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BACKGROUND: Post-lung transplantation (LTx) fluid accumulation can lead to dilution of serum creatinine (SCr). We hypothesized that fluid accumulation might impact the diagnosis, staging, and outcome of posttransplant acute kidney injury (AKI). METHODS: In this retrospective study, we analyzed data from 131 adult LTx patients at a single German lung center between 2005 and 2018. We assessed the occurrence of AKI within 7 days posttransplant, both before and after SCr-adjustment for fluid balance (FB), and investigated its impact on all-cause mortality. Transient and persistent AKIs were defined as return to baseline kidney function or continuation of AKI beyond 72 h of onset, respectively. RESULTS: AKI was diagnosed in 58.8% of patients according to crude SCr values. When considering FB-adjusted SCr values, AKI severity was underestimated in 20.6% of patients, that is, AKI was detected in an additional 6.9% of patients and led to AKI upstaging in 23.4% of cases. Patients initially underestimated but detected with AKI only after FB adjustment had higher mortality compared to those who did not meet AKI criteria (hazard ratio [HR] 2.98; 95% confidence interval [CI] 1.06, 8.36; p = 0.038). Persistent AKI was associated with higher mortality than transient AKI, regardless of using crude or adjusted SCr values (p < 0.05). Persistent AKI emerged as an independent risk factor for mortality (HR 2.35; 95% CI 1.29, 4.30; p = 0.005). CONCLUSION: Adjusting for FB and evaluating renal recovery patterns post-AKI may enhance the sensitivity of AKI detection. This approach could help identify patients with poor prognosis and potentially improve outcomes in lung transplant recipients. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT03039959, NCT03046277.
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Injúria Renal Aguda , Transplante de Pulmão , Complicações Pós-Operatórias , Humanos , Masculino , Feminino , Transplante de Pulmão/efeitos adversos , Estudos Retrospectivos , Injúria Renal Aguda/etiologia , Injúria Renal Aguda/diagnóstico , Pessoa de Meia-Idade , Prognóstico , Complicações Pós-Operatórias/diagnóstico , Seguimentos , Fatores de Risco , Taxa de Sobrevida , Taxa de Filtração Glomerular , Adulto , Transplantados , Índice de Gravidade de Doença , Sobrevivência de Enxerto , Creatinina/sangueRESUMO
Background: Nucleated red blood cells (nRBC) are precursor cells of the erythropoiesis that are absent from the peripheral blood under physiological conditions. Their presence is associated with adverse outcomes in critically ill patients. This study aimed to evaluate the predictive value of nRBC on mortality in intensive care unit (ICU) patients with COVID-19 acute respiratory distress syndrome (ARDS). Material and methods: This retrospective, observational cohort study analyzed data on 206 ICU patients diagnosed with COVID-19 ARDS between March 2020 and March 2022. The primary endpoint was ICU mortality, and secondary endpoints included ICU and hospital stay lengths, ventilation hours, and the time courses of disease severity scores and clinical and laboratory parameters. Results: Among the included patients, 68.9% tested positive for nRBC at least once during their ICU stay. A maximum nRBC of 105 µl-1 had the highest accuracy in predicting ICU mortality (area under the curve of the receiver operating characteristic [AUCROC] 0.780, p < 0.001, sensitivity 69.0%, specificity 75.5%). Mortality was significantly higher among patients with nRBC >105 µl-1 than ≤105 µl-1 (86.5% vs. 51.3%, p = 0.008). Compared to patients negative for nRBC in their peripheral blood, those positive for nRBC required longer mechanical ventilation (127 [44 - 289] h vs. 517 [255 - 950] h, p < 0.001), ICU stays (12 [8 - 19] vs. 27 [13 - 51] d, p < 0.001), and hospital stays (19 [12 - 29] d vs. 31 [16 - 58] d, p < 0.001). Peak Sepsis-related Organ Failure Assessment (SOFA), Simplified Acute Physiology Score, PaO2/FiO2, interleukin-6, and procalcitonin values were reached before the peak nRBC level. However, the predictive performance of the SOFA (AUCROC 0.842, p < 0.001) was considerably improved when a maximum SOFA score >8 and nRBC >105 µl-1 were combined. Discussion: nRBC predict ICU mortality and indicate disease severity among patients with COVID-19 ARDS, and they should be considered a clinical alarm signal for a worse outcome. nRBC are a late predictor of ICU mortality compared to other established clinical scoring systems and laboratory parameters but improve the prediction accuracy when combined with the SOFA score.
