Gas Analysis Research Articles

#1772 Comparison of interpretation of acid-base disorder in patients with critical illness: nephrologist versus ChatGPT

Abstract Background and Aims The generative pre-trained transformer (GPT), a type of large language model (LLM), is now playing a huge role in driving innovation in fields of medical education, diagnosis and treatment and with a process of continuous improvement it will itself be able to become beacons of sustainability. Medical professionals expect that they may have help from LLMs to diagnose patients more accurately and efficiently, but it is unclear whether current LLMs are well-trained and validated on real-world clinical data. In this study, we compared the performance of ChatGPT, a representative LLM, MDCalc, an online medical calculator, and human nephrologist for their diagnostic accuracies of acid-base gas analysis in critically ill cases. Method This study included 130 patients admitted to intensive care unit with varying medical conditions. All variables were obtained during the first 24 hours after admission. Results The Fleiss’ Kappa between the interpretations of nephrologist, ChatGPT and MDCalc with the acid-base gas analysis for acid-base disorders showed that Fleiss’ Kappa value was −0.138 (95% CI −0.216 to −0.059), indicating no agreement among the judgments of human doctor, LLM and online medical calculator in critically ill patients for the interpretation of acid-base status. MDCalc showed that all patients had mixed acid-base disorders while nephrologist that 4 patients had simple acid-base disorder and 1 patient had normal acid-base balance. By contrast, ChatGPT reported that 51 patients had only simple acid-base disorder. Furthermore, according to ChatGPT, normal acid-base balance was found in 27 patients, who were all diagnosed as having acid-base disorders by MDCalc or nephrologist. Conclusion We found that current ChatGPT does not yet provide better diagnostic performance for interpreting acid-base balance in critically ill patients who with usually have mixed acid-base disorders compared with an existing online medical calculator or nephrologist.

#1001 Model-based profiling of bicarbonate supplementation during a hemodialysis cycle

Abstract Background and Aims Bicarbonate is delivered to hemodialysis (HD) patients via diffusion following a concentration gradient across the dialyzer membrane. However, the concentration of bicarbonate in the dialysis fluid ([HCO3]d) is usually not individualized for the specific patient's conditions, as no clear guidelines are provided, which leads to suboptimal pre- and post-dialytic plasma bicarbonate concentrations ([HCO3]p) during each treatment cycle. We used a mathematical model to predict the outcomes of a week-long HD cycle with time-dependent [HCO3]d in 24 patients, tuning the [HCO3]d prescription to keep the simulated pre-dialytic [HCO3]p in the range 22-24 mEq/L throughout the week. The [HCO3]d profiles thus developed were then tested, and [HCO3]p during HD compared with those using a constant [HCO3]d in the same patients. Method The compartmental model (Pietribiasi et al PLOS ONE 2023) describes the transport of total CO2, O2, and total buffer base in arterial and mixed-venous blood (plasma and red blood cells), tissues (interstitial and intracellular fluid), and lung capillaries and alveoli, calculating derivate quantities such as bicarbonate concentration, pH, partial pressure of CO2. The patients underwent one week of standard HD with constant [HCO3}d (Week 1, [HCO3]d = 33.6 ± 1.8 mEq/L) consisting of 3 sessions (HD1, HD2, HD3) to estimate the baseline model parameters and, successively, an intervention week (Week 2), during which the model-derived [HCO3]d profiles were implemented. Each profile consisted of a single step increase after 2 hours of HD, the two values of [HCO3]d chosen for each session and patient according to the model's simulations. Blood samples for the blood gas analyzer were taken before and after each session, and each hour during HD2. Results [HCO3]p profiles in Week 2 showed a more linear increase compared those of Week 1 (Fig. 1). The efficacy of the response to the model-based treatment was different depending on whether the intervention aimed to decrease or increase pre-dialytic [HCO3]p during Week 2 (Fig. 2). In the group of patients attempting to decrease pre-dialytic [HCO3]p (Decrease group, n = 10, average [HCO3]d = 31.3 ± 1.5 mEq/L), a significant fraction of sessions achieved the target (60% across the whole week). In contrast, among the patients attempting to increase pre-dialytic [HCO3]p (Increase group, n = 6, average [HCO3]d = 35.3 ± 2.0 mEq/L), the model-based prescription was effective only in increasing post-dialytic concentration (20% of sessions achieved pre-dialytic targets). By comparison, during Week 1 only 30% and 10% of sessions were in the target range for Decrease and Increase groups, respectively. Patients for which we didn't want to alter pre-dialytic [HCO3]p were termed the Neutral group (n = 8, average [HCO3]d = 33.3 ± 2.1 mEq/L, 40% and 50% of sessions in the target [HCO3]p range in Week 1 and 2, respectively). Conclusion The model-based profiling intervention was only partially successful in achieving the targets for pre-dialytic [HCO3]p in Week 2. The reasons why pre-dialytic [HCO3]p were resistant to the model-based [HCO3]d in the Increase group are not clear, but it could be that the increase in the average [HCO3]d was too small (6-7% higher than Week 1). However, in the Decrease group a similar difference was sufficient to produce a more marked decrease in pre-dialytic [HCO3]p. The profiling of [HCO3]d was shown to be effective in reducing the time the patients spend at higher [HCO3]p. Nevertheless, our study demonstrated that, upon refinement, mathematical modeling can be used to develop individualized treatments to pilot the markers of the acid-base response to HD towards desired values.

