Search Results (685)

Antarctic krill (Euphausia superba) is a keystone species in the marine ecosystem of the Antarctic Ocean, bringing about significant ecological and economic value. The spatio-temporal distribution of Antarctic krill directly affects commercial fishing; meanwhile, changes in krill population structure play a crucial role in maintaining the balance of the Southern Ocean ecosystem. This study analyzed six years of midwater trawl data, including over 160,000 krill length measurements, to elucidate spatio-temporal dynamics and population composition, providing actionable insights for improved fishery management. Here, we reveal southward migration shifts in krill fishing grounds, with smaller individuals favoring ice-rich southern latitudes. Commercial krill fishing operations preferentially targeted high-density fishing grounds rather than selecting larger individuals. Among the catches, the age 1+ class accounted for the highest proportion at 42.80%, followed by the age 2+ class at 39.42%, with individuals ≥3+ accounting for 17.44%. Although the mean krill length experienced a decline in 2017, it demonstrated a sustained recovery in subsequent years, reaching peak dimensions in 2022. This maximum-growth year also exhibited the highest proportion (12.6%) of individuals within ≥4 age classes. Consequently, the sustained increase in fishing effort in recent years has not resulted in a reduction in the size of individual krill. The mean krill length showed a significant positive correlation with the depth (r = 0.36, p < 0.01) and temperature (r = 0.26, p < 0.01) of the krill cluster, and a significant negative correlation with resource density (r = −0.20, p < 0.01), year (ρ = −0.31, p < 0.01) and latitude (ρ = −0.31, p < 0.01). The length exhibited U-shaped temporal trends, and latitudinal and longitudinal nonlinearity. Body size was positively correlated with depth (p < 0.01), whereas as temperature increased, body size first increased and then remained constant. As density increased, the mean krill length increased first and then slowly decreased. Recent warming intensifies population shifts, with potential cascading effects on ecosystem structure and carbon sequestration. Full article

Background: Exercise-induced bronchoconstriction (EIB) is common in athletes, being more frequent in outdoor endurance-based/long-distance sports. We followed a World-Class marathon paddler’s season with recurrent episodes of EIB, which intensified during cold exposure workouts. This unique immunophenotype profile during the season and its variations were reflected in acute and chronic inflammatory markers. Methods: A longitudinal case study was conducted with blood sampling obtained from a single paddler after overnight fasting at three timepoints: T1 (beginning of season, after 15-day rest period), T2 (post-Winter National Championship), and T3 (post-Summer National Championship). Complete blood counts and lymphocyte immunophenotyping were performed using automated hematology analysis and multiparametric flow cytometry. Results: The total numbers of leukocytes (T1: 6.3; T2: 5.0; T3: 5.5 × 10⁹/L), neutrophils (3.1; 2.5; 2.8 × 10⁹/L), and lymphocytes (2.4; 1.8; 2.2 × 10⁹/L) declined between T1 and T2, followed by a partial recovery at T3. In contrast, monocyte counts exhibited the reverse pattern (0.41; 0.62; 0.31 × 10⁹/L). The two T cell subsets (αβ and γδ) remained relatively stable, showing only minor seasonal fluctuations. CD19+ B cells, initially at very low levels, increased steadily as the season progressed (0.05; 0.07; 0.16 × 10⁹/L). During T2, the proportion of memory lymphocytes (CD45RO+) rose, while naive cells (CD45RA+) declined; this trend was subsequently inverted at M3. Although the CD4+/CD8+ ratio varied over time, it consistently stayed below the normal reference range established for healthy controls (0.50; 0.83; 0.60 for T1, T2, and T3, respectively). Conclusions: The immune assessment of the World-Class marathon paddler revealed transient immunosuppression early in the season, marked by reduced neutrophils, a low CD4+/CD8+ ratio, and diminished CD19+ lymphocytes. Over time, immune parameters showed signs of recovery, indicating a temporary imbalance that did not impair the athlete’s physical performance. Conclusions: This case study of an elite marathon kayaker revealed transient immune fluctuations across a competitive season, including early immunosuppression (low neutrophils, CD4+/CD8+ ratio 0.50, and minimal CD19+ B cells) followed by partial recovery mid- and late-season. Despite persistently inverted CD4+/CD8+ ratios suggesting chronic immune dysregulation, the athlete maintained competitive performance, highlighting the temporary nature of these changes and emphasizing that regular immune monitoring can help optimize health and performance in elite athletes. Full article