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COVID-19 , Síndrome do Desconforto Respiratório , Sepse , Humanos , Estudos Retrospectivos , Unidades de Terapia Intensiva , Estudos de Coortes , Biomarcadores , EritrócitosRESUMO
Ultrasonic Testing (UT) has seen increasing application of machine learning (ML) in recent years, promoting higher-level automation and decision-making in flaw detection and classification. Building a generalized training dataset to apply ML in non-destructive evaluation (NDE), and thus UT, is exceptionally difficult since data on pristine and representative flawed specimens are needed. Yet, in most UT test cases flawed specimen data is inherently rare making data coverage the leading problem when applying ML. Common data augmentation (DA) strategies offer limited solutions as they don't increase the dataset variance, which can lead to overfitting of the training data. The virtual defect method and the recent application of generative adversarial neural networks (GANs) in UT are sophisticated DA methods targeting to solve this problem. On the other hand, well-established research in modeling ultrasonic wave propagations allows for the generation of synthetic UT training data. In this context, we present a first thematic review to summarize the progress of the last decades on synthetic and augmented UT training data in NDE. Additionally, an overview of methods for synthetic UT data generation and augmentation is presented. Among numerical methods such as finite element, finite difference, and elastodynamic finite integration methods, semi-analytical methods such as general point source synthesis, superposition of Gaussian beams, and the pencil method as well as other UT modeling software are presented and discussed. Likewise, existing DA methods for one- and multidimensional UT data, feature space augmentation, and GANs for augmentation are presented and discussed. The paper closes with an in-detail discussion of the advantages and limitations of existing methods for both synthetic UT training data generation and DA of UT data to aid the decision-making of the reader for the application to specific test cases.
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Based on the fact that cogwheels are indispensable parts in manufacturing, we present the acoustic resonance testing (ART) of small data on sintered cogwheels for quality control in the context of non-destructive testing (NDT). Considering the lack of extensive studies on cogwheel data by means of ART in combination with machine learning (ML), we utilize time-frequency domain feature analysis and apply ML algorithms to the obtained feature sets in order to detect damaged samples in two ways: one-class and binary classification. In each case, despite small data, our approach delivers robust performance: All damaged test samples reflecting real-world scenarios are recognized in two one-class classifiers (also called detectors), and one intact test sample is misclassified in binary ones. This shows the usefulness of ML and time-frequency domain feature analysis in ART on a sintered cogwheel dataset.
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Algoritmos , Aprendizado de Máquina , AcústicaRESUMO
BACKGROUND: COVID-19 can induce acute respiratory distress syndrome (ARDS). In patients with congenital heart disease, established treatment strategies are often limited due to their unique cardiovascular anatomy and passive pulmonary perfusion. CASE PRESENTATION: We report the first case of an adult with single-ventricle physiology and bidirectional cavopulmonary shunt who suffered from severe COVID-19 ARDS. Treatment strategies were successfully adopted, and pulmonary vascular resistance was reduced, both medically and through prone positioning, leading to a favorable outcome. CONCLUSION: ARDS treatment strategies including ventilatory settings, prone positioning therapy and cannulation techniques for extracorporeal oxygenation must be adopted carefully considering the passive venous return in patients with single-ventricle physiology.
