Oxygen Tension Research Articles

Ras-dependent activation of BMAL2 regulates hypoxic metabolism in pancreatic cancer.

To identify drivers of malignancy in human pancreatic ductal adenocarcinoma (PDAC), we performed regulatory network analysis on a large collection of expression profiles from laser capture microdissected samples of PDAC and benign precursors. We discovered that BMAL2 plays a role in the initiation, progression, post resection survival, and KRAS activity in PDAC. Functional analysis of BMAL2 target genes led us to hypothesize that it plays a role in regulating the response to hypoxia, a critical but poorly understood feature of PDAC physiology. Knockout of BMAL2 in multiple human PDAC cell lines revealed effects on viability and invasion, particularly under hypoxic conditions. Loss of BMAL2 also affected glycolysis and other metabolic processes. We found that BMAL2 directly regulates hypoxia-responsive target genes. We also found that BMAL2 is necessary for the stabilization of HIF1A upon exposure to hypoxia, but destabilizes HIF2A under hypoxia. These data demonstrate that BMAL2 is a master transcriptional regulator of hypoxia responses in PDAC and may serve as a long-sought molecular switch that distinguishes HIF1A- and HIF2A-dependent modes of hypoxic metabolism.

Carbon Dioxide Targets in Extracorporeal Membrane Oxygenation for Acute Respiratory Distress Syndrome.

Target values for arterial carbon dioxide tension (PaCO2) in extracorporeal membrane oxygenation (ECMO) for acute respiratory distress syndrome (ARDS) are unknown. We hypothesized that lower PaCO2 values on ECMO would be associated with lighter sedation. We used data from two independent patient cohorts with ARDS spending 1,177 days (discovery cohort, 69 patients) and 516 days (validation cohort, 70 patients) on ECMO and evaluated the associations between daily PaCO2, pH, and bicarbonate (HCO3) with sedation. Median PaCO2 was 41 (interquartile range [IQR] = 37-46) mm Hg and 41 (IQR = 37-45) mm Hg in the discovery and the validation cohort, respectively. Lower PaCO2 and higher pH but not bicarbonate (HCO3) served as significant predictors for reaching a Richmond Agitation Sedation Scale (RASS) target range of -2 to +1 (lightly sedated to restless). After multivariable adjustment for mortality, tracheostomy, prone positioning, vasoactive inotropic score, Simplified Acute Physiology Score (SAPS) II or Sequential Organ Failure Assessment (SOFA) Score and day on ECMO, only PaCO2 remained significantly associated with the RASS target range (adjusted odds ratio 1.1 [95% confidence interval (CI) = 1.01-1.21], p = 0.032 and 1.29 [95% CI = 1.1-1.51], p = 0.001 per mm Hg decrease in PaCO2 for the discovery and the validation cohort, respectively). A PaCO2 ≤40 mm Hg, as determined by the concordance probability method, was associated with a significantly increased probability of a sedation level within the RASS target range in both patient cohorts (adjusted odds ratio = 2.92 [95% CI = 1.17-7.24], p = 0.021 and 6.82 [95% CI = 1.50-31.0], p = 0.013 for the discovery and the validation cohort, respectively).

The Effects of Head Elevation on Intracranial Pressure, Cerebral Perfusion Pressure, and Cerebral Oxygenation Among Patients with Acute Brain Injury: A Systematic Review and Meta-Analysis.

Head elevation is recommended as a tier zero measure to decrease high intracranial pressure (ICP) in neurocritical patients. However, its quantitative effects on cerebral perfusion pressure (CPP), jugular bulb oxygen saturation (SjvO2), brain tissue partial pressure of oxygen (PbtO2), and arteriovenous difference of oxygen (AVDO2) are uncertain. Our objective was to evaluate the effects of head elevation on ICP, CPP, SjvO2, PbtO2, and AVDO2 among patients with acute brain injury. We conducted a systematic review and meta-analysis on PubMed, Scopus, and Cochrane Library of studies comparing the effects of different degrees of head elevation on ICP, CPP, SjvO2, PbtO2, and AVDO2. A total of 25 articles were included in the systematic review. Of these, 16 provided quantitative data regarding outcomes of interest and underwent meta-analyses. The mean ICP of patients with acute brain injury was lower in group with 30° of head elevation than in the supine position group (mean difference [MD] - 5.58mm Hg; 95% confidence interval [CI] - 6.74 to - 4.41mm Hg; p < 0.00001). The only comparison in which a greater degree of head elevation did not significantly reduce the ICP was 45° vs. 30°. The mean CPP remained similar between 30° of head elevation and supine position (MD - 2.48mm Hg; 95% CI - 5.69 to 0.73mm Hg; p = 0.13). Similar findings were observed in all other comparisons. The mean SjvO2 was similar between the 30° of head elevation and supine position groups (MD 0.32%; 95% CI - 1.67% to 2.32%; p = 0.75), as was the mean PbtO2 (MD - 1.50mm Hg; 95% CI - 4.62 to 1.62mm Hg; p = 0.36), and the mean AVDO2 (MD 0.06µmol/L; 95% CI - 0.20 to 0.32µmol/L; p = 0.65).The mean ICP of patients with traumatic brain injury was also lower with 30° of head elevation when compared to the supine position. There was no difference in the mean values of mean arterial pressure, CPP, SjvO2, and PbtO2 between these groups. Increasing degrees of head elevation were associated, in general, with a lower ICP, whereas CPP and brain oxygenation parameters remained unchanged. The severe traumatic brain injury subanalysis found similar results.

