Suppressing the Shuttle Effect via Polypyrrole-Coated Te Nanotubes for Advanced Na-Te Batteries.

There is a growing demand for research and development of advanced energy storage devices with high energy density utilizing earth-abundant metal anodes such as sodium metal. Tellurium, a member of the chalcogen group, stands out as a promising cathode material due to its remarkable volumetric capacity, comparable to sulfur, and significantly high electrical conductivity. However, critical issues arise from soluble sodium polytellurides, leading to the shuttle effect. This phenomenon can result in the loss of active materials, self-discharge, and anode instability. Here, we introduce polypyrrole-coated tellurium nanotubes as the cathode materials, where polypyrrole plays a crucial role in preventing the dissolution of polytellurides, as confirmed through operando optical microscopy. The polypyrrole-coated tellurium nanotubes exhibited an outstanding rate performance and long cycle stability in sodium-tellurium batteries. These research findings are anticipated to bolster the viability of polypyrrole-coated tellurium nanotubes as promising cathode materials, making a substantial contribution to the commercialization of sodium-ion battery technology.

High Mobility Transistors and Flexible Optical Synapses Enabled by Wafer-Scale Chemical Transformation of Pt-Based 2D Layers.

Electronic devices employing two-dimensional (2D) van der Waals (vdW) transition-metal dichalcogenide (TMD) layers as semiconducting channels often exhibit limited performance (e.g., low carrier mobility), in part, due to their high contact resistances caused by interfacing non-vdW three-dimensional (3D) metal electrodes. Herein, we report that this intrinsic contact issue can be efficiently mitigated by forming the 2D/2D in-plane junctions of 2D semiconductor channels seamlessly interfaced with 2D metal electrodes. For this, we demonstrated the selectively patterned conversion of semiconducting 2D PtSe2 (channels) to metallic 2D PtTe2 (electrodes) layers by employing a wafer-scale low-temperature chemical vapor deposition (CVD) process. We investigated a variety of field-effect transistors (FETs) employing wafer-scale CVD-2D PtSe2/2D PtTe2 heterolayers and identified that silicon dioxide (SiO2) top-gated FETs exhibited an extremely high hole mobility of ∼120 cm2 V-1 s-1 at room temperature, significantly surpassing performances with previous wafer-scale 2D PtSe2-based FETs. The low-temperature nature of the CVD method further allowed for the direct fabrication of wafer-scale arrays of 2D PtSe2/2D PtTe2 heterolayers on polyamide (PI) substrates, which intrinsically displayed optical pulse-induced artificial synaptic behaviors. This study is believed to vastly broaden the applicability of 2D TMD layers for next-generation, high-performance electronic devices with unconventional functionalities.

Predicting cerebrovascular age and its clinical relevance: Modeling using 3D morphological features of brain vessels.

Aging manifests as many phenotypes, among which age-related changes in brain vessels are important, but underexplored. Thus, in the present study, we constructed a model to predict age using cerebrovascular morphological features, further assessing their clinical relevance using a novel pipeline. Age prediction models were first developed using data from a normal cohort (n = 1181), after which their relevance was tested in two stroke cohorts (n = 564 and n = 455). Our novel pipeline adapted an existing framework to compute generic vessel features for brain vessels, resulting in 126 morphological features. We further built various machine learning models to predict age using only clinical factors, only brain vessel features, and a combination of both. We further assessed deviation from healthy aging using the age gap and explored its clinical relevance by correlating the predicted age and age gap with various risk factors. The models constructed using only brain vessel features and those combining clinical factors with vessel features were better predictors of age than the clinical factor-only model (r = 0.37, 0.48, and 0.26, respectively). Predicted age was associated with many known clinical factors, and the associations were stronger for the age gap in the normal cohort. The age gap was also associated with important factors in the pooled cohort atherosclerotic cardiovascular disease risk score and white matter hyperintensity measurements. Cerebrovascular age, computed using the morphological features of brain vessels, could serve as a potential individualized marker for the early detection of various cerebrovascular diseases.