#879 Impacts on ionized magnesium and total magnesium by the conversion to higher dialysate magnesium concentration

Abstract Background and Aims Hypermagnesemia is detrimental to hemodialysis patients whose renal function is compromised. However, recent observational study suggested the lower mortality rate was observed in the patients with mild hypermagnesemia. Even though the serum magnesium concentration (tMg) of the patients were frequently higher than the reference range of the tMg, one study reported 90% of the cases were within the reference range of the ionized magnesium (iMg) which is a physiologically active fraction of magnesium (Mg) in the blood. This is due to the higher serum phosphorous level in the hemodialysis patients, and negative correlation between iMg and the serum phosphorous, and anion gap. Current guideline recommends Mg level should be managed to be 3.0 mg/dL at pre-dialysis blood test. However, not much are known what iMg level is optimal. This study aimed to assess the impacts on iMg and tMg level of the patients by the conversion of the routinely-used dialysate containing 1.0 mEq/L (0.5 mmol/L) Mg to higher dialysate Mg concentration. Method This longitudinal study was conducted at Shingashi Renal Centre, Fujimino Renal Centre, and Kawagoe-minami Renal Centre. Out of 289 stable maintenance hemodialysis patients agreed to participate in the study, 42 were excluded due to death, changing hospital, or hospitalization. A total of 247 patients who are on regular hemodialysis treatment at least 6 months with commercially available dialysate mixture TA1 (Mg concentration: 1.0 mEq/L (0.5 mmol/L)) were included for the analysis. Dialysate Mg concentration was then increased to 1.25 mEq/L (0.625 mmol/L) by using a commercially available dialysate mixture TA5. Blood tests were carried out on the day of the first hemodialysis session of the week (Monday or Tuesday) before dialysate Mg concentration conversion and at 1, 4, 12, and 24 weeks. The iMg concentrations were analyzed using the ion-selective electrode on blood gas analyzer StatProfile Prime Plus (Nova Biomedical, Waltham, MA, USA). The tMg concentrations were determined by using Xylidylblue. Results Mean age of the 247 enrolled patients was 70.3ion-selective electrode on blood gas analyzer StatProfile Prime Plus (Nova Bidecreased significantly (TA1-pre:2.58±0.36mg/dL→TA1-post:2.18±0.16mg/dL, TA5-pre (24wk): 2.74±0.35mg/dL→TA5-post: 2.44±0.15mg/dL). After conversion to higher Mg dialysate TA5, post-dialysis tMg increased in comparison with TA1. After conversion to the higher Mg dialysate, iMg increased as well significantly (TA1-pre:0.64±0.11mmol/L→TA1-post:0.49±0.05mmol/L, TA5-pre:0.70±0.11mmol/L→0.60±0.04mmol/L) . However, iMg of TA1-post was close to the lower limit of the reference range of iMg (Fig. 1). Conclusion Hemodialysis patients’ iMg level became manageable within reference range by the conversion of the dialysate from TA1 to TA5 and the clinical advantage of iMg monitoring with hemodialysis patients were demonstrated. A slight increase in dialysate Mg concentration from 1.0 mEq/L to 1.25 mEq/L increased the iMg/tMg ratio, and iMg was within the normal range even when the pre-dialysis reference value of 3 mg/dL was not reached.