In-situ impedance spectroscopy on copper oxide scales under potential controlled oxidation at high temperatures

In recent years, copper oxide (Cu2O) has gained significant attention for its multifaceted role as a catalyst, photocatalyst and semiconductor. Possessing a p-type conductivity and a bandgap of 2.17 eV, Cu2O emerges as an ideal candidate for applications such as water splitting and photovoltaic cells. However, to utilize its full potential, an in-depth understanding of the electrical properties of Cu2O in terms of defect density and defect mobility is required. This knowledge forms the basis for the targeted production of oxides with precisely tuned electrical properties.Extensive research on thermal oxidation under varied conditions has been performed to clarify the mechanisms governing oxide formation and growth. However, the in-situ investigation of the electrical properties of the oxide layers during their formation process is challenging.This work introduces a new method for the controlled oxidation of copper, while concurrently offering an in-depth investigation of the electrical properties of these nanometer-thick oxide layers. The implemented arrangement of potentiostat and frequency response analyzer enables their artifact-free combination. Performing HT-CV measurements in a solid electrolyte cell-setup allows to control the (potential-dependent) oxygen pressure at the copper surface. Using HT-CV, the current represents the kinetics of the redox reactions and the electric charge corresponds to the amount of substance converted. In-situ electrochemical impedance data are used to determine the electrical properties of the controlled grown layers. As a result, the defect density is obtained as a function of the oxygen partial pressure.

Coronary circulation enhances the aerobic performance of wild Pacific salmon.

Female Pacific salmon often experience higher mortality than males during their once-in-a-lifetime up-river spawning migration, particularly when exposed to secondary stressors (e.g. high temperatures). However, the underlying mechanisms remain unknown. One hypothesis is that female Pacific salmon hearts are more oxygen-limited than males and are less able to supply oxygen to the body's tissues during this demanding migration. Notably, female hearts have higher coronary blood flow, which could indicate a greater reliance on this oxygen source. Oxygen limitations can develop from naturally occurring coronary blockages (i.e., coronary arteriosclerosis) found in mature salmon hearts. If female hearts rely more heavily on coronary blood flow but experience similar arteriosclerosis levels as males, they will have disproportionately impaired aerobic performance. To test this hypothesis, we measured resting (RMR) and maximum metabolic rate (MMR), aerobic scope (AS) and acute upper thermal tolerance in coho salmon (Oncorhynchus kisutch) with an intact or artificially blocked coronary oxygen supply. We also assessed venous blood oxygen and chemistry (cortisol, ions, and metabolite concentrations) at different time intervals during recovery from exhaustive exercise. We found that coronary blockage impaired MMR, AS, and the partial pressure of oxygen in venous blood (PvO2) during exercise recovery but did not differ between sexes. Coronary ligation lowered acute upper thermal tolerance by 1.1°C. Though we did not find evidence of enhanced female reliance on coronary supply, our findings highlight the importance of coronary blood supply for mature wild salmon, where migration success may be linked to cardiac performance, particularly during warm water conditions.