Protective Effects of Changbudodam-tang on Cell Death Signals on the Bone Marrow-Derived Human Mesenchymal Stem Cells via Regulation of MKK7/JNK/c-Jun Signaling Pathway.

Objectives: Polycystic ovary syndrome (PCOS) is one of the most common disorders and it shows up to 20% prevalence in reproductive-aged women populations, but no cures are available to date. We aimed to investigate the protective effects of Changbudodam-tang (CBD) on cell death signaling pathways, inflammation, and oxidative stress observed in Bone-Marrow derived human mesenchymal stem cell (BM-hMSC) by means of PCOS therapeutics in the future. Methods: BM-hMSCs were applied with cell deaths and injuries. Apoptosis and pyroptosis signals were quenched with their related signaling pathways using quantitative PCR, Western blot, and fluorescence image analysis. Results: Our data clearly displayed hydrogen peroxide- and nigericin-treated cell death signaling pathways via regulations of mitochondrial integrity and interleukin (IL)-1ß at the cellular levels (p < 0.01 or 0.001). We further observed that pre-treatment with CBD showed protective effects against oxidative stress by enhancement of antioxidant components at the cellular level, with respect to both protein and mRNA expression levels (p < 0.05, 0.01 or 0.001). The mechanisms of CBD were examined by Western blot analysis, and it showed anti-cell death, anti-inflammatory, and antioxidant effects via normalizations of the Jun N-terminal kinase/mitogen-activated protein kinase kinase 7/c-Jun signaling pathways. Conclusion: This study confirmed the pharmacological properties of CBD by regulation of cellular oxidation and the inflammation-provoked cell death condition of BM-hMSCs, which is mediated by the MKK7/JNK/c-Jun signaling pathway.

Risk of Cardiovascular Events Associated with Chronic Obstructive Pulmonary Disease and/or Metabolic Syndrome: A Large-Scale Nationwide Population-Based Cohort Study.

Purpose: Chronic obstructive pulmonary disease (COPD) and metabolic syndrome (MetS) are among the most prevalent conditions that might predispose individuals to life-threatening events. We aimed to examine their associations with cardiovascular (CV) events and mortality using a large-scale population dataset from the National Health Information Database in Korea. Patients and Methods: This population-based cohort study enrolled adults aged ≥40 years who had undergone more than two health examinations between 2009 and 2011. They were divided into four groups based on the presence of COPD and MetS. Analysis of the outcomes and CV events or deaths was performed from 2014 to 2019. We compared CV event incidence and mortality rates using a multivariate Cox proportional hazards model and Kaplan-Meier curves. Results: Totally, 5,101,810 individuals were included, among whom 3,738,458 (73.3%) had neither COPD nor MetS, 1,193,014 (23.4%) had only MetS, 125,976 (2.5%) had only COPD, and 44,362 (0.9%) had both. The risk of CV events was significantly higher in individuals with both COPD and MetS than in those with either COPD or MetS alone (HRs: 2.4 vs 1.6 and 1.8, respectively; all P <0.001). Similarly, among those with both COPD and MetS, all-cause and CV mortality risks were also elevated (HRs, 2.9 and 3.0, respectively) compared to the risks in those with either COPD (HRs, 2.6 and 2.1, respectively) or MetS (HRs, 1.7 and 2.1, respectively; all P <0.001). Conclusion: The comorbidity of MetS in patients with COPD increases the incidence of CV events and all-cause and cardiovascular mortality rates.

North American Cancer Center Clinical Research Capacity and Benchmarking in the Postpandemic Era.