#2418 Effects of correction of acidosis on body composition and biochemical parameters in CKD patients on maintenance hemodialysis

Abstract Background and Aims Metabolic acidosis is a common problem in patients of chronic kidney disease and patients on maintenance hemodialysis. In resource poor countries, due to financial constraints frequency of dialysis and compliance to medication is adversely affected. This leads to worsening of clinical condition of patient and requirement of in hospital care, many times intensive care, further increasing cost of treatment. Metabolic acidosis has implications on bone and muscle health. Aim of our study was to assess the changes in body composition (fat percentage and lean body mass), changes in third space fluid, biochemical parameters, number of admissions and requirement of blood transfusions before and after correction of metabolic acidosis. Method This was a prospective, observational study. 25 patients on maintenance hemodialysis at our center were included in the study. Bio-impedance analysis (BIA), biochemical parameters (Complete blood counts, renal function tests, serum calcium and phosphorous, liver function tests, Blood gas analysis) were done at baseline before starting bicarbonate supplementation. Number of admissions and blood transfusions in 3 months prior to initiation of bicarbonate supplementation were noted. The oral bicarbonate supplementation was increased from baseline, based on the baseline blood gas analysis. The same parameters were assessed after 3 months and analyzed. Results At the end of 3 months we observed that there was significant reduction (p < 0.05) in total leucocyte counts (mean 8100/cumm to 6800/cumm), urea (mean 113.7 mg/dL to 83.72 ng/dL), creatinine (mean 7.87 mg/dL to 6.68 mg/dL), phosphorous (mean 5.18 mg/dL to 4.43 mg/dL), SGOT (mean 56.52 IU to 25.2 IU) and SGPT (mean 46.48 IU to 22.88 IU) with a trend of decrease (p ≤ 0.1) in percentage of extra cellular water (27.31% to 25.03%), lean body mass (44.27 kg to 43.0 kg) and trend of increase (p ≤ 0.1) in body fat composition (15.62 kg to 18.82 kg) and body fat percentage (26.924% to 31.90). There was a reduction in third space fluid (0.88 lit to 0.43 lit). The number of hospitalizations reduced (15 three months prior to initiation of therapy to 7 after initiation of therapy) and number of blood transfusions required also reduced (21 before initiation to 10 after initiation of therapy). Conclusion We concluded that correction of acidosis probably reduces the inflammation in patients of CKD on maintenance hemodialysis. This could be seen from the reduced total leucocyte counts, liver enzymes, urea and creatinine values. Changes in body composition with increased total fat mass, fat percentage and decreased lean mass was also noted. There was also a significant reduction in hospitalizations and number of blood transfusions.

Multi-parameter-based fuzzy logic diagnostic system for health assessment of power transformer

ABSTRACT Power transformers are the most valuable assets in the power system. An appropriate asset management is therefore essential for ensuring a reliable power supply to the utility managers. This is accomplished through continuous transformer condition monitoring. The transformers’ asset management involves a severe investigation into its insulation health index. It is determined by utilising several diagnostic parameters of transformer insulation. In this context, a novel fuzzy logic-based health index model has been proposed in the present paper to find the overall health condition of transformers. This model utilises the results extracted from several important diagnostic tests of transformer insulation, such as furan analysis and dissolved gas analysis. The validity of the proposed fuzzy logic model has been tested using real data from 200 transformer samples. These samples are collected from different-rated transformers of the Himachal Pradesh State Electricity Board (HPSEB), India. Further, the efficacy of the proposed fuzzy logic model has been validated against the expert model presented in literature. It is revealed from the comparison that the accuracy of the present proposed model is 92%. Also, it is observed that the proposed fuzzy logic model is very effective in interpreting dissolved gases and the other diagnostic test results of the transformer.

EXPLORATORY ANALYSIS OF URINE PO2 PERI-PROCEDURAL KINETICS AND CI-AKI PROGNOSTIC ABILITIES IN PATIENTS UNDERGOING PCI.

Novel contrast-induced acute kidney injury (CI-AKI) biomarkers are needed to detect earlier and with greater precision the pathophysiological changes in renal medulla associated with kidney damage. We prospectively assessed the kinetics of urine oxygen tension (PO2) in control healthy individuals, and its prognostic ability for CI-AKI in patients undergoing percutaneous coronary intervention (PCI). We enrolled 202 consecutive patients (78% men, mean age 66±10 years) treated with elective or urgent PCI. PO2 was measured using a point-of-care (POC) standard blood gas analyzer at 3 time points (baseline, post -within 3 hours- PCI and at 24 hours post PCI) in urine samples. CI-AKI was defined as an increase of ≥25% or ≥0.5 mg/dl in pre-PCI serum creatinine at 48 hours post PCI. Between baseline and post-PCI measurements, patients without CI-AKI showed a decrease of -37 (36) mmHg in PO2 urine levels whereas patients with CI-AKI showed a decrease of only -23 (38) mmHg. (P=0.014). Using ROC analysis, percentage change in urine PO2 immediately after PCI relative to baseline levels, significantly predicted CI-AKI (AUC 0.804 95%CI 0.717-0.892). A significant drop in urine oxygen tension appears as a normal response of the kidney medulla to an acute insult (contrast media) immediately post PCI with a recovery to baseline levels 24 hours later. Absence or attenuation of this drop in urine oxygen tension could predict CI-AKI earlier and more precisely.