TcPO2 changes are more pronounced than SpO2 changes during simulated altitude changes in a hypobaric oxygen chamber: a nonrandomized controlled trial

Abstract Background Hypoxia is a significant risk factor of hypertension. However, no studies have used transcutaneous tissue partial pressure of oxygen (TcPO2) and partial pressure of carbon dioxide (TcPCO2) monitors to measure the respective partial pressures in healthy individuals. Oxygen saturation (SpO2) is often used for traditional monitoring of vital signs. This study investigated the changes in TcPO2 and SpO2 values during rapid changes in altitude. The trial was registered at ClinicalTrials.gov (registration no. NCT06076057). Methods Healthy adult volunteers were instructed to sit vertically in a hypobaric oxygen chamber, which ascended from 0 m to 2500 m at a uniform speed within 10 min. The Danish Radiometer TCM4 was used to measure TcPO2 and TcPCO2 with the ventral side of the upper arm as the measurement site. The Shenzhen Kerokan P0D-1 W pulse oximeter was used to measure heart rate and SpO2, with values recorded once every 500 m. Results Altogether, 49 healthy volunteers were recruited between March 2023 and August 2023. With increasing altitude, TcPO2 and SpO2 decreased significantly (P &lt; 0.01). During the ascent from 0 m, TcPO2 began to change statistically at 500 m (P &lt; 0.05), whereas SpO2 began to change statistically at 1000 m (P &lt; 0.05). At the same altitude, the difference in TcPO2 was greater than the difference in SpO2. At 1000 m, there were statistically significant changes in TcPO2 and SpO2 (P &lt; 0.001). At altitudes &gt;500 m, statistical significance was identified between TcPO2 in both sexes (P &lt; 0.05). Statistical significance in TcPCO2 and heart rate was observed at the different elevations (P &lt; 0.05). Conclusion In acutely changing low-pressure hypoxic environments, TcPO2 changed more dramatically than SpO2.

Comparison of Intercostal and Subxiphoid Left Pleural Drain After Coronary Artery Bypass Grafting (CABG) Surgery: A Systematic Review and Meta-Analysis.

Coronary artery bypass grafting (CABG), a prevalent surgery for coronary artery disease, often involves left internal mammary artery harvesting, necessitating left pleural drain insertion. This can lead to pain, discomfort, and respiratory issues. This analysis compares outcomes between subxiphoid and intercostal left pleural drain insertion. Following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, this systematic review and meta-analysis involved searches in MEDLINE, Cochrane Central Register of Controlled Trials (CENTRAL), Scopus, Google Scholar, and Clinical Trial Registry. Studies were selected based on primary outcomes (postoperative ventilator support duration and pain score) and secondary outcomes (percentage predicted vital capacity (VC), forced VC (FVC), and partial pressure of oxygen (PO2) in arterial blood gas (ABG) analysis). Statistical analysis used a random effect model, pooled risk ratio, and I2 heterogeneity. Nine studies (seven randomized and two nonrandomized) with 412 patients met the inclusion criteria. Pooled analysis indicated reduced ventilation time and postoperative pain with the subxiphoid drain compared to the intercostal drain. Spirometry parameters showed improved VC, FVC, and PO2 in ABG analysis. This meta-analysis suggests that subxiphoid pleural drain insertion in CABG patients is associated with shorter ventilation times, lower pain scores, and improved pulmonary function compared to intercostal drain placement.

Resting diffusing capacity and severity of radiographic disease predict gas exchange abnormalities with exercise in former US coal miners.

The US Department of Labor (DOL) does not fund diffusing capacity (DLCO) or metabolic measurements from cardiopulmonary exercise testing (CPET) for coal miners' disability evaluations. Although exercise arterial blood gas testing is covered, many miners are unable to perform maximal tests, and sampling at peak exercise can be challenging. We explored the relationship between resting DLCO, radiographic disease severity, and CPET abnormalities in former US coal miners. We analyzed data from miners evaluated between 2005 and 2015. Multivariable linear and logistic regression analyses were used to examine relationships between percent predicted (pp) forced expiratory volume in 1 s (FEV1pp), DLCOpp, VO2maxpp, A-a oxygen gradient (A-a)pp, dead space fraction (Vd/Vt), disabling oxygen tension (PO2), and radiographic findings of pneumoconiosis. Data from 2015 male coal miners was analyzed. Mean tenure was 28 years (SD 8.6). Thirty-twopercent had an abnormal A-a gradient (>150 pp), 20% had elevated Vd/Vt (>0.33), and 34% a VO2max < 60 pp. DLCOpp strongly predicted a disabling PO2, with an odds ratio (OR) of 2.33 [2.09-2.60], compared to 1.18 [1.08-1.29] for FEV1. Each increase in subcategory of small opacity (simple) pneumoconiosis increased the odds of a disabling PO2 by 42% [1.29-1.57], controlling for age, body mass index, pack-years of tobacco smoke exposure, and years of coal mine employment. DLCO is the best resting pulmonary function test predictor of CPET abnormalities. Radiographic severity of pneumoconiosis was also associated with CPET abnormalities. These findings support funding DLCO testing for impairment and suggest the term "small opacity" should replace "simple" pneumoconiosis to reflect significant associations with impairment.