PURPOSE: Cancer center clinical trial offices (CCTOs) support trial development, activation, conduct, regulatory adherence, data integrity, and compliance. In 2018, the Association of American Cancer Institutes (AACI) Clinical Research Innovation (CRI) Steering Committee conducted and published survey results to benchmark North American CCTOs, including trial volume, accrual, full time equivalents (FTEs), and budget. The survey was readministered in 2023 to assess contemporary CCTO performance and capacity with results presented here. METHODS: The 28 question 2023 survey was sent to directors of AACI's clinical member cancer centers. Survey participation was voluntary, no compensation was provided, and data requested covered operations during 2022. Definitions were consistent with National Cancer Institute (NCI) CCTO reporting requirements and AACI staff anonymously compiled results for descriptive statistical reporting. RESULTS: The survey response rate was 61% (60/99). The median annual CCTO budget was $11.5 million (M) US dollars (USD) versus $8.2M USD in 2018. These budgets support a median of 150 FTEs versus 104 previously, and a median total of 384 versus 280 interventional treatment trials and a median of 479 versus 531 interventional treatment accruals. Sources of support for CCTO annual budgets were primarily from industry revenue (45.3%) or institutional support (31.7%). Nearly 60% of centers reported activating NCI-sponsored studies within 90 days but only 9% reported meeting a 90-day activation timeline for industry sponsored studies. CONCLUSION: Contemporary benchmarks for CCTO operations through this survey demonstrate larger staff sizes, larger budgets, more trials supported, but fewer patients enrolled to interventional treatment trials in comparison with 2018. These data shine a critical light on the increasing complexity of cancer clinical trials, the importance of external funding sources, and necessary operational efficiency upgrades to provide cutting-edge cancer research and care.

Enhanced Deposition Selectivity of High-k Dielectrics by Vapor Dosing and Selective Removal of Phosphonic Acid Inhibitors.

Area-selective atomic layer deposition (AS-ALD), which provides a bottom-up nanofabrication method with atomic-scale precision, has attracted a great deal of attention as a means to alleviate the problems associated with conventional top-down patterning. In this study, we report a methodology for achieving selective deposition of high-k dielectrics by surface modification through vapor-phase functionalization of octadecylphosphonic acid (ODPA) inhibitor molecules accompanied by post-surface treatment. A comparative evaluation of deposition selectivity of ZrO2 thin films deposited with the O2 and O3 reactants was performed on SiO2, TiN, and W substrates, and we confirmed that high enough deposition selectivity over 10 nm can be achieved even after 200 cycles of ALD with the O2 reactant. Subsequently, the electrical properties of ZrO2 films deposited with O2 and O3 reactants were investigated with and without post-deposition treatment. We successfully demonstrated that high-quality ZrO2 thin films with high dielectric constants and stable antiferroelectric properties can be produced by subjecting the films to ozone, which can eliminate carbon impurities within the films. We believe that this work provides a new strategy to achieve highly selective deposition for AS-ALD of dielectric on dielectric (DoD) applications toward upcoming bottom-up nanofabrication.

Risk factors for chloral hydrate sedation failure in pediatric patients: a retrospective analysis.

Background: This study aimed to investigate the risk factors for chloral hydrate sedation failure and complications in a tertiary children's hospital in South Korea. Methods: A retrospective analysis of pediatric procedural sedation with chloral hydrate between January 1, 2021, and March 30, 2022, was performed. The collected data included patient characteristics, sedation history, and procedure. Multivariable regression analysis was performed to identify the risk factors for procedural sedation failure and complications. Results: A total of 6691 procedural sedation were included in the analysis; sedation failure following chloral hydrate (50 mg/kg) occurred in 1457 patients (21.8%) and was associated with a higher rate of overall complications compared to those with successful sedation (17.5% [225 / 1457] vs. 6.2% [322 / 5234]; P < 0.001; odds ratio, 3.236). In the multivariable regression analysis, the following factors were associated with increased risk of sedation failure: general ward or intensive care unit inpatient (compared with outpatient); congenital syndrome; oxygen dependency; history of sedation failure or complications with chloral hydrate; procedure more than 60 min; and magnetic resonance imaging, radiotherapy, or procedures with painful or intense stimuli (all P values < 0.05). Factors contributing to the complications included general ward inpatient, congenital syndromes, congenital heart disease, preterm birth, oxygen dependency, history of complications with chloral hydrate, and current sedation failure with chloral hydrate (all P values < 0.05). Conclusions: To achieve successful sedation with chloral hydrate, the patient's sedation history, risk factors, and the type and duration of the procedure should be considered.

