CO33 188. Abordaje mínimamente invasivo frente a abordaje estándar en cirugía de recambio valvular aórtico

ObjetivoComparar resultados obtenidos en pacientes sometidos a recambio valvular aórtico aislado por abordaje mínimamente invasivo frente a esternotomía estándar.MétodosEntre enero de 2006 – diciembre de 2011, 524 pacientes fueron sometidos de forma programada a recambio valvular aórtico aislado, de los cuales 454 fueron realizados mediante abordaje estándar (grupo E) y 70 mediante miniesternotomía en «J» (grupo M). Consideradas variables preoperatorias, tiempos de circulación extracorpórea (CEC) y clampaje aórtico, resultados postoperatorios (morbimortalidad, estancias en unidad de cuidados intensivos [UCI] y postoperatoria total) y coste económico global (estancias en UCI, sala, intervención quirúrgica, consumo de fungible, implante y otros recursos).ResultadosLas características preoperatorias de la población fueron similares, sin diferencias significativas en cuanto a edad (68±9 vs 69±8 años) y EuroSCORE I aditivo (6,04±3,00 vs 5,38±2,23) entre grupo E y M, respectivamente. Sin embargo sí hubo diferencias significativas en cuanto a mortalidad (4,2 vs 0%; p < 0,005), tiempo de CEC (95±38 vs 84±21 min; p < 0,001), tiempo de clampaje aórtico (72±28 vs 65±15 min; p < 0,001), días de estancia en UCI (4,31±5,27 vs 3,14±1,2; p < 0,05) y días totales de estancia hospitalaria (9,68±7,6 vs 7,87±4,0; p < 0,05) entre grupo E y M, respectivamente. El grupo M presentó un consumo de 1.771,21 €/paciente inferior al grupo E.ConclusiónLa cirugía mínimamente invasiva para el recambio valvular aórtico puede ser beneficiosa tanto en términos de morbimortalidad como en términos económicos. Dado que el estudio presentado es retrospectivo, creemos que futuros análisis prospectivos aleatorizados serían convenientes para profundizar los hallazgos obtenidos

P15 60. Accidente cerebrovascular tras cirugía coronaria aislada: capacidad predictiva de las escalas de riesgo chads2 y cha2ds2vasc

ObjetivosValidar las escalas de riesgo CHADS2 y CHA2DS2VASC como modelos predictivos de desarrollo de accidente cerebrovascular (ACV) en cirugía coronaria aislada (CCA).MétodosPacientes consecutivos con CCA entre enero de 2003 – octubre de 2011. Puntuaciones CHADS2 y CHA2DS2VASC computadas para todos los pacientes, considerándose variable de resultado la aparición de ACV perioperatorio precoz (primer mes postoperatorio y/o alta hospitalaria). Considerado ACV el evento neurológico con focalidad clínica (ictus/ataque isquémico transitorio [AIT]). Dos modelos específicos ya validados para la predicción de ACV tras CPC, Northern New England Cardiovascular Disease Study Group (NNECDSG) y Multicenter Study of Perioperative Ischemia (McSPI) Research Group, fueron asimismo computados para todos los pacientes y comparados con los previos. La capacidad discriminativa fue cuantificada por el cálculo del área bajo la curva ROC (AUC). Además, dicha capacidad predictiva de los esquemas fue estudiada por distribución de sus puntuaciones en tres estratos atendiendo a la incidencia de ACV postoperatorio: baja (<1%), intermedia (1–3%) y alta (≥ 3%).ResultadosDos mil novecientos diez pacientes, 62 desarrollaron ACV postoperatorio (2,1%). La incidencia de ACV en pacientes igual o mayores de 75 años fue superior (3,9%) que la comparada con los menores de 75 años (1,7%) (odds ratio [OR]: 2,2; p=0,01). La AUC para CHADS2 fue 0,71, CHA2DS2VASC 0,72, NNECDSG 0,69 y McSPI 0,73. NNECDSG y CHA2DS2VASC demostraron mejor asignación de los pacientes a los estratos de bajo y alto riesgo.ConclusionesAmbos sistemas de puntuación CHADS2 y CHA2DS2VASC son modelos utilizados en la práctica clínica cotidiana con capacidad de predicción del desarrollo de ACV postoperatorio tras CCA similar a modelos específicamente preestablecidos

A sliding window-based algorithm for faster transformation of time series into complex networks

