Finite element analysis in asymptomatic, symptomatic, and ruptured abdominal aortic aneurysms: in search of new rupture risk predictors.

OBJECTIVES To compare biomechanical rupture risk parameters of asymptomatic, symptomatic and ruptured abdominal aortic aneurysms (AAA) using finite element analysis (FEA). STUDY DESIGN Retrospective biomechanical single center analysis of asymptomatic, symptomatic, and ruptured AAAs. Comparison of biomechanical parameters from FEA. MATERIALS AND METHODS From 2011 to 2013 computed tomography angiography (CTA) data from 30 asymptomatic, 15 symptomatic, and 15 ruptured AAAs were collected consecutively. FEA was performed according to the successive steps of AAA vessel reconstruction, segmentation and finite element computation. Biomechanical parameters Peak Wall Rupture Risk Index (PWRI), Peak Wall Stress (PWS), and Rupture Risk Equivalent Diameter (RRED) were compared among the three subgroups. RESULTS PWRI differentiated between asymptomatic and symptomatic AAAs (p < .0004) better than PWS (p < .1453). PWRI-dependent RRED was higher in the symptomatic subgroup compared with the asymptomatic subgroup (p < .0004). Maximum AAA external diameters were comparable between the two groups (p < .1355). Ruptured AAAs showed the highest values for external diameter, total intraluminal thrombus volume, PWS, RRED, and PWRI compared with asymptomatic and symptomatic AAAs. In contrast with symptomatic and ruptured AAAs, none of the asymptomatic patients had a PWRI value >1.0. This threshold value might identify patients at imminent risk of rupture. CONCLUSIONS From different FEA derived parameters, PWRI distinguishes most precisely between asymptomatic and symptomatic AAAs. If elevated, this value may represent a negative prognostic factor for asymptomatic AAAs.

Risk-based methodology for parameter calibration of a reservoir flood control model

Flash floods are of major relevance in natural disaster management in the Mediterranean region. In many cases, the damaging effects of flash floods can be mitigated by adequate management of flood control reservoirs. This requires the development of suitable models for optimal operation of reservoirs. A probabilistic methodology for calibrating the parameters of a reservoir flood control model (RFCM) that takes into account the stochastic variability of flood events is presented. This study addresses the crucial problem of operating reservoirs during flood events, considering downstream river damages and dam failure risk as conflicting operation criteria. These two criteria are aggregated into a single objective of total expected damages from both the maximum released flows and stored volumes (overall risk index). For each selected parameter set the RFCM is run under a wide range of hydrologic loads (determined through Monte Carlo simulation). The optimal parameter set is obtained through the overall risk index (balanced solution) and then compared with other solutions of the Pareto front. The proposed methodology is implemented at three different reservoirs in the southeast of Spain. The results obtained show that the balanced solution offers a good compromise between the two main objectives of reservoir flood control management

Outpatient treatment with intravenous antimicrobial therapy and oral levofloxacin in patients with febrile neutropenia and hematological malignancies

The purpose of this study was to evaluate outcomes such as success of the initial therapy, failure of outpatient treatment, and death in outpatient treatment during intravenous antimicrobial therapy in patients with febrile neutropenia (FN) and hematological malignancies. In addition, clinical and laboratory data and the Multinational Association for Supportive Care of Cancer index (MASCC) were compared with failure of outpatient treatment and death. In a retrospective study, we evaluated FN following chemotherapy events that were treated initially with cefepime, with or without teicoplanin and replaced by levofloxacin after 48 h of defervescence in patients with good general conditions and ANC > 500/mm(3). Of the 178 FN episodes occurred in 126 patients, we observed success of the initial therapy in 63.5% of the events, failure of outpatient treatment in 20.8%, and death in 6.2%. The success rate of oral levofloxacin after defervescence was 99% (95 out of 96). Using multivariate analysis, significant risks of failure of outpatient treatment were found to be smoking (odds ratio (OR) 3.14, confidence interval (CI) 1.14-8.66; p = 0.027) and serum creatinine levels > 1.2 mg/dL (OR 7.97, CI 2.19-28.95; p = 0.002). With regard to death, the risk found was oxygen saturation by pulse oximetry < 95% (OR 5.8, IC 1.50-22.56; p = 0.011). Using the MASCC index, 165 events were classified as low risk and 13 as high risk. Failure of outpatient treatment was reported in seven (53.8%) high-risk and 30 (18.2%) low-risk episodes (p = 0.006). In addition, death occurred in seven (4.2%) low-risk and four (30.8%) high-risk events (p = 0.004). Ours results show that MASCC index was able to identify patients with high risk. In addition, non-smoking, serum creatinine levels a parts per thousand currency sign1.2 mg/dL, and oxygen saturation by pulse oximetry a parts per thousand yen95% were protection factors.