Beyond Legal Boundaries: Public and Clinician Perspectives on Treatment Withdrawal in Infants With Poor Neurological Prognosis.

BACKGROUND: Despite medical advancements in neonatal survival rates, many children have poor neurological outcomes. Because the law in Korea restricts the withdrawal of life-sustaining treatment to only cases of imminent death, treatment discontinuation may not be an option, even in patients with poor neurological prognosis. This study investigated the opinions of the general population and clinicians regarding life-sustaining treatment withdrawal in such cases using hypothetical scenarios. METHODS: We conducted a cross-sectional study on the general population and clinicians using a web-based questionnaire. The sample of the general population from an online panel comprised 500 individuals aged 20-69 years selected by quota sampling. The clinician sample comprised 200 clinicians from a tertiary university hospital. We created hypothetical vignettes and questionnaire items to assess attitudes regarding mechanical ventilation withdrawal for an infant at risk of poor neurological prognosis due to birth asphyxia at 2 months and 3 years after the incidence. RESULTS: Overall, 73% of the general population and 74% of clinicians had positive attitudes toward mechanical ventilator withdrawal at 2 months after birth asphyxia. The proportion of positive attitudes toward mechanical ventilator withdrawal was increased in the general population (84%, P < 0.001) and clinicians (80.5%, P = 0.02) at 3 years after birth asphyxia. Religion, spirituality, the presence of a person with a disability in the household, and household income were associated with the attitudes of the general population. In the multivariable logistic regression analysis of the general population, respondents living with a person with a disability or having a disability were more likely to find the withdrawal of the ventilator at 2 months and 3 years after birth asphyxia not permissible. Regarding religion, respondents who identified as Christians were more likely to find the ventilator withdrawal at 2 months after birth asphyxia unacceptable. CONCLUSION: The general population and clinicians shared the perspective that the decision to withdraw life-sustaining treatment in infants with a poor neurological prognosis should be considered before the end of life. A societal discussion about making decisions centered around the best interest of pediatric patients is warranted.

Enhancing the Diagnostic Yield of Esophageal Manometry Using Distension Contraction Plots of Peristalsis & Artificial Intelligence.

BACKGROUND: Our prior study reveal that the distension-contraction profiles using high-resolution manometry impedance (HRMZ) recordings can distinguish patients with dysphagia symptom but normal esophageal function testing ("functional dysphagia") from controls. AIMS: To determine the diagnostic value of the recording protocol used in our prior studies (10cc swallows with subjects in the Trendelenburg position) against the standard clinical protocol (5cc swallows with subject in the supine position). We used advanced machine learning techniques and robust metrics for the classification purposes. METHODS: Studies were performed in 30 healthy subjects and 30 patients with functional dysphagia. A custom-built software was used to extract the relevant distension-contraction features of esophageal peristalsis. Ensemble methods, i.e., gradient boost, support vector machines (SVM), and logit boost were used as the primary machine learning algorithms. RESULTS: While the individual contraction features were marginally different between the two groups, the distension features of peristalsis were significantly different. The ROC curves values for the standard recording protocol, for the distension features ranged from 0.74 to 0.82; they were significantly better for the protocol used in our prior studies, ranged from 0.81-0.91. The ROC curve values using 3 machine learning algorithms were far superior for the distension than the contraction features of esophageal peristalsis, revealing value of 0.95 for the SVM algorithm. CONCLUSIONS: Current patient classification based on the contraction phase of peristalsis misses large number of patients who have abnormality in the distension phase of peristalsis. Distension contraction plots should be the standard of assessing esophageal peristalsis in clinical practice.

