and P from 300 K and 1 bar to 350 K and 5 bar reduced the atomic distance between virus and protein structures from 10 Å to 2.71 Å and 2.45 Å. Bonding energy was another reported physical quantity in our Molecular Dynamics simulation work. The atomic parameter ranged from 152.57 kcal/mol to 148.54 kcal/mol due to changes in initial Temp and pressure. Ultimately, the diffusion coefficient of protein being simulated inside the atomic virus changed from 0.48 μm2/s to 0.59 μm2/s. This calculation demonstrated the suitable conduct of simulated protein throughout virus destruction process.

Pharmacological modulation of intrarenal pressure in a porcine model using a novel isoprenaline-eluting guidewire.

Introduction Several complications of retrograde intrarenal surgery have been attributed to inadvertent increases in intrarenal pressure. We recently described the development of an innovative isoprenaline-eluting guidewire (IsoWire). The objective of this study was to investigate the impact of IsoWire on the intrarenal pressure and evaluate its safety. Materials and Methods This study was performed in 17 renal units using a porcine model. As controls, the intrarenal pressure, heart rate, and mean arterial pressure were measured for a duration of six minutes with a standard guidewire placed in the renal pelvis. For the experiment, the conventional guidewire was substituted with the IsoWire and the same parameters were measured. Blood samples were taken at one-minute intervals to measure plasma isoprenaline levels. This procedure was repeated on the opposite side. Results The mean intrarenal pressure reduction was 29% (95% CI: 13% - 53%). The mean isoprenaline effect time was 174 seconds. No changes in heart rate (p = .908) or mean arterial pressure (p = .749) were recorded after IsoWire insertion. Plasma isoprenaline levels were below the quantitation threshold. Isoprenaline concentrations in the plasma were below the quantification threshold. Ureteroscopy revealed no ureteral lesions. Conclusions The IsoWire demonstrated a safe and effective reduction of intrarenal pressure. Additional research is necessary to determine whether ureteric smooth muscle relaxation generated by isoprenaline facilitates easier insertion of a ureteric access sheath, decreases the incidence of ureteric access sheath related ureteric lesions, or even encourage the practice of sheathless retrograde intrarenal surgery.

Аналіз впливу на прохідність автобронетанкової техніки конструктивних факторів та методика її збільшення шляхом автоматичного регулювання тиску повітря в шинах коліс

The purpose of the study is to analyze and determine the influence of various factors on the patency of armored vehicles (AMT) operated by the National Guard of Ukraine. Determination of the change in patency during the movement of AMT in different road and climatic conditions. Analysis of static and dynamic loads, which are characteristic of AMT movement over rough terrain, and their impact on the efficiency of the vehicle. The theoretical component of the study was carried out using mathematical modeling of the work process of regulating the air pressure in tires of AMT wheels, using the example of changes in the characteristics of adhesion coefficients with the supporting surface and rolling resistance depending on the change in pressure and load on the tires of the wheels when the AMT is moving off-road. As a result of mathematical modeling, the dependences of air pressure in tires of AMT wheels were obtained, depending on the coefficient of rolling resistance and the load on each of the wheels. Which, in turn, makes it possible to move to a sufficiently complete mathematical modeling of the movement of AMT on off-road, taking into account the reference cross-country ability. In the process of theoretical research, the structural parameters of the impact on the patency of AMT were analyzed quite completely, and a generalized comparative indicator of the patency parameters of vehicles was proposed. When analyzing it, it was found that the AMT tire and, specifically, the change in air pressure in it, have a significant impact on the bearing capacity. The authors propose to use the following evaluation criteria as criteria for assessing the efficiency of the passability when driving on deformable surfaces: a generalized comparative indicator of the parameters of the passability of vehicles. As a result of consideration of which, a significant influence on the patency parameters of the tires and directly the air pressure in them was established. Regulation and change of the air pressure in the tires of the wheels depending on the change in the coefficient of rolling resistance as well as the change in the load on each wheel, which are the ratio of the work that is spent on the traction force when overcoming different degrees of heaviness of the resistance of the supporting surfaces with the effect of deformation. And the load that falls on each of the AMT wheels allowed us to draw conclusions about the improvement of the regular tire pressure regulation system (RPRS) of the wheels.