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COVID-19/diagnóstico por imagem , Cardiomegalia/diagnóstico por imagem , Procedimentos Cirúrgicos Cardiovasculares/métodos , Dextrocardia/diagnóstico por imagem , Oxigenação por Membrana Extracorpórea/métodos , Doenças Genéticas Ligadas ao Cromossomo X/diagnóstico por imagem , Síndrome de Heterotaxia/diagnóstico por imagem , Posicionamento do Paciente/métodos , COVID-19/complicações , COVID-19/terapia , Cardiomegalia/complicações , Cardiomegalia/terapia , Dextrocardia/complicações , Dextrocardia/terapia , Doenças Genéticas Ligadas ao Cromossomo X/complicações , Doenças Genéticas Ligadas ao Cromossomo X/terapia , Síndrome de Heterotaxia/complicações , Síndrome de Heterotaxia/terapia , Humanos , Masculino , Pessoa de Meia-Idade , Índice de Gravidade de DoençaRESUMO
INTRODUCTION: Treatment of high-risk pulmonary embolism (PE) in perioperative patients remains challenging. Systemic thrombolysis is associated with a high risk of major bleedings and intracranial haemorrhage. High mortality rates are reported for open pulmonary embolectomy. Therefore, postoperative surgical patients may benefit substantially from catheter-directed ultrasound-accelerated thrombolysis (USAT). CASE PRESENTATION: We report two cases of high-risk perioperative PE. Both patients developed severe haemodynamic instability leading to cardiac arrest. After the implantation of a veno-arterial extracorporeal membrane oxygenation (ECMO), they were both successfully treated with USAT. Adequate improvement of right ventricular function was achieved; thus, ECMO could be successfully weaned after 3 and 4 days, respectively. Both patients showed favourable outcomes and could be discharged to rehabilitation. CONCLUSION: Current guidelines on treatment of PE offer no specific therapies for perioperative patients with high-risk PE. However, systemic thrombolysis is often excluded due to the perioperative setting and the risk of major bleeding. Catheter-directed thrombolysis was shown to utilise less thrombolytic agent while obtaining comparable thrombolytic effects. The risk for major bleeding (including intracranial haemorrhage) is also significantly lowered. Until further trials determining the value of adopted treatment strategies of high-risk PE in perioperative patients are available, USAT should be considered in similar cases.
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We investigated the main drivers of eggs and larvae distributions of European sardine and anchovy from the NW Mediterranean Sea. We used Generalized Additive Models and satellite environmental data. Mainly sea surface temperature, but also currents, surface height, and primary production were significantly correlated with both species' early stages distributions. Anchovy optimal temperature upper limit was not detected, but sardine eggs and larvae presented a small-ranged bell-shape curve relationship to SST with an upper SST threshold around 13 °C. Sardine spawning during winter appeared to be dependant not only on in-situ environmental conditions but also on summer conditions prior to the spawning event. Model predictions of the larval and spawning habitat distribution showed clear differences between developmental stages and between species, confirming a worsening of the sardine habitat with time. Considering the further increase of surface temperature predicted in the years to come, the survival of the sardine in the region could be compromised.