A new alternative method to approximate the Visibility Graph (VG) of a time series has been introduced here. It exploits the fact that most of the nodes in the resulting network are not connected to those that are far away from them. This means that the adjacency matrix is almost empty, and its nonzero values are close to the main diagonal. This new method is called Sliding Visibility Graph (SVG). Numerical tests have been performed for several time series, showing a time efficiency that scales linearly with the size of the series [O(N)], in contrast to the original VG that does so quadratically [O(N2)]. This fact is noticeably convenient when dealing with very large time series. The results obtained from the SVG of the studied time series have been compared to the exact values of the original VG. As expected, the SVG outcomes converge very rapidly to the desired ones, especially for random and stochastic series. Also, this method can be extended to the analysis of time series that evolve in real time, since it does not require the entire dataset to perform the analysis but a shorter segment of it. The length segment can remain constant, making possible a simple analysis as the series evolves in time.Comment: 33 pages, 8 figure

Checking complex networks indicators in search of singular episodes of the photochemical smog

A set of indicators derived from the analysis of complex networks have been introduced to identify singularities on a time series. To that end, the Visibility Graphs (VG) from three different signals related to photochemical smog (O3, NO2 concentration and temperature) have been computed. From the resulting complex network, the centrality parameters have been obtained and compared among them. Besides, they have been contrasted to two others that arise from a multifractal point of view, that have been widely used for singularity detection in many fields: the Holder and singularity exponents (specially the first one of them). The outcomes show that the complex network indicators give equivalent results to those already tested, even exhibiting some advantages such as the unambiguity and the more selective results. This suggest a favorable position as supplementary sources of information when detecting singularities in several environmental variables, such as pollutant concentration or temperature.Comment: 32 pages, 7 figure

Visibility graphs of ground-level ozone time series: A multifractal analysis

A recent method based on the concurrence of complex networks and multifractal analyses is applied for the first time to explore ground-level ozone behavior. Ozone time series are converted into complex networks for their posterior analysis. The searched purpose is to check the suitability of this transformation and to see whether some features of these complex networks could constitute a preliminary analysis before the more thorough multifractal formalism. Results show effectively that the exposed transformation stores the original information about the ozone dynamics and gives meaningful knowledge about the time series. Based on these results, the multifractal analysis of the complex networks is performed. Looking at the physical meaning of the multifractal properties (such as fractal dimensions and singularity spectrum), a relationship between those and the degree distribution of the complex networks is found. In addition to all the promising results, this novel connection between time series and complex networks can deal with both stationary and non-stationary time series, overcoming one of the main limitations of multifractal analysis. Therefore, this technique can be regarded as an alternative to give supplementary information within the study of complex signals.Comment: 34 pages, 8 figures, 1 graphical abstrac

Impact of a training program on the surveillance of Clostridioides difficile infection

A high degree of vigilance and appropriate diagnostic methods are required to detect Clostridioides difficile infection (CDI). We studied the effectiveness of a multimodal training program for improving CDI surveillance and prevention. Between 2011 and 2016, this program was made available to healthcare staff of acute care hospitals in Catalonia. The program included an online course, two face-to-face workshops and dissemination of recommendations on prevention and diagnosis. Adherence to the recommendations was evaluated through surveys administered to the infection control teams at the 38 participating hospitals. The incidence of CDI increased from 2.20 cases/10 000 patient-days in 2011 to 3.41 in 2016 (P < 0.001). The number of hospitals that applied an optimal diagnostic algorithm rose from 32.0% to 71.1% (P = 0.002). Hospitals that applied an optimal diagnostic algorithm reported a higher overall incidence of CDI (3.62 vs. 1.92, P < 0.001), and hospitals that were more active in searching for cases reported higher rates of hospital-acquired CDI (1.76 vs. 0.84, P < 0.001). The results suggest that the application of a multimodal training strategy was associated with a significant rise in the reporting of CDI, as well as with an increase in the application of the optimal diagnostic algorithm

Multifractal detrended fluctuation analysis of rainfall time series in the Guadeloupe archipelago