Correlation Between Serum Transaminase Levels and Estimated Glomerular Filtration Rate After Living-Donor Kidney Transplantation

BackgroundThere is a risk of hypoperfusion during kidney transplantation surgery owing to patients’ underlying disease and ischemia-reperfusion injury; further, hypoperfusion may cause injury to major organs. We hypothesized that the decrease in blood pressure after ischemia-reperfusion injury during kidney transplantation may be associated with indicators of liver injury and kidney graft function. MethodsData regarding living-donor kidney transplantations performed at our institution between 2018 and 2022 were retrospectively evaluated. Exclusion criteria included pediatric recipients or donors aged <18 years, multiple organ transplantation, and elevated postoperative serum transaminase levels. Correlations among blood pressure, serum transaminase levels on postoperative days 3 to 5, and estimated glomerular filtration rate (eGFR) on postoperative days 7 and 14 were analyzed. Further, a subgroup analysis was performed based on eGFR. ResultsA total of 276 patients were included in the final analysis. Serum transaminase levels were significantly negatively correlated with eGFR (partial correlation coefficient—0.26, P < .001). The postreperfusion decrease in blood pressure was not correlated with serum transaminase levels. However, the postreperfusion decrease in blood pressure and baseline blood pressure correlated with the eGFR (partial correlation coefficient = −0.18, P = .004). ConclusionThese findings indicate a correlation between intraoperative liver injury and kidney graft function, suggesting the importance of intraoperative management of organ perfusion. Since postreperfusion blood pressure changes did not significantly correlate with liver injury indicators, it is important to consider other causative factors for hypoperfusion in major organs during living-donor kidney transplantation, including microcirculatory failure and organ congestion-related ischemia/reperfusion.

Comparison of General Anesthesia and Spinal Anesthesia on Hemodynamic Stability in Patients Undergoing Hernia Repair

Introduction. The issue of choosing the optimal anesthesia that is least dangerous to the patient’s life is still the main concern of the workers in the anesthesia and intensive care department, including techniques, medications, plans, and instructions followed in order to choose the best anesthesia. It can also be said that spinal anesthesia is the best and most standard anesthesia for those who repair hernia.The aim of the study — learn about obtaining and verifying hemodynamic stability in patients undergoing hernia repair under anesthesia.Materials and methods. An accurate and recent study of patients attending Al-Hussein Medical City and Al-Hassan Hospital in the city of Karbala. We included 100 patients who underwent a herniotomy, were divided into two groups on the types of general and spinal anesthesia. Fifty patients received general anesthesia and 50 patients received spinal anesthesia. Data related to the patient’s age, weight, change in blood pressure and pulse rate were analyzed. The study analyzed patients aged 20–90, dividing them into two groups: general anesthesia (GA) and spinal anesthesia (SA), for careful follow-up before, during, and after operations.Results. We show that it is also more stable in SA which is about 56 % in comparison to GA which is about 40 % but increased blood pressure is more in GA which was 32 % and 24 % in SA, but decreased blood pressure is also more in GA which was 28 % and in SA was 20 %. In this study, as shown, there is more stability in heart rate, which is 56 % in SA but in GA it is 32 % and the increase in heart rate was 34 % in SA but was 60 % in GA. The decreased heart rate was 10 % in SA and about 8 % in GA and the effect of SA is more stable.Conclusions. We found spinal anesthesia was more than general anesthesia in stability of blood pressure and heart rate and minimum or normal.

Effects of moderate sedation induced by propofol or midazolam on intracranial pressure

Introduction: Propofol and midazolam are the main options for moderate sedation in clinical practice. In addition, these drugs are used to reduce intracranial pressure in cases of intracranial hypertension, and their use in these situations is guided by limited evidence. Objective: To compare the effects of propofol and midazolam on intracranial pressure wave morphology in moderate sedation in patients undergoing upper digestive endoscopy. Methods: Sixty patients were included in this study, being divided into two groups, propofol and midazolam group. Intracranial pressure was monitored during and after upper digestive endoscopy, using non-invasive monitoring equipment developed by the company Brain4care. Arterial pressure was measured before and after the exam. Results: The propofol group had lower intracranial pressure (p=0.037) during moderate sedation compared to intracranial pressure after endoscopy and a significant decrease in systolic (p=0.0001) and diastolic pressure (p=0.001) after sedation. Midazolam, on the other hand, reduced systolic pressure (p=0.001), but didn’t change the other parameters after the procedure. There wasn’t a significant difference between the propofol and midazolam groups. Conclusion: There was no significant difference between the groups studied, however, analyses within the propofol and midazolam groups indicate that propofol, but not midazolam, causes changes in intracranial pressure in moderate sedation.