Background/Objectives: Nitrosamine drug substance-related impurities (NDSRIs) are a class of potent genotoxic impurities that pose a critical risk to patient safety, thereby necessitating the stringent control of pharmaceutical products. Nortriptyline (NORT) and sertraline (SERT) are two widely prescribed antidepressants that form highly potent NDSRIs, N-nitroso-nortriptyline (NNORT) and N-nitroso-sertraline (NSERT), respectively. Despite these risks, a substantial gap exists in terms of the validated analytical methods for surveillance. Accordingly, this study addressed this need by developing a liquid chromatography–tandem mass spectrometry method for the quantification of NNORT and NSERT in drug products. Methods: A comparative evaluation of two reversed-phase columns (general-purpose C18 column and phenyl-hexyl column) was performed to achieve optimal chromatographic resolution of the parent active pharmaceutical ingredients (APIs). Results: The phenyl-hexyl column demonstrated superior separation for both NDSRI/API pairs by leveraging π-π interactions to markedly enhance the resolution. This was particularly critical for SERT. The method was fully validated according to the International Council for Harmonization guideline Q2(R1) and demonstrated excellent linearity (r² = 0.998 for both NNORT and NSERT) with limits of quantitation of 20 ng/g for NNORT and 125 ng/g for NSERT. Accuracy was confirmed with recoveries of 96.6–99.4% for NNORT and 98.6–99.4% for NSERT, and precision was acceptable, with relative standard deviation below 3.9% and 1.9%, respectively. The application of this method to commercial products subjected to accelerated stress testing revealed NNORT formation in NORT products with an average concentration of 190 ng/g, as well as NSERT formation in SERT products resulted in an average concentration of 172 ng/g. Conclusions: This validated method provides a reliable tool for routine quality control, thereby enabling pharmaceutical manufacturers and regulatory agencies to ensure safety and compliance with widely used antidepressant medications. Full article

Background: Pulmonary hypertension is common in left-sided heart valve disease, with historical studies reporting mortality rates up to 31% in severe cases undergoing mitral valve surgery. This study evaluates the impact of severe pulmonary hypertension on outcomes of mechanical mitral valve replacement with posterior leaflet preservation by comparing results with patients having mild-to-moderate pulmonary hypertension. Methods: Prospective analysis of 86 patients with mitral valve disease undergoing mechanical valve replacement with posterior leaflet preservation from March 2015 to September 2016 was conducted. Patients were stratified by pulmonary artery pressure: severe (≥60 mmHg, n = 19) versus mild–moderate (35–59 mmHg, n = 67). Primary outcomes included mortality, complications, and functional recovery at 1, 6, and 12 months. Results: The cohort included 67 patients (77.9%) with mild–moderate pulmonary hypertension and 19 patients (22.1%) with severe pulmonary hypertension. Severe pulmonary hypertension patients demonstrated higher NYHA functional class (73.7% class III vs. 46.2%, p = 0.03), larger left atrial diameter (56.3 ± 9.8 vs. 49.5 ± 6.7 mm, p = 0.01), and higher mean pressure gradients (14.4 ± 5.3 vs. 11.3 ± 5.0 mmHg, p = 0.025). Mortality was 5.3% in the severe group versus 0% in the mild–moderate group (p = 0.331). Patients with severe pulmonary hypertension required longer ICU stays (6.3 ± 3.7 vs. 4.7 ± 2.2 days, p = 0.024) but showed no significant differences in ventilation time, reoperation rates, or major complications. At the 12-month follow-up, both groups achieved equivalent outcomes in pulmonary artery pressures, left ventricular function, and cardiac dimensions. Conclusion: In this study with a relatively small sample size, severe pulmonary hypertension was associated with significantly longer intensive care unit stay but not with higher mortality compared to mild–moderate pulmonary hypertension, with both groups attaining comparable functional and hemodynamic parameters at 12 months after mechanical mitral valve replacement with posterior leaflet preservation. Full article