#2996 Diffuse alveolar haemorrhage in antiphospholipid syndrome—a rare case

Abstract Background and Aims Diffuse alveolar haemorrhage (DAH) is a serious manifestation of diseases such as systemic lupus erythematosus (SLE) and, apparently in a paradoxical manner, antiphospholipid syndrome (APS). Inflammation resulting from the deposition of immune complexes in alveolar capillaries appears to contribute to the pathophysiology of DAH, SLE and APS. Symptoms include cough, dyspnoea, haemoptysis or fever. It is associated with a drop in haemoglobin, respiratory failure and diffuse infiltrates on imaging exams. Bronchoscopy is diagnostic. It is important to exclude infection as treatment includes high-dose corticosteroid therapy and other immunosuppressive drugs. We present a challenging case regarding the diagnostic and therapeutic approach to this pathology. Case report This is the case of a 52-year-old Caucasian female, with a history of SLE, APS, splenectomy due to thrombocytopenia, IgM Kappa monoclonal gammopathy and indolent non-Hodgkin lymphoma. She was medicated with prednisolone 5 mg and warfarin (target INR between 2 and 3). The patient was observed due to a 1-day history of fever, nasal obstruction and odynophagia, associated with progressively worsening fatigue. On examination, she was pale, eupnoeic, tachycardic, with bibasal rales and a hyperaemic oropharynx. Lab workup results were the following: haemoglobin 7 g/dL (11.7 g/dL 3 months before), VGM 71 fL, presence of schistocytes, leukocytes 13.7 G/L, neutrophils 11.1 G/L, PCR 4.6 mg/dL, platelets 170 G/L, INR 3.6, aPTT 45 sec, negative D-Dimers, urea 54 mg/dL, creatinine 1.4 mg/dL, LDH 431 IU/L, normal haptoglobin, negative Coombs test. In arterial blood gas analysis, pO2 was 61 mmHg and lactate was 5 mmol/L. Chest X-ray showed bilateral basal cotton-wool infiltrates and chest CT showed bilateral ground-glass pattern. The rest of the investigation included no complement consumption, negative anti-ds-DNA antibody, positive lupus anticoagulant, anticardiolipin and anti-beta2-glycoprotein antibodies, negative cryoglobulins and no evidence of progression of the lymphoproliferative disease. She was admitted to the intensive care unit due to suspicion of atypical/viral pneumonia vs. DAH. Oxygen therapy, empirical antibiotic therapy with ceftriaxone and clarithromycin and oral methylprednisolone 1 mg/Kg/day were started. She needed blood transfusion, although without visible blood loss. Bronchofibroscopy was performed, with bronchoalveolar lavage suggestive of DAH, so it was decided to start intravenous pulses of methylprednisolone, plasmapheresis, and intravenous immunoglobulin (IVIG). Warfarin was changed to unfractionated heparin. The patient had clinical, analytical and radiological improvement. Due to the lack of evidence of infection, antibiotics were stopped after 7 days. The patient was discharged under weaning corticosteroid therapy and monthly IVIG (during 5 months), without recurrence in the following year. Conclusion This is a rare case of oligosymptomatic DAH in a patient with SLE and APS. The literature currently available on DAH in the context of SLE or APS is scarce and its treatment is mainly dependent on the experience of each medical centre. Corticosteroid therapy is consensual, with greater variability in other corticosteroid-sparing therapies. In the case of patients with APS, anticoagulation is a challenge, and it is important to resume it as soon as the bleeding is controlled due to the risk of thrombotic events.

ANALYSIS OF THE PROSPECTS OF APPLICATION OF NATURAL GAS LEAK DETECTION METHODS TO INCREASE THE EFFICIENCY OF ATMOSPHERIC AIR MONITORING AT HTS FACILITIES

The activities of the oil and gas industry enterprises, in particular the objects of gas transportation systems (GTS), are accompanied by a significant anthropogenic impact on the environment. The atmospheric air itself is significantly affected, since many technological processes are accompanied by emissions of natural gas (organized, unorganized and emergency) and, as a result, a significant amount of volatile substances, many of which are dangerous and harmful, enter the atmosphere. There is a wide range of methods for detecting gas leaks from elements of gas transportation systems. Ways of classifying methods directly depend on the features that form the basis of their distribution. However, the insufficient definition of the classification features, their "one-sidedness" do not allow a full assessment of the shortcomings and advantages of certain methods and means, and, therefore, the possibility of their application to increase the effectiveness of atmospheric air monitoring at HTS facilities in order to ensure environmental safety. The main tasks solved in this article are the formulation of the optimal classification of existing methods of controlling the presence of gas leaks in terms of applicability in environmental monitoring systems of atmospheric air; analysis of their advantages and disadvantages; substantiation of the expediency and perspective of using these means and methods to ensure constant monitoring of the state of atmospheric air at GTS facilities. A classification of methods and means of control is proposed based on the level of application of technical means, according to which all methods are divided into organoleptic, hardware and computational (software-mathematical). According to the results of the analysis of the data of the groups, it was determined that, from the point of view of the prospects of application in the atmospheric air quality monitoring systems at the GTS facilities, hardware means, namely gas analyzers, have the most advantages.