Description of mitochondrial oxygen tension and its variability in healthy volunteers.

Describing mitochondrial oxygenation (mitoPO2) and its within- and between-subject variability over time after 5-aminolevulinic acid (ALA) plaster application in healthy volunteers. Prospective cohort study. Measurements were performed in Leiden University Medical Center, the Netherlands. Healthy volunteers enrolled from July to September 2020. Two ALA plasters were placed parasternal left and right, with a 3-hour time interval, to examine the influence of the calendar time on the value of mitoPO2. We measured mitoPO2 at 4, 5, 7, 10, 28, and 31 hours after ALA plaster 1 application, and at 4, 5, 7, 25, and 28 hours after ALA plaster 2 application. At each time point, five mitoPO2 measurements were performed. Within-subject variability was defined as the standard deviation (SD) of the mean of five measurements per timepoint of a study participant. The between-subject variability was the SD of the mean mitoPO2 value of the study population per timepoint. In 16 completed inclusions, median mitoPO2 values and within-subject variability were relatively similar over time at all time points for both plasters. An increase in overall between-subject variability was seen after 25 hours ALA plaster time (19.6 mm Hg vs 23.9 mm Hg after respectively 10 and 25 hours ALA plaster time). The mitoPO2 values and within-subject variability remained relatively stable over time in healthy volunteers. An increase in between-subject variability was seen after 25 hours ALA plaster time warranting replacement of the ALA plaster one day after its application. ClinicalTrials.gov with trial number NCT04626661.

Redox Stability and Electrical Properties of a Series of Novel Quadruple Dopant BIMEVOX: Bi2V1−4x(CuNiNbTi)xO5.5−δ

Bi2VO5.5‐based materials are well‐known oxide ion conductors owing to their exceptionally high ionic conductivity. However, their poor phase and redox stabilities under a reducing atmosphere hinder their practical application as electrolytes for solid oxide fuel cells. Here, a series of novel quadruple metal‐doped bismuth vanadium system materials Bi2V1−4x(CuNiNbTi)xO5.5−δ (0 ≤ x ≤ 0.1) are prepared through a traditional solid state reaction method, aiming to enhance the phase and redox stability under reducing atmosphere. The results reveal that multiple‐metal‐doping can stabilize the tetragonal phase of Bi2VO5.5 to room temperature and show good phase and structural stabilities under inert or high oxygen partial pressure atmospheres, as well as pure oxide ion conduction which is slightly lower than that of the parent material. However, under a reducing environment, the Bi2V1−4x(CuNiNbTi)xO5.5−δ materials would still undergo a phase decomposition, yielding elemental bismuth impurity, and introducing strong electronic conduction. Thus, how to improve the phase and redox stabilities under the reducing atmosphere of the Bi2VO5.5‐based materials is still the endeavor direction in the future.

Clinical prediction for surgical versus nonsurgical interventions in patients with vertebral osteomyelitis and discitis.

Vertebral osteomyelitis and discitis (VOD), an infection of intervertebral discs, often requires spine surgical intervention and timely management to prevent adverse outcomes. Our study aims to develop a machine learning (ML) model to predict the indication for surgical intervention (during the same hospital stay) versus nonsurgical management in patients with VOD. This retrospective study included adult patients (≥18 years) with VOD (ICD-10 diagnosis codes M46.2,3,4,5) treated at a single institution between 01/01/2015 and 12/31/2019. The primary outcome studied was surgery. Candidate predictors were age, sex, race, Elixhauser comorbidity index, first-recorded lab values, first-recorded vital signs, and admit diagnosis. After splitting the dataset, XGBoost, logistic regression, and K-neighbor classifier algorithms were trained and tested for model development. A total of 1,111 patients were included in this study, among which 30% (n=339) of patients underwent surgical intervention. Age and sex did not significantly differ between the two groups; however, race did significantly differ (P<0.0001), with the surgical group having a higher percentage of white patients. The top ten model features for the best-performing model (XGBoost) were as follows (in descending order of importance): admit diagnosis of fever, negative culture, Staphylococcus aureus culture, partial pressure of arterial oxygen to fractional inspired oxygen ratio (PaO2:FiO2), admit diagnosis of intraspinal abscess and granuloma, admit diagnosis of sepsis, race, troponin I, acid-fast bacillus culture, and alveolar-arterial gradient (A-a gradient). XGBoost model metrics were as follows: accuracy =0.7534, sensitivity =0.7436, specificity =0.7586, and area under the curve (AUC) =0.8210. The XGBoost model reliably predicts the indication for surgical intervention based on several readily available patient demographic information and clinical features. The interpretability of a supervised ML model provides robust insight into patient outcomes. Furthermore, it paves the way for the development of an efficient hospital resource allocation instrument, designed to guide clinical suggestions.