Shape-memory polymers (SMPs) are a unique class of smart materials capable of recovering their original shape upon external stimuli, with thermoresponsive polyurethane (PU) being one of the most widely studied systems. However, the relatively low mechanical strength, thermal stability, and durability of PU limit its broader functional applications. PU/ND composites containing 0.1–0.5 wt.% ND were fabricated via melt blending and injection molding method. The objective was to evaluate the effect of ND reinforcement on the mechanical, scratch, thermal, rheological, and shape-memory properties. Results show that tensile strength increased up to 114% and Young’s modulus by 11% at 0.5 wt.% ND, while elongation at break decreased due to restricted chain mobility. Hardness improved by 21%, and scratch resistance was significantly enhanced, with the coefficient of friction reduced by 56% at low loads. Thermal stability was improved, with the maximum degradation temperature shifting from 350 °C (pure PU) to 362 °C (0.5 wt.% PU/ND) and char yield increasing by 34%. DSC revealed an increase in glass transition temperature from 65 °C to 68.6 °C. Rheological analysis showed an 89% reduction in damping factor (tan δ), indicating enhanced elasticity. Shape-memory tests confirmed notable improvements in both shape fixity and recovery ratios across successive cycles compared to neat PU, with the highest enhancements observed for the 0.5 wt.% PU/ND nanocomposite—showing up to 7.6% higher fixity and 32% higher recovery than pure PU. These results demonstrate that ND reinforcement effectively strengthens PU while preserving and improving its shape-memory behavior, making the composites promising candidates for high-performance smart materials in sensors, actuators, and aerospace applications. Full article

Background: Studies assessing poor postoperative recovery using patient-centered metrics among older adults are scarce. We aimed to explore poor postoperative recovery in octogenarians and nonagenarians, characterized using the validated patient-centered tool ‘days alive and out of hospital’ (DAOH). Methods: This retrospective cohort study included patients aged ≥ 80 years who had non-palliative surgery at a tertiary academic center between January 2017 and July 2021. We explored the incidence of DAOH at 90 days (DAOH₉₀) ≤ 45 days as a pragmatic patient-centered marker of poor postoperative recovery. We also identified independent risk factors associated with this outcome using logistic regression models. Sensitivity analyses were performed using similar regression models. Results: Among 3683 included patients (median age 84 years), 640 patients (17%) had poor postoperative recovery. Of them, 240 patients (38%) survived the 90-day postoperative period but suffered a cumulative hospitalization period of over 45 days, and 400 patients (62%) died during the 90-day postoperative period. The most significant risk factors were ASA physical status classification (adjusted odds ratio (aOR) 3.52 [95% CI 2.55–4.87] for class 3E-5E compared to class 1–2), renal failure (aOR 3.49 [2.01–6.06] for GFR < 15 compared to GFR > 60 mL/min/1.73 m²), and high-risk surgery (aOR 1.85 [1.47–2.32]). Conclusions: We found a non-trivial rate of poor postoperative recovery in octogenarians and nonagenarians. DAOH₉₀ ≤ 45 days is a simple, clear, and intuitive tool that may enhance patient-centered research and promote communication about expected outcomes, support shared decision making, and provide personalized risk assessment aligned with older patients’ goals of care. Full article

Bio-gels are a class of functional polymeric materials with three-dimensional network structures. Their exceptional biocompatibility, biodegradability, high specific surface area, and tunable physicochemical properties make them highly promising for environmental remediation. This article systematically reviews the classification of bio-gels based on source, cross-linking mechanisms, and functional attributes. It also elaborates on their fundamental properties such as porous structure, high water absorbency, stimuli-responsiveness, and mechanical stability and examines how these properties influence their environmental remediation efficiency. This review comprehensively analyze the mechanisms and efficacy of bio-gels in adsorbing heavy metal ions, removing organic dyes, improving soil water retention, and restoring ecosystems. Special attention is given to the interactions between surface functional groups and contaminants, the role of porous structures in mass transfer, and the ecological effects within soil–plant systems. Additionally, this review explores extended applications of bio-gels in medical tissue engineering, controlled release of drugs and fertilizers, and enhanced oil recovery, highlighting their versatility as multifunctional materials. Finally, based on current progress and challenges, this review outline key future research directions. These include elucidating microscopic interaction mechanisms, developing low-cost renewable feedstocks, designing multi-stimuli-responsive structures, improving long-term stability, and establishing full life-cycle environmental safety assessments. These efforts will help advance the efficient, precise, and sustainable use of bio-gels in environmental remediation, offering innovative solutions to complex environmental problems. Full article