Germany's Way from Russian Natural Gas to Green Hydrogen: Network Data, Procedures, and Topologies for Feasible Transition Paths to a Green Hydrogen Transport Infrastructure in Germany, GreenHyDE [gri:n'haɪ̯də] –

Hydrogen—and thus hydrogen transport—will play an important role in the German and European transition to climate neutrality. A German hydrogen transport network is currently being planned, but its appropriate structure and size highly depend on the spatial distribution of hydrogen demand and supply and their development over time. Moreover, the security of supply with both, hydrogen and natural gas, needs to be guaranteed during the transition period, as repurposing of the existing natural gas transmission system is a highly advantageous option for the building of hydrogen networks. Therefore, the integrated analysis of natural gas and hydrogen networks is a necessary and urgent, though complex, field of research. For this purpose, the article presents the database for the existing German natural gas transmission system (which in parts will be repurposed for hydrogen transport) and procedures for the development and evaluation of network topologies for both gases. The results for the German case show feasible development steps for the design of green hydrogen transport networks and the transition from natural gas in different scenarios. Open access to data and tools for technoeconomic assessment is provided.

Techno‐economic and life cycle analysis of renewable natural gas derived from anaerobic digestion of grassy biomass: A US Corn Belt watershed case study

AbstractRestoring native grassland vegetation can substantially improve ecosystem service outcomes from agricultural watersheds, but profitable pathways are needed to incentivize conversion from conventional crops. Given growing demand for renewable energy, using grassy biomass to produce biofuels provides a potential solution. We assessed the techno‐economic feasibility and life cycle outcomes of a “grass‐to‐gas” pathway that includes harvesting grassy (lignocellulosic) biomass for renewable natural gas (RNG) production through anaerobic digestion (AD), expanding on previous research that quantified ecosystem service and landowner financial outcomes of simulated grassland restoration in the Grand River Basin of Iowa and Missouri, United States. We found that the amount of RNG produced through AD of grassy biomass ranged 0.12–45.04 million gigajoules (GJ), and the net present value (NPV) of the RNG ranged −$97 to $422 million, depending on the combination of land use, productivity, and environmental credit scenarios. Positive NPVs are achieved with environmental credits for replacement of synthetic agricultural inputs with digestate and clean fuel production (e.g., USEPA D3 Renewable Identification Number, California Low Carbon Fuel Standard). Producing RNG from grassy biomass emits 15.1 g CO2‐eq/MJ, which compares favorably to the fossil natural gas value of 61.1 g CO2‐eq/MJ and exceeds the US Environmental Protection Agency's requirement for cellulosic biofuel. Overall, this study demonstrates opportunities and limitations to using grassy biomass from restored grasslands for sustainable RNG production.

Management of neonates with respiratory distress syndrome in resource-limited settings.

In South Africa, prematurity stands as one of the foremost causes of neonatal mortality. A significant proportion of these deaths occur because of respiratory distress syndrome of prematurity. The implementation of non-invasive respiratory support, such as continuous positive airway pressure (CPAP), has demonstrated both safety and efficacy in reducing mortality rates and decreasing the need for mechanical ventilation. Given the absence of blood gas analysers and limited radiological services in many district hospitals, the severity of respiratory distress is often assessed through observation of the infant's work of breathing and the utilisation of bedside scoring systems. Based on the work of breathing, non-invasive therapy can be commenced timeously. While evidence supporting the use of high-flow nasal cannula as a primary treatment for respiratory distress syndrome remains limited, it may be considered as an alternative, provided that CPAP machines are available. The purpose of this article is to advocate the use of non-invasive therapy in low resource-limited settings and describe the indications, contraindications, complications, and application of CPAP therapy. This would benefit healthcare workers, especially in low-care settings and district hospitals.