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Ecossistema , Peixes , Animais , Larva , Mar Mediterrâneo , Alimentos MarinhosRESUMO
The early administration of fibrinogen has gained wide acceptance for the treatment of major hemorrhage, whereas the substitution of coagulation factor XIII (FXIII) is only supported by a low level of evidence. This study aimed to answer the question of whether a combined therapy of fibrinogen/FXIII substitution performs superiorly to sole fibrinogen administration in the treatment of dilutional coagulopathy. An in-vitro model of massive transfusion was used to compare the effect of combined fibrinogen/FXIII administration to that of sole fibrinogen therapy for the treatment of dilutional coagulopathy. For this purpose, the blood of red blood cell concentrates, fresh frozen plasma, and platelet concentrates were reconstituted in a ratio of 4:4:1, and then diluted with gelatin by 20% and 40%, respectively. Clot formation and stability were analyzed by thrombelastography. Both sole fibrinogen therapy (equivalent to 50 mg/kg) and the combined administration of fibrinogen (equivalent to 50 mg/kg) and FXIII (equivalent to 75 International Units (IU)/kg) increased fibrinogen-dependent mean clot firmness independently of the degree of dilution (20% dilution: 7 (6.3-7.8) mm; 20% dilution fibrinogen: 13.5 (13-17.3) mm; 20% dilution fibrinogen/FXIII: 16.5 (15.3-18.8) mm; 40% dilution: 3 (2-3.8) mm; 40% dilution fibrinogen: 8 (7-11.3) mm; 40% dilution fibrinogen/FXIII: 10 (8.3-11.8) mm; all p < 0.01). However, no differences were identified between the two treatment arms. Compared to fibrinogen therapy, no beneficial effect of the combined administration of fibrinogen and FXIII for the treatment of dilutional coagulopathy was detected in this in-vitro massive transfusion model. The result was independent of the degree of dilution.
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INTRODUCTION: The management of periprosthetic joint infection (PJI) of the hip is a challenging procedure. One-stage exchange is carried out in specialist centres with comparable infection free survival rates. However, there is a paucity of long-term results of this approach in young patients. METHODS: All patients undergoing one-stage exchange due to PJI with a known causative organism ⩽45 years of age with a minimum of 10-year follow-up (mean 15 years; range 10-24 years) were enrolled in this retrospective study. Patients older than 45 years of age or patients with a two-stage procedure were excluded from the study. The primary outcome measure was failure rate with special focus on reinfection at latest follow-up. Failure was defined as revision surgery for infection. Furthermore, functional outcome using the Harris Hip Score was determined initially and at latest follow-up. 26 patients fulfilled the inclusion criteria and were available for final follow-up. RESULTS: The study cohort consists of 16 male and 10 female patients with a mean age of 36.8 years (range 20-45 years) and a mean BMI of 29.8 kg/m2 (range 20.7-40.6 kg/m2). Prior to the single-stage procedure, the patients underwent an average of 3.1 previous surgical interventions (range 1-9). The mean hospital stay after septic revision was 19.7 days (11-33 days). Most infections were caused by Staphylococcus epidermidis (n = 8, 30.8%), followed by Staph. aureus (n = 7, 26.9%) and Propionibacterium acnes (n = 6, 23.1%). At latest follow-up, the overall survival rate was 76.9 %, while infection control could be achieved in 96.2%. At final examination, the mean Harris Hip Score improved from 46.2 to 78.9 (range 18.0-99; SD, 22.6). CONCLUSIONS: Single-stage revision surgery for the management of PJI in patients ⩽45 years is a successful treatment option with high infection control, even after long-term follow-up.