Ecological restoration of mine wastelands is central to biodiversity conservation and ecosystem recovery worldwide. However, the long-term ecological consequences of active restoration versus natural regeneration remain debated, particularly in mountainous karst landscapes. Using a space-for-time substitution, we established a five-stage chronosequence—recently abandoned, 10 years, 20 years, 30 years, and a late-successional forest (>35 years)—in a typical underground coal-mine wasteland in eastern Yunnan, southwest China. Each age class contained paired active restoration and natural regeneration sites; the late-successional forest served as a reference. We surveyed nested vegetation plots (20 × 20 m with shrub and herb subplots) in summer and autumn, recorded vertebrate species with camera traps, and quantified α-diversity (species richness, Shannon–Wiener diversity, Simpson’s diversity, Pielou’s evenness) and β-diversity (Bray–Curtis dissimilarity, non-metric multidimensional scaling). Overall plant α-diversity was highest in natural regeneration and lowest in active restoration, whereas tree-layer diversity was highest in active restoration and shrub and herb layers were richer under natural regeneration. Preliminary data from our camera traps suggested that animal species richness ranked late-successional forest > natural regeneration > active restoration, but evenness peaked in active restoration, suggesting early-stage homogenization. Plant β-diversity indicated stronger compositional divergence among active restoration sites and greater similarity between natural regeneration and the reference forest; both modes converged toward the reference forest over time but followed distinct patterns. These findings suggest that active restoration accelerates structural development yet increases between-site heterogeneity, whereas natural regeneration maintains higher overall diversity and compositional similarity to reference communities. Our results provide preliminary empirical guidance for selecting restoration strategies in similar karst coal-mine landscapes. Full article

To address the limitation that single-index evaluation fails to fully reflect the development performance of reservoirs of different types and at various development stages, a multi-index comprehensive evaluation system featuring the workflow of “index screening–weight determination–model evaluation–strategy guidance” was established. Firstly, the grey correlation analysis method (with a correlation degree threshold set at 0.65) was employed to screen 12 key evaluation indicators, including reservoir physical properties (porosity, permeability) and development dynamics (recovery factor, water cut, well activation rate). Subsequently, the fuzzy analytic hierarchy process (FAHP, for subjective weighting, with the consistency ratio (CR) of expert judgments < 0.1) was coupled with the attribute measurement method (for objective weighting, with information entropy redundancy < 5%) to determine the indicator weights, thereby balancing the influences of subjective experience and objective data. Finally, two evaluation models, namely the fuzzy comprehensive decision-making method and the unascertained measurement method, were constructed to conduct evaluations on 308 reservoirs in the Liaohe Oilfield (covering five major categories: integral medium–high-permeability reservoirs, complex fault-block reservoirs, low-permeability reservoirs, special lithology reservoirs, and thermal recovery heavy oil reservoirs). The results indicate that there are 147 high-efficiency reservoirs categorized as Class I and Class II in total. Although these reservoirs account for 47.7% of the total number, they control 71% of the geological reserves (154,548 × 10⁴ t) and 78% of the annual oil production (738.2 × 10⁴ t) in the oilfield, with an average well activation rate of 65.4% and an average recovery factor of 28.9. Significant quantitative differences are observed in the development characteristics of different reservoir types: Integral medium–high-permeability reservoirs achieve an average recovery factor of 37.6% and an average well activation rate of 74.1% by virtue of their excellent physical properties (permeability mostly > 100 mD), with Block Jin 16 (recovery factor: 56.9%, well activation rate: 86.1%) serving as a typical example. Complex fault-block reservoirs exhibit optimal performance at the stage of “recovery degree > 70%, water cut ≥ 90%”, where 65.6% of the blocks are classified as Class I, and the recovery factor of blocks with a “good” rating (42.3%) is 1.8 times that of blocks with a “poor” rating (23.5%). For low-permeability reservoirs, blocks with a rating below medium grade account for 68% of the geological reserves (8403.2 × 10⁴ t), with an average well activation rate of 64.9%. Specifically, Block Le 208 (permeability < 10 mD) has an annual oil production of only 0.83 × 10⁴ t. Special lithology reservoirs show polarized development performance, as Block Shugu 1 (recovery factor: 32.0%) and Biantai Buried Hill (recovery factor: 20.4%) exhibit significantly different development effects due to variations in fracture–vug development. Among thermal recovery heavy oil reservoirs, ultra-heavy oil reservoirs (e.g., Block Du 84 Guantao, with a recovery factor of 63.1% and a well activation rate of 92%) are developed efficiently via steam flooding, while extra-heavy oil reservoirs (e.g., Block Leng 42, with a recovery factor of 19.6% and a well activation rate of 30%) are constrained by reservoir heterogeneity. This system refines the quantitative classification boundaries for four development levels of water-flooded reservoirs (e.g., for Class I reservoirs in the high water cut stage, the recovery factor is ≥35% and the water cut is ≥90%), as well as the evaluation criteria for different stages (steam huff and puff, steam flooding) of thermal recovery heavy oil reservoirs. It realizes the transition from traditional single-index qualitative evaluation to multi-index quantitative evaluation, and the consistency between the evaluation results and the on-site development adjustment plans reaches 88%, which provides a scientific basis for formulating development strategies for the Liaohe Oilfield and other similar oilfields. Full article