Examining temporal changes in model-optimized parameters using longitudinal hemodynamic measurements

BackgroundWe previously applied hemodynamic data to personalize a mathematical model of the circulation expressed as physically interpretable parameters. The aim of this study was to identify patterns in the data that could potentially explain the estimated parameter changes. This included investigating whether the parameters could be used to track the effect of physical activity on high blood pressure. Clinical trials have repeatedly detected beneficial changes in blood pressure after physical activity and uncovered changes in lower level phenotypes (such as stiffened or high-resistance blood vessels). These phenotypes can be characterized by parameters describing the mechanical properties of the circulatory system. These parameters can be incorporated in and contextualized by physics-based cardiovascular models of the circulation, which in combination can become tools for monitoring cardiovascular disease progression and management in the future.MethodsClosed-loop and open-loop models of the left ventricle and systemic circulation were previously optimized to data from a pilot study with a 12-week exercise intervention period. Basal characteristics and hemodynamic data such as blood pressure in the carotid, brachial and finger arteries, as well as left-ventricular outflow tract flow traces were collected in the trial. Model parameters estimated for measurements made on separate days during the trial were used to compute parameter changes for total peripheral resistance, systemic arterial compliance, and maximal left-ventricular elastance. We compared the changes in these cardiovascular model-based estimates to changes from more conventional estimates made without the use of physics-based models by correlation analysis. Additionally, ordinary linear regression and linear mixed-effects models were applied to determine the most informative measurements for the selected parameters. We applied maximal aerobic capacity (measured as VO2max\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext{VO2max}$$\\end{document}) data to examine if exercise had any impact on parameters through regression analysis and case studies.Results and conclusionsParameter changes in arterial parameters estimated using the cardiovascular models correlated moderately well with conventional estimates. Estimates based on carotid pressure waveforms gave higher correlations (0.59 and above when p<0.05\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$<0.05$$\\end{document}) than those for finger arterial pressure. Parameter changes over the 12-week study duration were of similar magnitude when compared to short-term changes after a bout of intensive exercise in the same parameters. The short-term changes were computed from measurements made immediately before and 24 h after a cardiopulmonary exercise test used to measure VO2max\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext{VO2max}$$\\end{document}. Regression analysis indicated that changes in VO2max\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext{VO2max}$$\\end{document} did not account for any substantial amount of variability in total peripheral resistance, systemic arterial compliance, or maximal left-ventricular elastance. On the contrary, changes in stroke volume contributed to far more explained variability. The results suggest that more research is required to be able to accurately track exercise-induced changes in the vasculature for people with pre-hypertension and hypertension using lumped-parameter models.

Examining temporal changes in model-optimized parameters using longitudinal hemodynamic measurements

BackgroundWe previously applied hemodynamic data to personalize a mathematical model of the circulation expressed as physically interpretable parameters. The aim of this study was to identify patterns in the data that could potentially explain the estimated parameter changes. This included investigating whether the parameters could be used to track the effect of physical activity on high blood pressure. Clinical trials have repeatedly detected beneficial changes in blood pressure after physical activity and uncovered changes in lower level phenotypes (such as stiffened or high-resistance blood vessels). These phenotypes can be characterized by parameters describing the mechanical properties of the circulatory system. These parameters can be incorporated in and contextualized by physics-based cardiovascular models of the circulation, which in combination can become tools for monitoring cardiovascular disease progression and management in the future.MethodsClosed-loop and open-loop models of the left ventricle and systemic circulation were previously optimized to data from a pilot study with a 12-week exercise intervention period. Basal characteristics and hemodynamic data such as blood pressure in the carotid, brachial and finger arteries, as well as left-ventricular outflow tract flow traces were collected in the trial. Model parameters estimated for measurements made on separate days during the trial were used to compute parameter changes for total peripheral resistance, systemic arterial compliance, and maximal left-ventricular elastance. We compared the changes in these cardiovascular model-based estimates to changes from more conventional estimates made without the use of physics-based models by correlation analysis. Additionally, ordinary linear regression and linear mixed-effects models were applied to determine the most informative measurements for the selected parameters. We applied maximal aerobic capacity (measured as VO2max\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext{VO2max}$$\\end{document}) data to examine if exercise had any impact on parameters through regression analysis and case studies.Results and conclusionsParameter changes in arterial parameters estimated using the cardiovascular models correlated moderately well with conventional estimates. Estimates based on carotid pressure waveforms gave higher correlations (0.59 and above when p<0.05\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$<0.05$$\\end{document}) than those for finger arterial pressure. Parameter changes over the 12-week study duration were of similar magnitude when compared to short-term changes after a bout of intensive exercise in the same parameters. The short-term changes were computed from measurements made immediately before and 24 h after a cardiopulmonary exercise test used to measure VO2max\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext{VO2max}$$\\end{document}. Regression analysis indicated that changes in VO2max\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext{VO2max}$$\\end{document} did not account for any substantial amount of variability in total peripheral resistance, systemic arterial compliance, or maximal left-ventricular elastance. On the contrary, changes in stroke volume contributed to far more explained variability. The results suggest that more research is required to be able to accurately track exercise-induced changes in the vasculature for people with pre-hypertension and hypertension using lumped-parameter models.