Pain and distress reactivity and recovery as early predictors of temperament in toddlers born preterm

Background: Pain reactivity may reflect underlying mechanisms of constitutional aspects of temperament. Aim: To examine whether the neonatal biobehavioral reactivity and recovery responses from pain and distress, as well as the gestational age, the illness severity and the amount of painful procedures undergone the Neonatal Intensive Care Unit (NICU) stay, predict temperament later in toddlerhood, in vulnerable children born preterm. Study design: Prospective-longitudinal study. Subjects: Twenty-six preterm and very low birth weight infants followed from birth to toddlerhood. Outcome measures: Illness severity was assessed with the Clinical Risk Index for Babies (CRIB) score. The medical charts were reviewed prospectively for obtaining the amount of pain exposure in NICU. For assessing the behavioral and cardiac reactivity and recovery from pain and distress, the neonates were evaluated during routine blood collection in the NICU in the first 10 days of life. Pain and distress reactivity and recovery was measured using the Neonatal Facial Coding System score, the duration of crying. and the magnitude of average heart rate. At toddlerhood, mothers answered the Early Childhood Behavior Questionnaire. Results: Higher biobehavioral reactivity to pain and distress predicted higher temperamental Negative Affect, above and beyond gestational age, illness severity and amount of pain exposure in NICU. However, we did not find a predictive relation between gestational age, CRIB score and number of painful procedures undergone NICU and toddler`s temperament. Conclusions: The findings highlight the relevance of the neonatal individual characteristics of reactivity for identifying more vulnerable infants for future problems in biobehavioral regulation. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

Predictable drill-free screw positioning with a graduated 3-dimensional radiographic-surgical guide: A preliminary report

Introduction: Mini-implants are placed in restricted sites, requiring an accurate surgical technique. However, no systematic study has quantified technique accuracy to reliably predict the surgical risks. Therefore, a graduated 3-dimensional radiographic-surgical guide (G-RSG) was proposed, and its inaccuracy and risk index (RI) were estimated. Methods: The sample consisted of 6 subjects (4 male, 2 female), who used mini-implant anchorage. Ten drill-free screws (DFS) were placed by using the G-RSG. The central point of the mesiodistal septum width (SW) was the selected implant site on the presurgical radiograph. The distances between DFS and the adjacent teeth (5-DFS and 6-DFS) were measured to evaluate screw centralization and inaccuracy degree (ID). These distances were statistically compared by independent t tests, and inaccuracy was determined by the expression ID = (5-DFS-6-DFS)/2, which represents deviation of the mini-implant`s final position regarding the central point initially selected. Then SW, ID, and screw diameter (SO) were combined to estimate the surgical risk with RI expressed by RI = SO/SW-ID. Results: The 5-DFS and 6-DFS distances were not significantly different. The ID of the G-RSG was 0.17 mm. The low ID ensured a safe RI (<1) in spite of the restricted SW. Conclusions: The G-RSG accuracy allowed fine prediction of the final DFS position in the inter-radicular septum, with a low RI, which is a helpful tool to estimate surgical risks. (Am J Orthod Dentofacial Orthop 2009; 136: 722-35)

Comparação entre diferentes escores de risco de mortalidade em unidade de tratamento intensivo neonatal