The article presents the results of research and development work conducted as part of the H2GEO project, aimed at creating a comprehensive technology for the processing of post-mining coal waste heaps. The core of the solution is a mobile density separation system based on a pulsating jig, enabling effective recovery of carbonaceous and mineral fractions. Laboratory experiments assessed the impact of key process parameters—such as sieve slot size, pulsation frequency, and enrichment time—on the efficiency and accuracy of separation for different grain size classes. The most favorable results were obtained using a 2.5 mm screen, a pulsation frequency of 60 min⁻¹, and extended enrichment time, which ensured high-quality separation and low ash content in the carbon-bearing product. The findings supported the design of a new industrial separator (jig) equipped with advanced control systems, facilitating the production of homogeneous fractions suitable for further processing into hydrogen, geopolymers, and construction materials. The proposed solution aligns with circular economy principles, promoting waste reuse, environmental hazard mitigation, and the revitalization of degraded post-industrial areas. Full article

In this article, function-theoretic and probabilistic approaches to the recovery of functions from Korobov classes in Lebesgue metrics are considered. Exact order estimates are obtained for the recovery errors of functions reconstructed from both accurate and inaccurate information given by the trigonometric Fourier–Lebesgue coefficients of the recovered function in the uniform metric. Within these settings, optimal computational aggregates (optimal recovery methods) are constructed. The boundary of inaccurate information (the limiting error ${\tilde{\epsilon }}_N$) that preserves the order of recovery corresponding to accurate information is identified. Furthermore, a set of computational aggregates is constructed whose limiting errors do not exceed ${\tilde{\epsilon }}_N$. A procedure for constructing a probability measure on functional classes is presented, and upper bounds for the mean-square recovery error with respect to these measures on Korobov classes are established. Numerical experiments were conducted to validate the theoretical results. These experiments showed that for the function corresponding to the lower bound in Theorem 1 (cases C(N)D-2 and C(N)D-3), the ratio between the function value and the approximation error remains constant in the case of uniform weighting and increases indefinitely when logarithmic weighting is used as the number of terms N grows. Full article

Anti-tank landmines endanger post-conflict recovery. Detecting camouflaged TM-62 landmines in low-altitude unmanned aerial vehicle (UAV) imagery is challenging because targets occupy few pixels and are low-contrast and often occluded. We introduce a single-class anti-tank dataset and a YOLOv5 pipeline augmented with a SAHI-based small-object stage and Weighted Boxes Fusion. The evaluation combines COCO metrics with an operational operating point (score = 0.25; IoU = 0.50) and stratifies by object size and occlusion. On a held-out test partition representative of UAV acquisition, the baseline YOLOv5 attains mAP@0.50:0.95 = 0.553 and AP@0.50 = 0.851. With tuned SAHI (768 px tiles, 40% overlap) plus fusion, performance rises to mAP@0.50:0.95 = 0.685 and AP@0.50 = 0.935—ΔmAP = +0.132 (+23.9% rel.) and ΔAP@0.50 = +0.084 (+9.9% rel.). At the operating point, precision = 0.94 and recall = 0.89 (F1 = 0.914), implying a 58.4% reduction in missed detections versus a non-optimized SAHI baseline and a +14.3 AP@0.50 gain on the small/occluded subset. Ablations attribute gains to tile size, overlap, and fusion, which boost recall on low-pixel, occluded landmines without inflating false positives. The pipeline sustains real-time UAV throughput and supports actionable triage for humanitarian demining, as well as motivating RGB–thermal fusion and cross-season/-domain adaptation. Full article