Pulmonary Artery Periadventitial Hematoma in a Patient with Aortic Intramural Hematoma: A Case Report.

A pulmonary artery periadventitial hematoma is a rare complication of a Stanford type A intramural hematoma. As the proximal ascending aorta and pulmonary artery share a common adventitial layer, extravasated blood from the intramural hematoma in the ascending thoracic aorta may extend to beneath the adventitia of the pulmonary artery. The authors describe a case involving a 66-year-old male with acute chest pain who presented with a pulmonary artery periadventitial hematoma associated with a Stanford type A intramural hematoma.

Red2Flpe-SCON: a versatile, multicolor strategy for generating mosaic conditional knockout mice.

Image-based lineage tracing enables tissue turnover kinetics and lineage potentials of different adult cell populations to be investigated. Previously, we reported a genetic mouse model system, Red2Onco, which ectopically expressed mutated oncogenes together with red fluorescent proteins (RFP). This system enabled the expansion kinetics and neighboring effects of oncogenic clones to be dissected. We now report Red2Flpe-SCON: a mosaic knockout system that uses multicolor reporters to label both mutant and wild-type cells. We develop the Red2Flpe mouse line for red clone-specific Flpe expression, as well as the FRT-based SCON (Short Conditional IntrON) method to facilitate tunable conditional mosaic knockouts in mice. We use the Red2Flpe-SCON method to study Sox2 mutant clonal analysis in the esophageal epithelium of adult mice which reveal that the stem cell gene, Sox2, is less essential for adult stem cell maintenance itself, but rather for stem cell proliferation and differentiation.

Device Closure or Antithrombotic Therapy After Cryptogenic Stroke in Elderly Patients With a High-Risk Patent Foramen Ovale.

BACKGROUND AND PURPOSE: In young patients (aged 18-60 years) with patent foramen ovale (PFO)-associated stroke, percutaneous closure has been found to be useful for preventing recurrent ischemic stroke or transient ischemic attack (TIA). However, it remains unknown whether PFO closure is also beneficial in older patients. METHODS: Patients aged ≥60 years who had a cryptogenic stroke and PFO from ten hospitals in South Korea were included. The effect of PFO closure plus medical therapy over medical therapy alone was assessed by a propensity-score matching method in the overall cohort and in those with a high-risk PFO, characterized by the presence of an atrial septal aneurysm or a large shunt. RESULTS: Out of the 437 patients (mean age, 68.1), 303 (69%) had a high-risk PFO and 161 (37%) patients underwent PFO closure. Over a median follow-up of 3.9 years, recurrent ischemic stroke or TIA developed in 64 (14.6%) patients. In the propensity score-matched cohort of the overall patients (130 pairs), PFO closure was associated with a significantly lower risk of a composite of ischemic stroke or TIA (hazard ratio [HR]: 0.45; 95% confidence interval [CI]: 0.24-0.84; P=0.012), but not for ischemic stroke. In a subgroup analysis of confined to the high-risk PFO patients (116 pairs), PFO closure was associated with significantly lower risks of both the composite of ischemic stroke or TIA (HR: 0.40; 95% CI: 0.21-0.77; P=0.006) and ischemic stroke (HR: 0.47; 95% CI: 0.23-0.95; P=0.035). CONCLUSION: Elderly patients with cryptogenic stroke and PFO have a high recurrence rate of ischemic stroke or TIA, which may be significantly reduced by device closure.

Genetic polymorphisms linked to extreme postorthodontic external apical root resorption in Koreans.