Clinical Characteristics of 427 Unvaccinated Chinese Adult Patients with Maintenance Hemodialysis Infected with the SARS-CoV-2 Omicron Variant: A Retrospective Study

Background: Maintenance hemodialysis (MHD) patients constitute a distinctive population characterized by unique traits, such as hemodialysis-related immune disturbances, and increased vulnerability to infections, heart failure, particularly severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Despite considerable research on MHD patients with coronavirus disease 2019 (COVID-19), there is limited information available on the clinical characteristics and outcomes of unvaccinated adult MHD patients infected with the SARS-CoV-2 Omicron variant. Methods: A retrospective investigation was conducted in a cohort of 427 unvaccinated MHD patients diagnosed with SARS-CoV-2 Omicron infection. The clinical symptoms, laboratory results, and treatment regimens were comprehensively examined. Multivariate regression identified independent risk factors for disease severity, and two-month follow-up assessments were conducted. Results: The cohort exhibited a spectrum of disease severity, with 37.5% classified as mild, 35.3% as common, 22.5% as severe, and 4.7% as critical. Serum C-reactive protein level, procalcitonin level, and bicarbonate concentration are related to the severity of the disease. Tailored treatment strategies—including nutritional support, hemodialysis management, anti-bacterial interventions, and more—were implemented. There was a 5.6% mortality rate, with a higher prevalence of deaths in the critical subtype. Independent risk factors for disease severity included fever, age, cycle threshold values (Ct values) of ORF1ab gene, and arterial oxygen partial pressure. Follow-up assessments revealed a median duration of 11 days for the negative nucleic acid of SARS-CoV-2. Twelve patients presented a second positive ORF1ab gene during follow-up but remained asymptomatic. Conclusion: These findings suggest the intricate clinical characteristics and outcomes of MHD patients with the SARS-CoV-2 Omicron infection. Tailored treatment strategies, continuous surveillance, and understanding prognostic factors are imperative for managing this high-risk population. Further research is warranted to validate these findings.

Acute Brain Injury Risk Prediction Models in Venoarterial Extracorporeal Membrane Oxygenation Patients with Tree-Based Machine Learning: An ELSO Registry Analysis

ObjectiveWe aimed to determine if machine learning (ML) can predict acute brain injury (ABI) and identify modifiable risk factors for ABI in venoarterial extracorporeal membrane oxygenation (VA-ECMO) patients. MethodsWe included adults (≥18 years) receiving VA-ECMO or extracorporeal cardiopulmonary resuscitation (ECPR) in the Extracorporeal Life Support Organization Registry (2009-2021). Our primary outcome was ABI: central nervous system (CNS) ischemia, intracranial hemorrhage (ICH), brain death, and seizures. We utilized Random Forest, CatBoost, LightGBM and XGBoost ML algorithms (10-fold leave-one-out cross-validation) to predict and identify features most important for ABI. We extracted 65 total features: demographics, pre-ECMO/on-ECMO laboratory values, and pre-ECMO/on-ECMO settings. ResultsOf 35,855 VA-ECMO (non-ECPR) patients (median age=57.8 years, 66%=male), 7.7% (n=2,769) experienced ABI. In VA-ECMO (non-ECPR), the area under the receiver-operator characteristics curves (AUC-ROC) to predict ABI, CNS ischemia, and ICH was 0.67, 0.67, and 0.62, respectively. The true positive, true negative, false positive, false negative, positive, and negative predictive values were 33%, 88%, 12%, 67%, 18%, and 94%, respectively for ABI. Longer ECMO duration, higher 24h ECMO pump flow, and higher on-ECMO PaO2 were associated with ABI. Of 10,775 ECPR patients (median age=57.1 years, 68%=male), 16.5% (n=1,787) experienced ABI. The AUC-ROC for ABI, CNS ischemia, and ICH was 0.72, 0.73, and 0.69, respectively. Longer ECMO duration, older age, and higher 24h ECMO pump flow were associated with ABI. ConclusionsIn the largest study predicting neurological complications with ML in ECMO, longer ECMO duration and higher 24h pump flow were associated with ABI in non-ECPR and ECPR VA-ECMO.