A Single Large Center Experience of Medically Treating Impending Compartment Syndrome of Tibia with Deflazacort

Abstract Background: Acute compartment syndrome (ACS) is a rare condition characterized by increased pressure in the closed compartments of the limbs resulting in ischemic tissue necrosis. Most of the patients present following limb fractures. Apart from surgical options such as fasciotomy, which has inherent complication of myonecrosis and severe infection, conservative management with corticosteroids hasshown to be useful. We conducted this study to understand the changes in intra-compartment pressures in ACS after regular monitoring following corticosteroids treatment. Materials and Methods: Consecutive patients of ACS following closed fractures lower limb fractures of tibia or fibula from June 2021 to February 2022 were included. The intra-compartment pressure was measured using a manometer at the time of presentation and after 3, 6, 12, 24, 48, 72, and 96 h of treatment with tab Deflazacort 6 mg × 1 Tablet × Tds. The efficacy of treatment was assessed on the basis of changes in intra-compartmental pressure and improvement in the clinical signs and symptoms of ACS. Results: The study included 60 patients, most (63.3%) suffering from fracture of proximal tibia or fibula (36.7%), presenting with ACS. The mean age was 32.4 ± 8.6 years and most (53%) were males. We observed a statistically significant change (P &lt; 0.05) in the intra-compartment pressures from the baseline to 3 h, 24 h, 48 h, 72 h, and 96 h after corticosteroid treatment. None of these patients suffered from ischemic necrosis or any other complication of ACS. Conclusion: Our results suggest that the timely diagnosis of ACS in patients with lower limb fractures and early initiation of conservative management with corticosteroids can be a mainstay of treatment in these patients. This conservative approach can avoid surgical intervention and reduce the cost of management.

Enhanced Pressure Response of Edge-Deposited Graphene Nanomechanical Resonators.

Nanomechanical resonators made of suspended graphene exhibit high sensitivity to pressure changes. Nevertheless, the graphene resonator pressure performance is affected owing to the gas permeation problem between the graphene film and the substrate. Therefore, we prepared edge-deposited graphene resonators by focused ion beam (FIB) deposition of SiO2, and their gas leakage velocities and pressure-sensing ability were demonstrated. In this paper, we characterize the pressure-sensing response and gas leakage velocities of graphene membranes using an all-optical actuation system. The gas leakage velocities of graphene resonators with diameters of 10, 20, and 40 μm are reduced by 5.0 × 106, 2.0 × 107, and 8.1 × 107 atoms/s, respectively, which demonstrates that the edge deposition structure can reduce the gas leakage of the resonator. Furthermore, the pressure-sensing performance of three graphene resonators with different diameters was evaluated, and their average pressure sensitivities were calculated to be 3.4, 2.4, and 1.9 kHz/kPa, with the largest full-range hysteresis errors of 0.6, 0.7, and 1.0%, respectively. The temperature stabilities of the three sizes of resonators in the temperature range of 300-400 K are 0.016, 0.015, and 0.016%/K, and the maximum resonance frequency drift over 1 h is 0.0058, 0.0048, and 0.0112%, respectively. This work has great significance for the improvement of gas leakage velocity characterization of graphene membrane and graphene resonant pressure sensor performance optimization.

Impact of oxygen vacancy on luminescence properties of dysprosium-doped zinc oxide thin films