BACKGROUND: External apical root resorption (EARR) is a common undesirable outcome of orthodontic treatment, this study aimed to identify genetic polymorphisms associated with the susceptibility to extreme orthodontic-induced EARR in a Korean population using extreme phenotype analysis sampling. METHODS: Genomic DNA was isolated from the saliva of 77 patients who underwent orthodontic treatment involving two maxillary premolar extractions. The patients were divided into two groups based on EARR values measured on periapical radiographs: The significant resorption group (SG, EARR ≥ 4 mm) and the normal group (NG, EARR < 2 mm). In the NG group, patients with EARR < 1 mm were named the non-resorption group (NonG). Targeted next-generation sequencing was performed using the screened single nucleotide polymorphisms (SNPs), and firth logistic regression analysis was used to determine genetic associations with EARR. Haplotype-based association analysis was performed for specific SNPs. RESULTS: SNPs related to genes TNFSF11, TNFRSF11B, WNT3A, SFRP2, LRP6, P2RX7, and LRP1 were found to be significantly associated with severe EARR (p < 0.05, pre-Bonferroni correction p-values). Additionally, the haplotype CCA of rs17525809, rs208294, and rs1718119 P2RX7 had a higher frequency in the SG group. CONCLUSION: Extreme phenotype analysis has identified eleven SNPs related to genes TNFSF11, TNFRSF11B, WNT3A, SFRP2, LRP6, P2RX7, and LRP1 that are associated with severe root resorption in the Korean population. These findings will contribute to the development of predictive diagnostic tools for identifying severe root resorption that may occur during orthodontic treatment.

The relationship between caregivers' behaviors and resistant behaviors of persons living with dementia during personal care in long-term care facilities: A lag sequential analysis.

Many older adults living with dementia exhibit resistant behaviors. Person-centered care is the gold standard of care; however, the sequential relationship between resistant and caregiving behaviors has not been identified. This study examined the sequential relationship between caregiving and care-resistant behaviors and analyzed 68 videos of personal care encounters of 21 residents living in four long-term care facilities. The videos were coded focusing on two sequences of behavior: residents' resistant behaviors and caregivers' behaviors. Lag sequential analysis was conducted using initial-response behavior pairs (resident-caregiver behavior or caregiver-resident behavior pairs). Person-centered care led to less resistant behavior (odds ratio 0.23; 95 % confidence interval 0.16, 0.33), whereas less person-centered care was followed by resistant behaviors (odds ratio 0.42; 95 % confidence interval 0.30, 0.59). A significant sequential association was found between task-centered behavior and resistant behavior. Hence, rigorous efforts are recommended to provide person-centered care through multilevel efforts.

Usefulness of the heart rate variability test in predicting intradialytic hypotension in patients undergoing chronic haemodialysis.

Background: Intradialytic hypotension (IDH) is the primary complication of haemodialysis (HD); however, its diverse pathophysiology and inconsistent definitions complicate its prediction. Despite attempts using the heart rate variability (HRV) test for IDH prediction, studies on its usefulness for predicting IDH diagnosed per the nadir 90 criterion are lacking. We aimed to evaluate HRV test efficacy and reproducibility in predicting IDH based on the nadir 90 criterion. Methods: Seventy patients undergoing HD participated in this multicentre prospective observational study. The HRV test was performed during non-HD periods and IDH was monitored during 12 HD sessions. IDH was diagnosed according to the nadir 90 criterion, defined as a decrease in systolic blood pressure of ≤90 mmHg during HD. After monitoring, the HRV test was repeated. An HRV-IDH index was developed using multivariate logistic regression analysis employing HRV test parameters. The predictive power of the HRV-IDH index was analysed using the area under the receiver operating characteristics curve (AUROC). Reproducibility was evaluated using correlation analysis of two HRV tests on the same patient. Results: There were 37 and 33 patients in the IDH and non-IDH groups, respectively. The HRV-IDH index predicted IDH occurrence with AUROCs of 0.776 and 0.803 for patients who had experienced at least one or repeated IDH episodes, respectively. Spearman's correlation coefficient for HRV-IDH indices was 0.859 for the first and second HRV tests. Conclusions: The HRV test holds promise for predicting IDH, particularly for patients with recurring IDH diagnosed based on the nadir 90 criterion.

Bioelectrical impedance parameters add incremental value to waist-to-hip ratio for prediction of metabolic dysfunction associated steatotic liver disease in youth with overweight and obesity.