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Artroplastia de Quadril , Infecções Relacionadas à Prótese , Adolescente , Adulto , Antibacterianos/uso terapêutico , Artroplastia de Quadril/efeitos adversos , Criança , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Infecções Relacionadas à Prótese/diagnóstico , Infecções Relacionadas à Prótese/epidemiologia , Infecções Relacionadas à Prótese/cirurgia , Reoperação , Estudos Retrospectivos , Resultado do Tratamento , Adulto JovemRESUMO
PURPOSE: To analyze the first results of calcium-phosphate-coated porous tibia cones. METHODS: Patients treated with TrabecuLink®-CaP Cones were retrospectively recruited from January 2016 to December 2017. These custom-made cones were produced using titanium alloy Ti-6Al-4 V (Tilastan®) and using additive manufacturing with a special calcium-phosphate coating (HX®-coating). Clinical outcome was evaluated using Oxford Knee Score. For radiological evaluation of the implants, patients sent us outpatient taken radiographs. A minimum follow-up of one year was required. Lastly, we analyzed postoperative complications and revision rates. RESULTS: 52 patients with revision knee arthroplasty (RKA) were recruited for final analysis, of whom, we had 17 septic RKAs (33%) and 35 aseptic cases of RKA (67%). The bone defects were grouped into 17 AORI Type 2A (32.7%), 14 Type 2B (26.9%) and 21 Type 3 (40.4%). After a mean follow-up of 22 months (13.2-34.8; SD = ± 10), we had 4 surgical revisions (7.7%), 2 septic and 2 aseptic cases. The mean Oxford Knee Score was 28.6 points (8-47; SD = ± 10). 22 of 28 radiographs (78.6%) showed regular positioning of the cones and TKAs at a mean follow-up of 16.8 months (13.2-34.8; SD = ± 6). Three patients (10.7%) showed slight radiolucencies in the bone-cement interfaces and 3 patients (10.7%) had beginning heterotopic ossifications. CONCLUSIONS: This study shows the initial clinical results of calcium-phosphate-coated tibia cones showing a good functional outcome. Further research should focus on long-term clinical and radiological follow-up.
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Artroplastia do Joelho , Materiais Revestidos Biocompatíveis/uso terapêutico , Prótese do Joelho , Reoperação , Tíbia/cirurgia , Fosfatos de Cálcio , Humanos , Desenho de Prótese , Estudos Retrospectivos , Resultado do TratamentoRESUMO
INTRODUCTION: Soft tissue swelling of the knee joint can be caused by many diseases. Lipomas are one of the most reasonable differential diagnoses we have to consider. Therefore, we now present the uncommon case of a Lipoma arborescens (LA) and differentiate it from a quite similar manifesting spindle cell lipoma as follows. CASE REPORT: A 49-years old patient reports about progressive knee pain for four years and observes an increasing joint swelling. This swelling is a soft tissue, shiftable tumour, not painful. The magnetic resonance imaging (MRI) with contrast agent brings the diagnosis of an advanced osteoarthritis of the knee joint and classifies the tumour as LA. Subsequently, we treat the osteoarthritis by implanting a total knee arthroplasty with simultaneous intraoperative tumour resection performed as total synovectomy. The histopathological processing confirms the clinically and radiologically made diagnosis of LA. SUMMARY: Lipoma arborescens presents an uncommon subgroup of Lipomas, which is characterized by a slowly progressive increasing soft tissue swelling, especially around bigger human joints. Due to its intraarticular location, the LA might become clinically relevant when it reaches a certain tumour size. Looking at the diagnostics, sonography, MRI and especially the histopathological processing give the crucial results. Final proof can only be made by histopathological examination. Additionally, we have some differential diagnoses to exclude. Under these we predominantly find the spindle cell lipoma, synovial haemagioma, vascular synovial malformations and tenosynovial giant-cell tumour. Furthermore, an atypical lipomatous tumour should be excluded by FISH-analysis via determining the MDM2-Genamplification.