Pristine and dysprosium-doped ZnO thin films, highly c-axis oriented, were grown on a c-Al2O3 substrate using the pulsed laser deposition technique. During the deposition process, the growth was impacted by changes in the oxygen partial pressure. The structural, optical, and compositional properties of the pristine and dysprosium-doped ZnO thin films were systematically characterized using various state-of-the-art experimental techniques. The crystallinity associated with these films was observed to be highly dependent on the oxygen partial pressure maintained during the growth process. An average optical transparency of more than ∼90% in the visible spectral range (i.e., 400–800 nm) was observed for all specimens. For doped specimens, expected intra-4fn emissions of (dysprosium) Dy3+ ions that emanated from the 4F9/2 energy state were observed in room-temperature photoluminescence spectra under direct excitation. The Jacobian-transformed wavelength-to-energy plot for Dy-doped ZnO thin films in the UV-Visible region revealed intriguing findings. Specifically, it depicted a prominent peak at 2.82 eV, indicative of the energy state of Dy3+ ions, alongside intense band-edge emission and various defect-related emissions. The intensity of these transitions was observed to depend on the oxygen partial pressure kept during deposition. An x-ray photoelectron spectroscopy analysis of the doped specimen confirmed the +3 oxidation state of dysprosium into the ZnO matrix. These results provide a promising approach for controlling the doping and growth strategy of Dy-doped ZnO thin films, thereby opening up a wide range of applications and enhancement for next-generation optoelectronic devices.

Ocular vestibular-evoked myogenic potential assists in differentiation of multiple system atrophy from Parkinson's disease.

Vestibular-evoked myogenic potentials (VEMPs) can help assess otolithic neural pathway in the brainstem that may also participate in cardiovascular autonomic function. Parkinson's disease (PD) is associated with altered VEMP responses; however, the association between VEMP abnormalities and multiple system atrophy (MSA) remains unknown. Therefore, we compared the extent of otolith dysfunction using ocular (oVEMP) and cervical VEMP (cVEMP) between MSA and PD. We analyzed the clinical features and VEMP and head-up tilt table test (HUT) findings using the Finometer in 24 patients with MSA and 52 with de-novo PD, who had undergone neurotologic evaluation in a referral-based university hospital in South Korea from January 2021 to March 2023. MSA was associated with bilateral oVEMP abnormality (odds ratio [95% confidence interval] = 9.19 [1.77-47.76], p=0.008). n1-p1 amplitude was negatively correlated with Unified Multiple System Atrophy Rating Scale I-II scores in patients with MSA (r=-0.571, p=0.033), whereas it did not correlate with Movement Disorder Society-Unified Parkinson's Disease Rating Scale-III scores in patients with PD (r=-0.051, p=0.687). n1 latency was negatively correlated with maximum changes in systolic blood pressure within 15 s during HUT in patients with PD (r=-0.335, p=0.040) but not in those with MSA (r=0.277, p=0.299). In conclusion, bilaterally abnormal oVEMP responses may indicate the extent of brainstem dysfunction in MSA. oVEMP reflects the integrity of otolith-autonomic interplay, reliably assists in differentiating between MSA and PD, and helps infer clinical decline.

Sodium bicarbonate treatment and clinical outcomes in chronic kidney disease with metabolic acidosis: a meta-analysis.

In patients with chronic kidney disease (CKD), impaired kidney acid excretion leads to the onset of metabolic acidosis (MA). However, the evidence is not yet conclusive regarding the effects of sodium bicarbonate in treating CKD with MA. Databases with PubMed, Embase, and the Cochrane Library were used to search for randomized controlled trials from the inception until November 11, 2023 to identify randomized controlled trials investigating the effect of sodium bicarbonate in participants with CKD and MA. The primary outcome was the change in estimated glomerular filtration rate (eGFR). Secondary outcomes included hospitalization rates, change in systolic blood pressure (SBP), all-cause mortality, and mid-arm muscle circumference (MAMC). A random-effects model was applied for analysis, and subgroup, sensitivity analyses were also performed. Fourteen RCTs comprising 2,037 patients demonstrated that sodium bicarbonate supplementation significantly improved eGFR (standardized mean difference [SMD]: 0.33, 95% CI: 0.03 to 0.63, P = 0.03). The group receiving sodium bicarbonate had a lower hospitalization rate (odds ratio: 0.37, 95% CI: 0.25 to 0.55, P < 0.001). Higher MAMC was observed with sodium bicarbonate treatment compared with those without (SMD:0.23, 95% CI: 0.08 to 0.38, P = 0.003, I2 < 0.001). However, higher risk of elevated SBP was found with sodium bicarbonate treatment (SMD:0.10, 95% CI: 0.01 to 0.20, P = 0.03). No significant difference in all-cause mortality was noted. In patients with CKD and MA, sodium bicarbonate supplementation may provide potential benefits in preventing the deterioration of kidney function and increasing muscle mass. However, treatment may be associated with higher blood pressure. Due to the risk of bias stemming from the absence of double-blinded designs and inconsistencies in control group definitions across the studies, further research is crucial to verify these findings.