Accelerated oxidation of epoxy thermosets with increased O2 pressure

Polymer oxidation is usually accelerated with temperature, which is therefore applied in nearly every experimental approach dealing with predictive materials aging. Because of this simple approach, we may tend to neglect that the effective concentration of oxygen also acts as a rate multiplier for oxidation. Increasing the oxygen partial pressure in an aging environment accelerates oxidation, and while there is often a near proportional increase initially, the effect of additional oxygen usually transitions to a saturation level at some elevated pressure. This has been theoretically described in the general autoxidation scheme and is well recognized. However, for many materials the exact rate behavior under moderately increased oxygen concentration remains to be established. We therefore review epoxy oxidation and offer a broader overview of its behavior under increased O2 partial pressure. Experimental data are given for a few thermoset materials demonstrating their rate behavior under O2 partial pressure up to 4 atm, meaning approximately 20 times more than under standard atmospheric conditions. Confirmative evidence suggests that epoxy materials will reach saturation oxidation rates only at significantly higher O2 partial pressure. In such a high-pressure regime it is theoretically possible to not only accelerate oxidation, but to transition into a condition where O2 diffusion can be increased without further accelerating the oxidation rate. This can reduce diffusion limited oxidation effects under specific accelerated aging conditions as a combination of temperature and O2 partial pressure.

Association of Arterial Carbon Dioxide Tension Following In-Hospital Cardiac Arrest With Survival and Favorable Neurologic Outcome.

In-hospital cardiac arrest (IHCA) continues to be associated with high morbidity and mortality. The objective of this study was to study the association of arterial carbon dioxide tension (PaCO2) on survival to discharge and favorable neurologic outcomes in adults with IHCA. The study population included 353 adults who underwent resuscitation from 2011 to 2019 for IHCA at an academic tertiary care medical center with arterial blood gas testing done within 24 hours of arrest. Outcomes of interest included survival to discharge and favorable neurologic outcome, defined as Glasgow outcome score of 4-5. Of the 353 patients studied, PaCO2 classification included: hypocapnia (PaCO2 <35 mm Hg, n = 89), normocapnia (PaCO2 35-45 mm Hg, n = 151), and hypercapnia (PaCO2 >45 mm Hg, n = 113). Hypercapnic patients were further divided into mild (45 mm Hg < PaCO2 ≤55 mm Hg, n = 62) and moderate/severe hypercapnia (PaCO2 > 55 mm Hg, n = 51). Patients with normocapnia had the highest rates of survival to hospital discharge (52.3% vs. 32.6% vs. 30.1%, P < 0.001) and favorable neurologic outcome (35.8% vs. 25.8% vs. 17.9%, P = 0.005) compared those with hypocapnia and hypercapnia respectively. In multivariable analysis, compared to normocapnia, hypocapnia [odds ratio (OR), 2.06; 95% confidence interval (CI), 1.15-3.70] and hypercapnia (OR, 2.67; 95% CI, 1.53-4.66) were both found to be independently associated with higher rates of in-hospital mortality. Compared to normocapnia, while mild hypercapnia (OR, 2.53; 95% CI, 1.29-4.97) and moderate/severe hypercapnia (OR, 2.86; 95% CI, 1.35-6.06) were both independently associated with higher in-hospital mortality compared to normocapnia, moderate/severe hypercapnia was also independently associated with lower rates of favorable neurologic outcome (OR, 0.28; 95% CI, 0.11-0.73), while mild hypercapnia was not. In this prospective registry of adults with IHCA, hypercapnia noted within 24 hours after arrest was independently associated with lower rates of survival to discharge and favorable neurologic outcome.

Variability of Resting Carbon Dioxide Tension in Patients with Intracranial Steno-occlusive Disease.