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Artropatias , Lipoma , Humanos , Artropatias/diagnóstico por imagem , Artropatias/cirurgia , Articulação do Joelho/diagnóstico por imagem , Articulação do Joelho/cirurgia , Lipoma/diagnóstico por imagem , Lipoma/cirurgia , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , SinovectomiaRESUMO
Introduction: Information on the number of flatfish species and their depth distributions is scarce for the Eastern Tropical Pacific. Historical data is important to evaluate changes in ecosystems due to local, regional and global stressors. Objective: To provide information on the presence, depth distributions and lengths of flatfish species collected by trawl nets. Methods: Fish studies were conducted by trawling at four sites along the Pacific coast of Costa Rica by the survey vessels Skimmer (1979-1980), Nishin Maru (1987-1988) and Victor Hensen (1993-1994). The published lists of species were consulted, museum specimens were accessed, and an updated list of flatfish species assembled. Results: A total of 36 species were found over a depth range of 8-359 m. The family Paralichthyidae included 13 species followed by the Cynoglossidae with 12 species, Achiridae with six and Bothidae with five. Thirty-five species were collected at depths from 10-235 m in the Gulf of Nicoya and Golfo Dulce. Monolene asadeae was collected offshore at a depth range of 254-359 m. The Gulf of Nicoya estuary yielded 27 species during the Skimmer expedition over a depth range of 8-60 m, while 31 species were found during the V. Hensen survey at depths from 10-228 m. The V. Hensen survey in Golfo Dulce (20-235 m) collected 19 species, and 17 species in Coronado Bay (21-187 m). Off the Nicoya Peninsula (56-359 m) 13 species were collected by the Nishin Maru shrimp trawler. A total of 21 species (58 %) were found at depths greater than 100 m which were probably exposed to low oxygen concentrations. During the V. Hensen survey Symphurus chabanaudi and S. elongatus were collected more frequently in the Gulf of Nicoya, while S. leei was collected more frequently in Golfo Dulce. Cluster analyses based on presence-absence data for the Gulf of Nicoya and Golfo Dulce revealed low station similarity indicating possible habitat partitioning among species. The size (Total length) of 33 species measured from both the Gulf of Nicoya and Golfo Dulce ranged from 8 cm (Syacium cf longidorsale, Trinectes xanthurus) to 50 cm (S. ovale). Only 12 species were found with lengths over 20 cm. Data on flatfish landings by the semi-industrial fishing fleet for the period 2000-2016 indicates that this group represents less than 1 % of the total landings (shrimp and bycatch), with a minimum of 365 kg in 2001 and a maximum of 13 414 kg in 2013. Conclusions: The number of flatfish species of the Pacific coast of Costa Rica appears relatively high but comparable to the numbers found in other tropical regions. A reduced fishing impact on the populations together with this updated list of flatfish provide a good baseline for a new survey of fish populations. Both are important for a future updating of the trophic models available the Gulf of Nicoya and Golfo and their use as tools for better management of the ecosystems.
Introducción: Es escasa la información sobre el número de especies y la distribución batimétrica de los lenguados del Pacífico Este Tropical. Esos datos son importantes para evaluar cambios en los ecosistemas debidos a tensores locales, regionales y globales. Objetivo: Proveer información de la presencia, distribución batimétrica y longitudes de especies de lenguados recolectados por red de arrastre. Métodos: Evaluaciones de los peces mediante redes de arrastre fueron conducidas en cuatro sitios a lo largo de la costa del Pacífico de Costa Rica por los buques de investigación Skimmer (1979-1980), Nishin Maru (1987-1988) y Victor Hensen (1993-1994).Se consultó las listas publicadas de especies, se revisó ejemplares depositados en el museo y se integró una lista actualizada de especies de lenguados. Resultados: Un total de 36 especies de lenguados fueron encontrados en un ámbito de profundidad de 8 a 359 m. La familia Paralichthyidae incluyó 13 especies seguida por los Cynoglossidae con 12 especies, Achiridae tuvo seis y Bothidae cinco especies. Treinta y cinco especies fueron recolectadas entre 10 y 235 m en el Golfo de Nicoya y Golfo Dulce. Monolene asadeae fue recolectada aguas afuera en un ámbito de profundidad de 254-359 m. El Golfo de Nicoya produjo 27 especies durante la expedición del Skimmer y en