Introduction: Metabolic dysfunction-associated steatotic liver disease (MASLD) presents a growing health concern in pediatric populations due to its association with obesity and metabolic syndrome. Bioelectrical impedance analysis (BIA) offers a non-invasive and potentially effective alternative for identifying MASLD risk in youth with overweight or obesity. Therefore, this study aimed to assess the utility of BIA for screening for MASLD in the youth. Method: This retrospective, cross-sectional study included 206 children and adolescents aged <20 years who were overweight and obese. The correlations between anthropometric measurements and BIA parameters and alanine aminotransferase (ALT) levels were assessed using Pearson's correlation analysis. Logistic regression analysis was performed to examine the associations between these parameters and ALT level elevation and MASLD score. Receiver operating characteristic (ROC) curves were generated to assess the predictive ability of the parameters for MASLD. Results: Pearson's correlation analysis revealed that waist-to-hip ratio (WHR), percentage body fat (PBF), and BIA parameters combined with anthropometric measurements were correlated with ALT level. Logistic regression revealed that WHR, skeletal muscle mass/WHR, PBF-WHR, fat-free mass/WHR, and appendicular skeletal muscle mass/WHR were correlated with ALT level elevation after adjusting for age, sex, and puberty. WHR, PBF-WHR, and visceral fat area (VFA)-WHR were positively correlated with the MASLD score in the total population after adjusting for age, sex, and puberty. PBF-WHR and VFA-WHR were correlated with the MASLD score even in youth with a normal ALT level. The cutoff points and area under the ROC curves were 34.6 and 0.69 for PBF-WHR, respectively, and 86.6 and 0.79 for VFA-WHR, respectively. Discussion: This study highlights the utility of combining BIA parameters and WHR in identifying the risk of MASLD in overweight and obese youth, even in those with a normal ALT level. BIA-based screening offers a less burdensome and more efficient alternative to conventional MASLD screening methods, facilitating early detection and intervention in youth at risk of MASLD.

Atmospheric particulate matter and hypoxaemia in Korean children receiving general anaesthesia: A retrospective analysis.

BACKGROUND: The association between the concentration of atmospheric particulate matter on the day of surgery and the occurrence of intra-operative hypoxaemia in children receiving general anaesthesia is unclear. OBJECTIVE: To investigate the association between the exposure to of particulate matter on the day of surgery and the occurrence of intra-operative hypoxaemia, defined as a pulse oximetry oxygen saturation of less than 90% for more than 1 min, in children. DESIGN: Retrospective study. SETTING: Single-centre. PARTICIPANTS: Children aged 18 years or younger who received general anaesthesia between January 2019 and October 2020. INTERVENTION: Information on daily levels of particulate matter with a diameter 10 µm or less and 2.5 µm or less measured within a neighbourhood corresponding to the area defined by the hospital's zip code was obtained from publicly available air-quality data. MAIN OUTCOME MEASURES: The primary outcome was intra-operative hypoxaemia, defined as a pulse oximetry oxygen saturation of less than 90% lasting for more than 1 min, manually verified by anaesthesiologists using vital sign registry data extracted at 2 s intervals. RESULTS: Of the patients finally analysed, 3.85% (489/13 175) experienced intra-operative hypoxaemia. Higher levels of particulate matter 10 µm or less in diameter (≥81 µg m-3, 472/12 900, 3.7%) were associated with an increased occurrence of intra-operative hypoxaemia compared with lower particulate matter concentrations [<81 µg m-3, 17/275, 6.2%; adjusted odds ratio, 1.71; 95% confidence interval (CI), 1.04 to 2.83; P = 0.035]. CONCLUSION: The level of particulate matter on the day of surgery pose a risk of intra-operative hypoxaemia in children receiving general anaesthesia. If the concentrations of particulate matter 10 µm or less in diameter on the day of surgery are high, children receiving general anaesthesia should be managed with increased caution.