Introduction Controlling the partial pressure of carbon dioxide (PaCO 2 ) is an important consideration in patients with intracranial steno-occlusive disease to avoid reductions in critical perfusion from vasoconstriction due to hypocapnia, or reductions in blood flow due to steal physiology during hypercapnia. However, the normal range for resting PCO 2 in this patient population is not known. Therefore, we investigated the variability in resting end-tidal PCO 2 (P ET CO 2 ) in patients with intracranial steno-occlusive disease and the impact of revascularization on resting P ET CO 2 in these patients. Setting and Design Tertiary care center, retrospective chart review Materials and Methods We collected resting P ET CO 2 values in adult patients with intracranial steno-occlusive disease who presented to our institution between January 2010 and June 2021. We also explored postrevascularization changes in resting P ET CO 2 in a subset of patients. Results Two hundred and twenty-seven patients were included [moyamoya vasculopathy ( n = 98) and intracranial atherosclerotic disease ( n = 129)]. In the whole cohort, mean ± standard deviation resting P ET CO 2 was 37.8 ± 3.9 mm Hg (range: 26-47). In patients with moyamoya vasculopathy and intracranial atherosclerotic disease, resting P ET CO 2 was 38.4 ± 3.6 mm Hg (range: 28-47) and 37.4 ± 4.1 mm Hg (range: 26-46), respectively. A trend was identified suggesting increasing resting P ET CO 2 after revascularization in patients with low preoperative resting P ET CO 2 (<38 mm Hg) and decreasing resting P ET CO 2 after revascularization in patients with high preoperative resting P ET CO 2 (>38 mm Hg). Conclusion This study demonstrates that resting P ET CO 2 in patients with intracranial steno-occlusive disease is highly variable. In some patients, there was a change in resting P ET CO 2 after a revascularization procedure.

Embryos from Prepubertal Hyperglycemic Female Mice Respond Differentially to Oxygen Tension In Vitro.

Reduced oxygen during embryo culture in human ART prevents embryo oxidative stress. Oxidative stress is also the major mechanism by which maternal diabetes impairs embryonic development. This study employed induced hyperglycemia prepubertal mice to mimic childhood diabetes to understand the effects of varying oxygen tension during in vitro embryonic development. The oocytes were fertilized and cultured at low (≈5%) oxygen (LOT) or atmospheric (≈20%) oxygen tension (HOT) for up to 96 h. Embryo development, apoptosis in blastocysts, inner cell mass (ICM) outgrowth proliferation, and Hif1α expression were assessed. Though the oocyte quality and meiotic spindle were not affected, the fertilization rate (94.86 ± 1.18 vs. 85.17 ± 2.81), blastocyst rate (80.92 ± 2.92 vs. 69.32 ± 2.54), and ICM proliferation ability (51.04 ± 9.22 vs. 17.08 ± 3.05) of the hyperglycemic embryos were significantly higher in the LOT compared to the HOT group. On the other hand, blastocysts from the hyperglycemic group, cultured at HOT, had a 1.5-fold increase in apoptotic cells compared to the control and lower Hif1α transcripts in ICM outgrowths compared to the LOT. Increased susceptibility of embryos from hyperglycemic mice to higher oxygen tension warrants the need to individualize the conditions for embryo culture systems in ART clinics, particularly when an endogenous maternal pathology affects the ovarian environment.

Relationship between the Thermodynamic Quantities and Coordination Structure of Oxide Ions in CaCl2-Based Chloride Melts.

Measuring the thermodynamic quantities and coordination structure of oxide ions in CaCl2-based melts is essential for comprehensively understanding the relationship between the thermodynamic and microscopic behaviors of high-temperature molten salts. In this study, the standard formal chemical potentials of oxide ion, μO2- o', and activity coefficient, γO2- , in NaCl-CaCl2, NaCl-KCl-CaCl2, and LiCl-KCl-CaCl2 melts at 873 K, were evaluated by measuring the dependence of potential of O2/O2- on the oxygen partial pressure by using non-consumable ceramic electrodes; the μO2- o' was -527 ± 0.3, - 535 ± 0.1, and -538 ± 0.2 kJ mol-1 and the γO2- was 0.10, 0.30, and 0.45 for each melt. In addition, the coordination structure of oxide ions in each melt was investigated by combining high-temperature Raman spectroscopy and density functional theory calculations. The coordination structures of oxide ions were identified as [NaO2]3- and [CaOCl3]3- in the NaCl-CaCl2 melt, [CaOCl2]2- in the NaCl-KCl-CaCl2 melt, and [LiCaO]+ and [Li3KO]2+ in the LiCl-KCl-CaCl2 melt, revealing that the stable structure was significantly different depending on the melt composition. The activity coefficients showed a tendency to depend on the nearest-neighbor cation coordinated with the oxide ion. The reported data will provide insights into the physicochemical properties of high-temperature melts and contribute to controlling the compatibility of materials and melts in pyrochemical engineering processes.