un ámbito de profundidad de 8 a 60 m, mientras que 31 especies fueron encontradas durante el muestreo del V. Hensen en profundidades entre los 10 y 228 m. El muestreo del V. Hensen en el Golfo Dulce (20 a 235 m) produjo 19 especies y 17 en Bahía de Coronado (21-187 m). Afuera de la península de Nicoya (56-359 m) 13 especies fueron recolectadas por el camaronero Nishin Maru. Un total de 21 especies (58 %) fueron encontradas a profundidades mayores de 100 m y posiblemente expuestas a las bajas concentraciones de oxígeno. Durante el muestreo del V. Hensen, Symphurus chabanaudi y S. elongatus fueron capturados más frecuentemente en el Golfo de Nicoya, mientras S. leei lo fue en Golfo Dulce. El tamaño (Longitud Total) de 33 especies medidas en ambos Golfo de Nicoya y Golfo Dulce oscilaron entre 8 cm (Syacium cf longidorsale, Trinectes xanthurus) y 50 cm (S. ovale). Solo 12 especies fueron encontradas con longitudes mayores de 20 cm. Datos de desembarcos de lenguados por la flota semi-industrial para el periodo 2000-2016 indican que este grupo representa menos del 1 % de los desembarcos totales (camarones y fauna acompañante), con un mínimo de 365 kg en 2001 y un máximo de 13 414 kg en 2013. Conclusiones: Los análisis de conglomerados basados en datos de presencia-ausencia para el Golfo de Nicoya y Golfo Dulce revelaron baja similitud de estaciones indicando partición del hábitat entre las especies. La diversidad de la fauna de lenguados de la costa del Pacífico de Costa Rica aparece relativamente alta pero comparable con la encontrada en otras regiones tropicales. El número de buques arrastreros ha disminuido significativamente en el Pacífico de Costa Rica después del 2014. Esta reducción del impacto en las poblaciones y la lista actualizada de lenguados proveen una buena base para un nuevo estudio de las poblaciones de peces. Ambas son importantes para una futura actualización de los modelos tróficos disponibles para el Golfo de Nicoya y Golfo Dulce y su utilidad como herramientas para un mejor manejo de los ecosistemas.
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Animais , Linguado/classificação , Indústria Pesqueira , Fauna Bentônica , Costa RicaRESUMO
Stochastic feed-in of fluctuating renewable energies is steadily increasing in modern electricity grids, and this becomes an important risk factor for maintaining power grid stability. Here, we study the impact of wind power feed-in on the short-term frequency fluctuations in power grids based on an Institute of Electrical and Electronics Engineers test grid structure, the swing equation for the dynamics of voltage phase angles, and a series of measured wind speed data. External control measures are accounted for by adjusting the grid state to the average power feed-in on a time scale of 1 min. The wind power is injected at a single node by replacing one of the conventional generator nodes in the test grid by a wind farm. We determine histograms of local frequencies for a large number of 1-min wind speed sequences taken from the measured data and for different injection nodes. These histograms exhibit a common type of shape, which can be described by a Gaussian distribution for small frequencies and a nearly exponentially decaying tail part. Non-Gaussian features become particularly pronounced for wind power injection at locations, which are weakly connected to the main grid structure. This effect is only present when taking into account the heterogeneities in transmission line and node properties of the grid, while it disappears upon homogenizing of these features. The standard deviation of the frequency fluctuations increases linearly with the average injected wind power.
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Power flow dynamics in electricity grids can be described by equations resembling a Kuramoto model of non-linearly coupled oscillators with inertia. The coupling of the oscillators or nodes in a power grid generally exhibits pronounced heterogeneities due to varying features of transmission lines, generators, and loads. In studies aiming at uncovering mechanisms related to failures or malfunction of power systems, these grid heterogeneities are often neglected. However, over-simplification can lead to different results away from reality. We investigate the influence of heterogeneities in power grids on stable grid functioning and show their impact on estimating grid stability. Our conclusions are drawn by comparing the stability of an Institute of Electrical and Electronics Engineers test grid with a homogenized version of this grid.