Impact of an air bubble within the syringe on test results obtained with a modern blood gas analyzer

Background. Minimizing air aspiration by carefully filling blood gas syringes is crucial to prevent air contamination from causing undesirable variations in gasses and other molecules. While some previous studies investigated this aspect, these are now outdated and only analyzed a limited number of blood gas parameters. Thus, we investigated the effects air contamination in the syringe using a modern blood gas analyzer. Methods. We sampled venous blood from 17 laboratory workers (mean age: 46±11 years; 10 women), filling two consecutive blood gas syringes. The first was filled exactly to its nominal volume (i.e., 1.0 mL), while the second was filled with 0.8 mL of blood and 0.2 mL of ambient air. Blood gas analysis was performed in each syringe using an identical analyzer. Results. In the syringe with the air bubble, we found statistically significant increase in pH (0.1%), pO2 (10.8%), SO2 (11.2%), total hemoglobin (3.0%), and hematocrit (2.7%), while values of pCO2 (-4.8%), sodium (-0.5%), and ionized calcium (-1.3%) were significantly reduced. With exception of pH, all these changes exceeded the performance specifications. Potassium, chloride, glucose, lactate, COHb and MetHb values remained unchanged. Conclusion. These findings confirm that air bubbles must be removed as soon as possible after sampling from blood gas syringes to prevent artifactual test results and misleading clinical judgment and inappropriate treatment. When blood gas syringes are received in the laboratory with air bubbles inside, the most vulnerable parameters (i.e., pO2, SO2, pCO2, sodium, ionized calcium, hematocrit and hemoglobin) should be suppressed.

Prognostic value of biohybrid screening results for assessing cancer risk using the example of lung cancer

Introduction. One of the leading places in the structure of socially significant diseases in the Russian Federation is occupied by malignant neoplasms, among which cancer of the trachea, bronchi and lung occupies the first place in terms of prevalence. Screening for lung cancer is not carried out at the federal level in Russia; recommended screening measures include questionnaires to identify risk factors for the development of the disease (including occupational) and the formation of dispensary observation groups. The study aims to assess the prognostic value of a new method of biohybrid screening of lung cancer by exhaled air. Materials and methods. Scientists conducted a study at the National Medical Research Center of Oncology of the Ministry of Health, Russian Federation, with the participation of 24 conditionally healthy volunteers and 5 patients diagnosed with lung cancer in the early stages of the disease. The design of the study is simultaneous (on-line) with blinding; experts estimated the risk of systematic errors at 10 points on the QUADAS scale. The authors examined exhaled air samples on a gas analyzer (biohybrid detector) of the BGS-APK 02SZZ model, in which the sensor were animals — gray domesticated rats (Rattus norvegicus) with microelectrode matrices implanted into the olfactory bulb, and which were in the internal (ventilated) space of the analyzer in a state of drug anesthesia. The conclusion about the presence or absence of a risk of lung cancer was formed by an artificial neural network of the analyzer, at the input of which bioelectric signals from each microelectrode were received, which were preprocessed using a system for recording the focal activity of the olfactory analyzer. The specialists confirmed the presence or absence of a risk of lung cancer by a reference method, according to computed tomography of the chest in accordance with the Lung Imaging Reporting and Data System (LungRADS™). Results. During the study, experts determined the effectiveness indicators of the method of biohybrid lung cancer screening by exhaled air: sensitivity (64%), specificity (87%), prognosticality of negative and positive conclusions about the presence/absence of disease risk (82% and 72%, respectively). Conclusion. The safety, efficiency and throughput of the investigated method, together with the reproducibility of the analyzer's conclusions, meet the criteria of practicability to ensure the first (population-based) stage of lung cancer screening.

Thermodynamic and economic analysis of hierarchical gas–gas nuclear power plants and CHPs with high-temperature reactors and helium as the circulating medium

This paper presents the results of thermodynamic and economic analyses of innovative, gas–gas nuclear power plants and CHP plants with high-temperature gas-cooled reactors (HTGRs). In these power plants, two Joule cycles are performed in a hierarchical system. One is performed in the high-temperature range, the other in the low-temperature range. The reactor coolant is helium. It is also the circulating medium in the whole gas–gas system. The results of the thermodynamic and economic analyses presented in this paper cover a wide range of thermal capacities of HTGRs, from 100 to 3000 MW.

Airway pressure release ventilation (APRV) versus pressure support ventilation (PSV)-A prospective intervention trial comparing haemodynamic parameters in intensive care patients.