OBJETIVO: Avaliar peso de nascimento e os escores como preditores de mortalidade neonatal em unidade de terapia intensiva neonatal, comparando os seus resultados. MÉTODOS: Foram avaliados 494 recém-nascidos admitidos em uma unidade de terapia intensiva neonatal (UTIN) de um hospital geral de Porto Alegre, RS, logo após o nascimento, entre março de 1997 e junho de 1998. Foram avaliados o peso de nascimento e os escores considerando a variável óbito durante a internação na UTI. Os critérios de exclusão foram: alta ou óbito da UTIN com menos de 24 horas de internação, recém-nascidos cuja internação não ocorreu logo após o nascimento, protocolo de estudo incompleto e malformações congênitas incompatíveis com a vida. Para avaliação do CRIB (Clinical Risk Index for Babies) foram considerados somente os pacientes com peso de nascimento inferior a 1.500 g. Foram calculadas as curvas ROC (Receiver Operating Characteristics Curve) para SNAP (Score for Neonatal Acute), SNAP-PE (Score for Neonatal Acute Physiology Perinatal Extension), SNAP II, SNAP-PE II, CRIB e peso de nascimento. RESULTADOS: Dos 494 pacientes, 44 faleceram (8,9% de mortalidade). Dos 102 recém-nascidos com peso de até 1.500 g, 32 (31,3%) faleceram. As áreas abaixo da curva ROC variaram de 0,81 a 0,94. Todos os escores avaliados mostraram áreas abaixo da curva ROC sem diferenças estatisticamente significativas. Os escores de risco de mortalidade estudados apresentaram um melhor desempenho que o peso de nascimento, especialmente em recém-nascidos com peso de nascimento igual ou menor que 1.500 g. CONCLUSÕES: Todos os escores de mortalidade neonatal apresentaram melhor desempenho e foram superiores ao peso de nascimento como medidores de risco de óbito hospitalar para recém-nascidos internados em UTIN.

Escore CRIB, peso ao nascer e idade gestacional na avaliação do risco de mortalidade neonatal

OBJETIVO: Avaliar a mortalidade dos recém-nascidos de muito baixo peso em uma UTI neonatal conforme as variações do escore CRIB (Clinical Risk Index for Babies), do peso de nascimento e da idade gestacional em determinado período. MÉTODOS: O escore CRIB foi aplicado seqüencial e prospectivamente em todos os recém-nascidos com peso de nascimento <1.500 g e/ou idade gestacional <31 semanas, em maternidade de um hospital universitário de Londrina, no período de janeiro de 1997 a dezembro de 2000. Os critérios de exclusão foram: óbitos antes de 12 horas de vida, os recém- nascidos com malformações congênitas incompatíveis com a sobrevida e os recém- nascidos encaminhados de outros serviços. RESULTADOS: Foram incluídos no estudo 284 recém-nascidos. O peso médio de nascimento foi de 1.148±248 g (mediana =1.180 g); a idade gestacional média foi de 30,2±2,4 semanas (mediana =30,0) e o CRIB médio foi de 3,8±4,4 (mediana =2,0). A mortalidade neonatal foi de 23,2% diferindo conforme peso <750 g (72,7%), IG<29 semanas (57,1%) e CRIB>10 (79,4%). A curva ROC (Receiver Operator Characteristic) para os valores de CRIB, peso de nascimento e idade gestacional gerou áreas sob a curva de 0,88, 0,76 e 0,81, respectivamente. Na análise bivariada, o CRIB, peso e idade gestacional mostraram-se preditores de mortalidade, sendo o escore CRIB>4 o de melhor resultado com sensibilidade de 75,8%, especificidade de 86,7%, valor preditivo positivo de 63,3% e valor preditivo negativo de 92,2%. CONCLUSÕES: Os recém-nascidos com peso de nascimento <750 g, idade gestacional <29 semanas e escore CRIB>10 tiveram maiores taxas de mortalidade, sendo o escore CRIB>4 o que representou melhor poder preditivo quando comparado com peso ao nascer e idade gestacional.