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INTRODUCTION: Mechanical failure due to dislocation, fracture and acetabular wear is a major complication associated with the use of spacers in the management of periprosthetic joint infection (PJI). We have developed a novel custom-made spacer in the setting of two-stage septic revision hip arthroplasty and present the preliminary results of our technique. MATERIALS AND METHODS: Between May 2015 and November 2017, 30 patients underwent hip revision using the ENDO spacer technique in the setting of a two-stage septic exchange arthroplasty. The technique involves the dual mobility liner and the downsized stainless cemented straight stem in combination with antibiotic-loaded PMMA bone cement. The primary outcome measure was the overall spacer complication rate, particularly spacer dislocation. Furthermore, functional outcome using the Harris Hip Score (HHS) before spacer implantation and prior re-implantation was evaluated. RESULTS: The mean age of the patients was 69.8 years (range from 45 to 85; SD = 9.9 years). No microorganisms were preoperatively found in 23 (76.7%) cases. Successful re-implantation was performed in all patients after a mean spacer duration time of 53.6 days (range 14-288 days; SD = 48.2). Spacer-related complications occurred in only two patients (6.7%). The HHS significantly improved from 34.0 (range 3-62; SD = 15.1) to 48.1 (range 11-73; SD = 15.7) (p = 0.0008). CONCLUSIONS: The ENDO spacer surgical technique is a feasible option in the treatment of periprosthetic joint infection (PJI), with a low dislocation rate. Furthermore, it allows early mobilization with the possibility of full-weight bearing.
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Artrite Infecciosa/cirurgia , Artroplastia de Quadril/métodos , Infecções Relacionadas à Prótese/cirurgia , Reoperação/métodos , Idoso , Idoso de 80 Anos ou mais , Antibacterianos/administração & dosagem , Artroplastia de Quadril/efeitos adversos , Cimentos Ósseos/efeitos adversos , Feminino , Prótese de Quadril/efeitos adversos , Humanos , Masculino , Pessoa de Meia-Idade , Amplitude de Movimento Articular , Reoperação/efeitos adversos , Estudos Retrospectivos , Resultado do TratamentoRESUMO
INTRODUCTION: Pulmonary endarterectomy (PEA) is the most effective treatment available for chronic thromboembolic pulmonary hypertension (CTEPH). Patient selection, surgical technique and perioperative management have improved patient outcomes, which are traditionally linked to surgical and center experience. However, optimal perfusion care has not been well defined. The goal of the international survey was to better characterize the contemporary perfusion management of PEA and highlight similarities and controversies. METHOD: The combined caseload of 15 participating centers was 5,066 cases. Topics queried included materials and types of cardiopulmonary bypass (CPB) equipment, choice of prime, fluid management, deep hypothermia strategy, temperature management, treatment of acid-base abnormalities and intraoperative hematocrit as well as anticoagulation management for heparin-induced thrombocytopenia. CONCLUSION: Our assessment could provide a base for further advancement and may help design future studies to elucidate the impact of perfusion in this challenging field.
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Endarterectomia/métodos , Pulmão/fisiopatologia , Perfusão/métodos , Humanos , Inquéritos e Questionários , Resultado do TratamentoRESUMO
In recent years, the minimally invasive joint-preserving implant system has been developed. The main goal of this device is to unload the medial knee compartment without affecting the lateral compartment. The current authors describe a severe metallosis and elevated chromium in serum following implantation of the joint unloading implant system of a 50-year-old male patient, presented to our hospital 3 years after implantation of a KineSpring System into his left knee due to unicompartmental medial osteoarthritis (OA) in an external hospital. Radiographs showed radiological signs for loosening of the screws in the tibia and a progressive OA on the medial and patellofemoral compartments. Revision surgery with removing of the unloading device was performed at our hospital. The intraoperative situs presented a severe metallosis around the device. Five days after revision surgery, the laboratory parameters revealed an elevated value for chromium in serum, while nickel and cobalt values in serum were normal. Reliable clinical data about the long-term results of the KineSpring System is desperately needed. Further studies are warranted to work out the effects of cobalt and chromium levels and further side effects following the implantation of the extra-articular absorber system.