Due to the vulnerability of the Caribbean islands to the climate change issue, it is important to investigate the behavior of rainfall. In addition, the soil of the French West Indies Islands has been contaminated by an insecticide (Chlordecone) whose decontamination is mainly done by drainage water. Thus, it is crucial to investigate the fluctuations of rainfall in these complex environments. In this study, 19 daily rainfall series recorded in different stations of Guadeloupe archipelago from 2005 to 2014 were analyzed with the multifractal detrended fluctuation analysis (MF-DFA) method. The aim of this work is to characterize the long-range correlations and multifractal properties of the time series and to find geographical patterns over the three most important islands. This is the first study that addresses the analysis of multifractal properties of rainfall series in the Caribbean islands. This region is typically characterized by the almost constant influence of the trade winds and a high exposure to changes in the general atmospheric circulation. 12 stations exhibit two different power-law scaling regions in rainfall series, with distinct long-range correlations and multifractal properties for large and small scales. On the contrary, the rest of stations only show a single region of scales for relatively small scales. Hurst exponents reveal persistent long-range correlations. In the most eastern analyzed areas, larger scales exhibit higher persistence than smaller scales, which suggests a relationship between persistence and the highest exposure to the trade winds. Stronger conclusions can be drawn from multifractal spectra, which indicate that most rainfall series have a multifractal nature with higher complexity and degree of multifractality at the smallest scales. Furthermore, a clear dependence of multifractal nature on the latitude is revealed.Comment: 43 pages. 11 figure

Joint multifractal analysis of air temperature, relative humidity and reference evapotranspiration in the middle zone of the Guadalquivir river valley

Previous works have analysed the relationship existing between reference evapotranspiration (ET0) and other climatic variables under a one-at-a-time perturbation condition. However, due to the physical relationships between these climatic variables is advisable to study their joint influence on ET0. The box-counting joint multifractal algorithm describes the relations between variables using relevant information extracted from the data singularities. This work investigated the use of this algorithm to describe the simultaneous behaviour of ET0, calculated by means of Penman-Monteith (PM) equation, and relative humidity (RH) and air temperature (T), influencing on it in the middle zone of the Guadalquivir river valley, Andalusia, southern Spain. The studied cases were grouped according to the fractal dimension values, which were related to their probability of occurrence. The most likely cases were linked to smooth behaviour and weak dependence between variables, both circumstances were detected in the local multifractal analysis. For these cases, the rest of Penman Monteith (PM) equation variables, neither the T nor the RH, seemed to influence on ET0 determination, especially when low T values were involved. By contrast, the least frequent cases were those with variables showing high fluctuations and strong relationship between them. In these situations, when T is low, the ET0 is affected by the rest of PM equation variables. This fact confirmed T as main driver of ET0 because the higher T values the lesser influence of other climate variables on ET0. Joint multifractal analysis shows some limitations when it is applied to large number of variables, the results reported are promising and suggest the convenience of exploring the relationships between ET0 and other climatic variables not considered here with this framework such as wind speed and net radiation.Comment: 40 pages, 10 figure

Can complex networks describe the urban and rural tropospheric O3 dynamics?

Tropospheric ozone (O3) time series have been converted into complex networks through the recent so-called Visibility Graph (VG), using the data from air quality stations located in the western part of Andalusia (Spain). The aim is to apply this novel method to differentiate the behavior between rural and urban regions when it comes to the ozone dynamics. To do so, some centrality parameters of the resulting complex networks have been investigated: the degree, betweenness and shortest path. Some of them are expected to corroborate previous works in order to support the use of this technique; while others to supply new information. Results coincide when describing the difference that tropospheric ozone exhibits seasonally and geographically. It is seen that ozone behavior is fractal, in accordance to previous works. Also, it has been demonstrated that this methodology is able to characterize the divergence encountered between measurements in urban environments and countryside. In addition to that, the promising outcomes of this technique support the use of complex networks for the study of air pollutants dynamics. Particularly, new nuances are offered such as the identification and description of singularities in the signal.Comment: 27 pages, 7 figures, 1 graphical abstrac

Multiplex Visibility Graphs as a complementary tool for describing the relation between ground level O3 and NO2

The usage of multilayer complex networks for the analysis of correlations among environmental variables (such as O3 and NO2 concentrations from the photochemical smog) is investigated in this work. The mentioned technique is called Multiplex Visibility Graphs (MVG). By performing the joint analysis of those layers, the parameters named Average Edge Overlap and Interlayer Mutual Information are extracted, which accounts for the microscopical time coherence and the correlation between the time series behavior, respectively. These parameters point to the possibility of using them independently to describe the correlation between atmospheric pollutants (which could be extended to environmental time series). More precisely the first one of them is considered to be a potential new approach to determine the time required for the correlation of NO2 and O3 to be observed, since it is obtained from the correlation of the pollutants at the smallest time scale. As for the second one, it has been checked that the proposed technique can be used to describe the variation of the correlation between the two gases along the seasons. In short, MVGs parameters are introduced and results show that they could be potentially used in a future for correlation studies, supplementing already existing techniques.Comment: 29 pages, 7 figure