Assistência à saúde e mortalidade de recém-nascidos de muito baixo peso

OBJETIVO: Analisar a mortalidade intra-hospitalar dos recém-nascidos de muito baixo peso, considerando a evolução clínica e os fatores associados à mortalidade. MÉTODOS: Estudo longitudinal que incluiu 360 recém-nascidos com peso entre 500 e 1.500g, em Londrina, Paraná, de 1/1/2002 a 30/6/2004. Os dados foram coletados por meio de entrevistas com as mães, análise dos prontuários e acompanhamento dos recém-nascidos. Para determinação de associação entre as variáveis utilizou-se o teste do qui-quadrado e análise de regressão logística com modelo hierarquizado, com nível de significância de 5%. RESULTADOS: A taxa de mortalidade foi de 32,5%. Na análise bivariada, as variáveis associadas ao óbito oram: não uso de corticosteróide antenatal, ausência de hipertensão arterial/pré-eclampsia, presença de trabalho de parto, parto normal, apresentação não cefálica, Apgar < 3 no primeiro e quinto minutos, Clinical Risk Index for Babies > 5, reanimação na sala de parto, sexo masculino, idade gestacional < 28 semanas, peso < 750g, síndrome do desconforto respiratório, pneumotórax, hemorragia intracraniana e ventilação mecânica. Após regressão logística, permaneceram como fatores de risco: baixa renda per capita, não uso de corticosteróide antenatal e não uso de pressão positiva contínua de vias aéreas. CONCLUSÕES: Mesmo com o uso de tecnologias, a mortalidade observada nos recém-nascidos de muito baixo peso foi alta quando comparada com os países desenvolvidos. A maior utilização do corticosteróide antenatal poderá diminuir a morbidade e mortalidade de recém-nascidos de muito baixo peso.

Avaliação do desempenho de indicadores com base na metodologia ROC (Receiver Operating Characteristic)

Dissertação de mestrado em Bioinformática

Rockburst laboratory tests database - Application of data mining techniques

Rockburst is characterized by a violent explosion of a block causing a sudden rupture in the rock and is quite common in deep tunnels. It is critical to understand the phenomenon of rockburst, focusing on the patterns of occurrence so these events can be avoided and/or managed saving costs and possibly lives. The failure mechanism of rockburst needs to be better understood. Laboratory experiments are undergoing at the Laboratory for Geomechanics and Deep Underground Engineering (SKLGDUE) of Beijing and the system is described. A large number of rockburst tests were performed and their information collected, stored in a database and analyzed. Data Mining (DM) techniques were applied to the database in order to develop predictive models for the rockburst maximum stress (σRB) and rockburst risk index (IRB) that need the results of such tests to be determined. With the developed models it is possible to predict these parameters with high accuracy levels using data from the rock mass and specific project.

Aplicação da metodologia ROC na avaliação de desempenho de índices de gravidade clínica em unidades de neonatologia de Portugal

Tese de Doutoramento em Engenharia Industrial e de Sistemas

Avaliação de projetos de eficiência energética na iluminação pública

Dissertação de mestrado em Engenharia Industrial

Incidence and Predictors of Cardiovascular Complications and Death after Vascular Surgery

AbstractBackground:Patients undergoing arterial vascular surgery are considered at increased risk for post-operative complications.Objective:To assess the incidence and predictors of complications and death, as well as the performance of two models of risk stratification, in vascular surgery.Methods:This study determined the incidence of cardiovascular complications and deaths within 30 days from surgery in adults. Univariate comparison and logistic regression assessed the risk factors associated with the outcomes, and the receiver operating characteristic (ROC) curve assessed the discriminatory capacity of the revised cardiac risk index (RCRI) and vascular study group of New England cardiac risk index (VSG-CRI).Results:141 patients (mean age, 66 years; 65% men) underwent the following surgeries: carotid (15); lower limbs (65); abdominal aorta (56); and others (5). Cardiovascular complications and death occurred within 30 days in 28 (19.9%) and 20 (14.2%) patients, respectively. The risk predictors were: age, obesity, stroke, poor functional capacity, altered scintigraphy, surgery of the aorta, and troponin change. The scores RCRI and VSG-CRI had area under the curve of 0.635 and 0.639 for early cardiovascular complications, and 0.562 and 0.610 for death in 30 days.Conclusion:In this small and selected group of patients undergoing arterial vascular surgery, the incidence of adverse events was elevated. The risk assessment indices RCRI and VSG-CRI did not perform well for complications within 30 days.