The association of arterial partial oxygen pressure with mortality in critically ill sepsis patients: a nationwide observational cohort study

BackgroundAlthough several trials were conducted to optimize the oxygenation range in intensive care unit (ICU) patients, no studies have yet reached a universal recommendation on the optimal a partial pressure of oxygen in arterial blood (PaO2) range in patients with sepsis. Our aim was to evaluate whether a relatively high arterial oxygen tension is associated with longer survival in sepsis patients compared with conservative arterial oxygen tension.MethodsFrom the Korean Sepsis Alliance nationwide registry, patients treated with liberal PaO2 (PaO2 ≥ 80 mm Hg) were 1:1 matched with those treated with conservative PaO2 (PaO2 < 80 mm Hg) over the first three days after ICU admission according to the propensity score. The primary outcome was 28-day mortality.ResultsThe median values of PaO2 over the first three ICU days in 1211 liberal and 1211 conservative PaO2 groups were, respectively, 107.2 (92.0–134.0) and 84.4 (71.2–112.0) in day 1110.0 (93.4–132.0) and 80.0 (71.0–100.0) in day 2, and 106.0 (91.9–127.4) and 78.0 (69.0–94.5) in day 3 (all p-values < 0.001). The liberal PaO2 group showed a lower likelihood of death at day 28 (14.9%; hazard ratio [HR], 0.79; 95% confidence interval [CI] 0.65–0.96; p-value = 0.017). ICU (HR, 0.80; 95% CI 0.67–0.96; p-value = 0.019) and hospital mortalities (HR, 0.84; 95% CI 0.73–0.97; p-value = 0.020) were lower in the liberal PaO2 group. On ICU days 2 (p-value = 0.007) and 3 (p-value < 0.001), but not ICU day 1, hyperoxia was associated with better prognosis compared with conservative oxygenation., with the lowest 28-day mortality, especially at PaO2 of around 100 mm Hg.ConclusionsIn critically ill patients with sepsis, higher PaO2 (≥ 80 mm Hg) during the first three ICU days was associated with a lower 28-day mortality compared with conservative PaO2.

Utility of Clinical Variables for Deciding Palliative Care in Paraquat Poisoning: A Retrospective Study.

Patients with paraquat poisoning (PP) have a mortality rate comparable to that of advanced malignancies, yet palliative care is seldom considered in these patients. This audit aimed to identify triggers for early palliative care referral in critically ill patients with PP. Medical records of patients with PP were audited. Predictors of mortality within 48 hours of hospitalization and 24 hours of intensive care unit (ICU) admission were considered as triggers for palliative care referral. Among 108 patients, 84 complete records were analyzed, and 53 out of 84 (63.1%) expired. Within 48 hours after hospitalization, the lowest oxygen partial pressure in arterial blood to a fraction of inspired oxygen [the ratio of partial pressure of oxygen in arterial blood (PaO2) to the fraction of inspiratory oxygen concentration (FiO2) (PaO2/FiO2)] was the independent predictor of mortality, cut-off ≤ 197; the area under the curve (AUC), 0.924; sensitivity, 97%; specificity, 78%; p <0.001; and 95% confidence interval (CI): 0.878-0.978. Kaplan-Meier survival plot showed that the mean survival time of patients with the lowest PaO2/FiO2, ≤197, was 4.64 days vs 17.20 days with PaO2/FiO2 >197 (log-rank p < 0.001). Sequential organ failure assessment (SOFA) score within 24 hours of ICU admission had a cut-off ≥9; AUC, 0.980; p < 0.001; 95% CI: 0.955-1.000; 91% sensitivity; and 90% specificity for mortality prediction. Out of the total of 84 patients with PP analyzed, there were 11 patients admitted to the high dependency units (13.1%) and 73 patients admitted to the ICU (86.9%). Out of the total of 84 patients of PP in whom data was analyzed, 53 (63.1%) patients required ventilator support. All the 53 patients who required ventilator support due to worsening hypoxemia, eventually expired. The lowest PaO2/FiO2 ≤ 197 within 48 hours of hospitalization, SOFA score ≥9 within 24 hours of ICU admission or need for mechanical ventilation are predictors of mortality in PP patients, who might benefit from early palliative care. Rao S, Maddani SS, Chaudhuri S, Bhatt MT, Karanth S, Damani A, et al. Utility of Clinical Variables for Deciding Palliative Care in Paraquat Poisoning: A Retrospective Study. Indian J Crit Care Med 2024;28(5):453-460.