Assisted mechanical ventilation may alter the pressure profile in the thorax compared to normal breathing, which can affect the blood flow to and from the heart. Studies suggest that in patients with severe lung disease, airway pressure release ventilation (APRV) may be haemodynamically beneficial compared to other ventilator settings. The primary aim of this study was to investigate if APRV affects cardiac index in intubated intensive care patients without severe lung disease when compared to pressure support ventilation (PSV). The secondary aim comprised potential changes in other haemodynamic and ventilatory parameters. Twenty patients were enrolled in the intensive care unit (ICU) at Sahlgrenska University Hospital. Eligible patients met the inclusion criteria; 18 years of age or above, intubated and mechanically ventilated, triggering and stable on PSV mode, with indwelling haemodynamic monitoring via a pulse-induced continuous cardiac output (PiCCO) catheter. The study protocol started with a 30-min interval on PSV mode, followed by a 30-min interval on APRV mode, and finally a 30-min interval back on PSV mode. At the end of each interval, PiCCO outputs, ventilator outputs, arterial and venous blood gas analyses, heart rate and central venous pressure were recorded and compared between modes. There was no significant difference in cardiac index (3.42 vs. 3.39 L/min/m2) between PSV and APRV, but a significant increase in central venous pressure (+1.0 mmHg, p = .027). Furthermore, we found a significant reduction in peak airway pressure (-3.16 cmH2O, p < .01) and an increase in mean airway pressure (+2.1 cmH2O, p < .01). No statistically significant change was found in oxygenation index (partial pressure of O2 [pO2]/fraction of inspired oxygen) nor in other secondary outcomes when comparing PSV and APRV. There was no significant association between global end-diastolic volume index and cardiac index (R2 = 0.0089) or central venous pressure (R2 = 0.278). All parameters returned to baseline after switching the ventilator mode back to PSV. We could not detect any changes in cardiac index in ICU patients without severe lung disease during APRV compared to PSV mode, despite lower peak airwaypressure and increasedmean airway pressure.

Evaluation of the Activity of a Municipal Waste Landfill Site in the Operational and Non-Operational Sectors Based on Landfill Gas Productivity

This research identifies the productivity of landfill gas actively captured at a municipal waste landfill site with a waste mass exceeding 1 million Mg from sectors in the operational and non-operational phases, considering meteorological conditions. Based on the analysis of landfill gas, including emissions and composition (CH4, CO2, O2, and other gases), the processes occurring demonstrate the impact of the decomposition of deposited waste on the activity of the deposit. With average monthly gas emissions exceeding 960,000 m3, the average content of CH4 (30–63%) and CO2 (18–42%) and the varied content of O2 (0.3–9.8%) in individual sectors of the landfill site were significant. The statistically significant relationship between CH4, CO2, and landfill gas emissions exhibited a noticeable decrease in methane content. Despite the abandonment of waste storage, a high correlation is present between the emission level and methane content (0.59) and carbon dioxide (0.50). In the operational part of the landfill, this relationship is also statistically significant but to a lesser extent; Spearman’s R-value was 0.42 for methane and 0.36 for carbon dioxide. The operational and post-operational phases of the municipal waste landfill demonstrated a noticeable impact from the amount of precipitation, relative humidity, and air temperature, on landfill gas productivity. The generally progressive decline in the activity of the waste deposit, which reflects a decreasing trend in the methane content of approximately 2% annually in the total composition of landfill gas, as well as the share below 50%, indicates the need only to utilise landfill without producing energy.

Dynamics of gas composition and thermal behavior post explosions: An experimental investigation across varied initial concentrations

Gas explosion accidents are a leading cause of casualties in underground coal mines. This study investigates the variation patterns of explosion temperature and pressure under different initial gas concentration conditions using a 20 L explosion characteristic test system and high-precision sensors. Accurate post-explosion gas analyses were conducted using a GC9560 gas chromatograph. Our research aligns with global research, finding that initial gas concentrations within the range of 5.8%–13.3% generate maximum explosion pressures between 0.3 and 0.9 MPa, posing a significant overpressure hazard to humans. Comprehensive fitting analyses of various post-explosion gases reveal that at an initial gas concentration of 10.6%, the produced H2 can reach its lower explosion limit, indicating a risk of secondary explosions. Furthermore, post-explosion CO levels can peak at 9.87%, potentially causing poisoning or death, while elevated CO2 levels and diminished O2 concentrations could lead to asphyxiation. A unique observation at a 9.5% concentration was a secondary temperature rise, with the relationship between temperature delay, heating time, and initial gas concentration presenting a U-shaped pattern that mirrors theoretical expectations. This study advances the field by addressing research gaps in post-explosion gas analysis and emphasizing the necessity of precise monitoring and control of gas concentrations, thereby offering novel insights and substantial theoretical and practical contributions to the prevention of gas explosion incidents in underground coal mines.