The growing implementation of close-to-nature forestry practices in the management of northern forests, characterized by dispersed harvesting operations, has heightened the importance of minimizing damage to residual stands as a key aspect of sustainable forest management. The objective of this study is to examine and compare the resistance of various tree species and diameter classes to wounds incurred during logging operations of differing sizes, intensities, and locations. In addition, the research aims to assess temporal changes in wound characteristics, including healing and closure processes, across species. This long-term, 18-year investigation was conducted in the Kheyrud Forest, located within the Hyrcanian broadleaf forest region of northern Iran, to evaluate the dynamics of wound healing in residual trees following ground-based skidding operations. Through a comprehensive assessment of 272 wounded trees across six species, we demonstrate that species significantly influences healing ratio (Kruskal–Wallis, p < 0.01), with Oriental beech (Fagus orientalis Lipsky) (50.6%) showing superior recovery compared to the Chestnut-leaved oak (Quercus castaneifolia) (37.5%). Healing ratio decreased with larger diameter at breast height (DBH) (R² = 0.114, p < 0.01), while absolute healed area increased. Larger areas (>1000 cm²) reduced healing by 42.3% versus small wounds (<500 cm²) (R² = 0.417, p < 0.01). Severe wounds (deep gouges) showed 19% less healing than superficial injuries (p = 0.003). Circular wounds healed significantly better than rectangular forms (χ² = 24.92, p < 0.001). Healing ratio accelerated after the first decade, reaching 69% by year 17 (R² = 0.469, p < 0.01). Wound height (p = 0.117) and traffic intensity (p = 0.65) showed no statistical impact. Contrary to expectations, stem position had no significant effect on wound recovery, whereas wound geometry proved to be a critical determinant. The findings highlight that appropriate species selection, minimizing wound size (to less than 500 cm²), and adopting extended cutting cycles (exceeding 15 years) are essential for enhancing residual stand recovery in close-to-nature forestry systems. Full article

University campus teaching areas are essential spaces for students’ daily learning and recovery, in which soundscapes play a crucial role in shaping restorative experiences. This study aimed to explore the restorative effects of soundscapes in campus teaching areas and the factors influencing these effects. Field surveys, psychological assessments, and physiological experiments were conducted to evaluate restorative perceptions, which were characterized by three dimensions: Attractiveness, Coherence, and Being Away. The findings indicate that both the visual environment and acoustic characteristics significantly shaped restorative outcomes. Natural landscapes, particularly green areas and waterscapes, enhanced the restorative potential of soundscapes, while natural sounds, such as birdsong, fountain sound, and rustling leaves, were perceived as more restorative. In contrast, traffic noise, crowd noise, and class bell sound reduced restorative perceptions. Furthermore, the signal-to-noise ratio (SNR) played a critical role, with the higher SNR values of birdsong relative to traffic noise being associated with stronger restorative effects. These results suggest that campus soundscape design should prioritize green landscapes, introduce or amplify natural sounds, and optimize the SNR of restorative sounds. Overall, this research provides both theoretical support and practical guidance for designing healthier campus environments that foster students’ recovery and well-being. Full article

Background/Objectives: Pediatric postoperative pulmonary complication is a major event associated with increased in-hospital morbidity and mortality. However, data is limited regarding the specific timing and spectrum of postoperative pulmonary complications in the pediatric population. Utilizing data in a cohort of high-risk patients aged ≤ 6 years, we sought to evaluate the timing and incidence of a composite of postoperative pulmonary complications. We hypothesized that ASA physical status, emergent case type, and procedure duration would be associated with pulmonary complications in high-risk children and that these complications would, in turn, be associated with a prolonged length of stay. Methods: Data from patients ≤ 6 years of age who were intubated for major abdominal surgery at the authors’ institution were collected from 1 January 2019 to 28 March 2022. The primary outcome was postoperative pulmonary complication, defined as the occurrence/use of reintubation, non-invasive positive pressure ventilation, high-flow nasal cannula, mask, or nasal cannula beyond phase 1 of recovery after anesthesia and within 7 postoperative days. The secondary outcome was hospital length of stay. We performed multivariable logistic regression with backward selection to identify independent predictors for postoperative pulmonary complications after adjusting for covariates. For hospital length of stay, a multivariate linear regression model was used after adjusting for covariates. Results: A total of 88 (26.1%) patients experienced 117 occurrences of postoperative oxygen dependence events, and 80 (90.9%) experienced this event in the first 48 h after surgery. The results of this model demonstrated independent associations between patients with an ASA class of IV (OR 9.86, 95% CI: 1.22–79, p-value = 0.03202) and longer operative time (OR: 1.05, 95% CI: 1.03–1.08, p = 0.00001) and postoperative pulmonary complication. On adjusted analysis, the occurrence of a postoperative pulmonary complication was associated with prolonged postoperative length of stay (adjusted geometric mean ratio of 1.39 (95% CI 1.10–1.75, p = 0.0062). Conclusions: Pediatric postoperative pulmonary complication remains a significant event for many patients and results in a prolonged length of stay. This study lays the groundwork for further investigations of interventions targeted at optimizing and monitoring at-risk individuals. Full article