Changes in the indicators of hemodynamics and oxygen transport in patients with idiopathic pulmonary arterial hypertension depending on their survival

Background. Idiopathic pulmonary arterial hypertension (IPAH) is a severe disease that affects the vessels of the pulmonary circulation and leads to right ventricular failure and death of patients. Indicators of hemodynamics and oxygen transport play central role in the progression and development of the disease. Objective: to evaluate indicators of hemodynamics, oxygen transport. Materials and methods. The study included 124 patients with IPAH. They were divided into two groups: alive patients (group 1) and those who died (group 2). All of them underwent general clinical examinations, a 6-minute walk test, transthoracic and speckle tracking echocardiography, right heart catheterization, blood gas analysis and calculation of hemodynamic parameters. Results. We calculated and compared the right (RVSWI) (19.93 ± 7.84 vs. 16.47 ± 4.67 g·m·m–2, p = 0.009) and left ventricular stroke work index (LVSWI) (39.47 ± 10.53 vs. 35.92 ± 11.19 g·m·m–2, p = 0.036) and their ratio (RVSWI/LVSWI) (0.59 ± 0.16 vs. 0.46 ± ± 0.13, p = 0.008), right (RVPC) (97.00 ± 2.16 vs. 1.82 ± 1.04 g·m, p = 0.001) and left ventricular pump coefficient (LVPC) (5.36 ± 4.84 vs. 4.41 ± 2.15 g·m, p = 0.04) and their ratio (RVPC/LVPC) (0.54 ± 0.19 vs. 0.44 ± 0.11, p = 0.05) in both groups of patients. Also, we found differences in partial pressure of carbon dioxide (PaCO2) of venous blood (34.5 ± 5.1 vs. 40.2 ± 6.9 mm Hg, p = 0.02), partial pressure of oxygen (PaO2) of arterial blood (90.2 ± 15.1 vs. 78.9 ± 11.2 mm Hg; p = 0.01), arteriovenous oxygen difference (A-vO2) (4.5 ± 1.2 vs. 5.0 ± 0.8 ml/dL, p = 0.02) between both groups. Conclusions. RVSWI, LVSWI, RVSWI/LVSWI, RVPC, LVPC, RVPC/LVPC were significantly different between the groups. The use of the above hemodynamic parameters can help in a deeper understanding of the prognosis in IPAH patients. Performance of oxygen transport indicators (PaCO2, PaO2) and A-vO2 in IPAH patients provides a broader understanding of the status and prognosis of this disease.

Electrochemical synthesis of C2 and C3 hydrocarbons from CO2 on an Ag electrode in DEME-BF4 containing H2O and metal hydroxides

In the electrochemical synthesis of hydrocarbon gases from CO2, the improvement of the selectivity of the product by controlling the composition of the electrolyte is attractive as a process that does not require complex electrode structures; however, little is known about the conversion process of CO2 at the ionic liquid-based electrolyte/metal electrode interface. In this study, the electrochemical conversion of CO2 and H2O to C2 and C3 hydrocarbons on a pure Ag electrode in N, N‑diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate (DEME-BF4) containing H2O and metal hydroxides, such as Ca(OH)2, NaOH, and CsOH, was investigated. Quantitative gas analysis of the samples obtained by potentiostatic electrolysis for 30 min in the melt with DEME-BF4:H2O:Ca(OH)2 molar ratio of 2:1:1.8 × 10−4 at room temperature demonstrated that C2H4, C2H6, C3H6, and C3H8 were produced, and the current efficiency of C3H8 was determined to be 11.3 %. The reactant was HCO3− coordinated with DEME+, BF4−, and Ca2+ ions, as identified by Raman spectroscopy combined with density functional theory (DFT) calculations. Moreover, the surface-enhanced Raman spectroscopic data revealed that the intermediate on the Ag electrode during potentiostatic electrolysis was adsorbed 2CO− interacting with Ca2+ ions. DFT simulations also demonstrated that Ca2+ increased the energetic stability of the 2CO−. This study showed that tailoring the electrolyte can lead to molecular-level changes in the phase transformation of CO2 in bulk solution and at the electrode/ionic liquid electrolyte interface and proposed a process that enables the synthesis of unique hydrocarbons such as C3.

Direct Measurement of Dissolved Gas Using a Tapered Single-Mode Silica Fiber.

Dissolved gases in the aquatic environment are critical to understanding the population of aquatic organisms and the ocean. Currently, laser absorption techniques based on membrane separation technology have made great strides in dissolved gas detection. However, the prolonged water-gas separation time of permeable membranes remains a key obstacle to the efficiency of dissolved gas analysis. To mitigate these limitations, we demonstrated direct measurement of dissolved gas using the evanescent-wave absorption spectroscopy of a tapered silica micro-fiber. It enhanced the analysis efficiency of dissolved gases without water-gas separation or sample preparation. The feasibility of this sensor for direct measurement of dissolved gases was verified by taking the detection of dissolved ammonia as an example. With a sensing length of 5 mm and a consumption of ~50 µL, this sensor achieves a system response time of ~11 min and a minimum detection limit (MDL) of 0.015%. Possible strategies are discussed for further performance improvement in in-situ applications requiring fast and highly sensitive dissolved gas sensing.