Generation of programmable 3D optical vortex structures through devil's vortex-lens arrays.

Different spatial distributions of optical vortices have been generated and characterized by implementing arrays of devil's vortex lenses in a reconfigurable spatial light modulator. A simple design procedure assigns the preferred position and topological charge value to each vortex in the structure, tuning the desired angular momentum. Distributions with charges and momenta of the opposite sign have been experimentally demonstrated. The angular velocity exhibited by the phase distribution around the focal plane has been visualized, showing an excellent agreement with the simulations. The practical limits of the method, with interest for applications involving particle transfer and manipulation, have been evaluated.

Electronic Structure and Interface Energetics of CuBi2O4 Photoelectrodes.

CuBi2O4 exhibits significant potential for the photoelectrochemical (PEC) conversion of solar energy into chemical fuels, owing to its extended visible-light absorption and positive flat band potential vs the reversible hydrogen electrode. A detailed understanding of the fundamental electronic structure and its correlation with PEC activity is of significant importance to address limiting factors, such as poor charge carrier mobility and stability under PEC conditions. In this study, the electronic structure of CuBi2O4 has been studied by a combination of hard X-ray photoemission spectroscopy, resonant photoemission spectroscopy, and X-ray absorption spectroscopy (XAS) and compared with density functional theory (DFT) calculations. The photoemission study indicates that there is a strong Bi 6s-O 2p hybrid electronic state at 2.3 eV below the Fermi level, whereas the valence band maximum (VBM) has a predominant Cu 3d-O 2p hybrid character. XAS at the O K-edge supported by DFT calculations provides a good description of the conduction band, indicating that the conduction band minimum is composed of unoccupied Cu 3d-O 2p states. The combined experimental and theoretical results suggest that the low charge carrier mobility for CuBi2O4 derives from an intrinsic charge localization at the VBM. Also, the low-energy visible-light absorption in CuBi2O4 may result from a direct but forbidden Cu d-d electronic transition, leading to a low absorption coefficient. Additionally, the ionization potential of CuBi2O4 is higher than that of the related binary oxide CuO or that of NiO, which is commonly used as a hole transport/extraction layer in photoelectrodes. This work provides a solid electronic basis for topical materials science approaches to increase the charge transport and improve the photoelectrochemical properties of CuBi2O4-based photoelectrodes.

Courses on mechanical ventilation in pediatrics: first experience in Spain.

OBJECTIVE: To analyse the initial experience in mechanical ventilation courses held by the Respiratory Group of the Spanish Paediatric Intensive Care Society. MATERIALS AND METHODS: From 2002 to 2006, 15 courses on paediatric mechanical ventilation were held in eight hospitals in Spain, attended by a total of 367 physicians (53.4 % trainees and 46.6 % staff physicians from Paediatrics, Neonatology or Emergency). An initial theoretical written test of 40 questions was completed by participants, followed by short theory classes and practical workshops based on clinical situations, with ventilators and ventilation simulators, with five to seven students per workshop. At the end of the course participants completed a theoretical written test, in which it was considered necessary to answer correctly at least 70% of the questions, a practical evaluation (with assessment grades from 1 to 5) and a written survey about the quality of the course (with assessment grades from 0 to 10). RESULTS: In the initial test, only 20% of students answered 70% of questions correctly, whilst in the final test 93% hit this target, (p < 0.001). In the practical evaluation, 96% of students demonstrated sufficient acquisition of practical skills (grades equal to or greater than 3). In the participant survey, the course methodology was rated at 8.7 +/- 0.5, organisation 8.7 +/- 0.4, teaching staff 9.2 +/- 0.2, theoretical classes 8.7 +/- 0.4 and practical sessions 8.8 +/- 0.3. CONCLUSIONS: Mechanical ventilation courses are a useful educational method for health professionals in theoretical and practical mechanical ventilation.

Incidence study of nosocomial infection in pediatric trauma patients.

In this article we intend to describe the epidemiological profile of nosocomial infection in pediatric patients with multiple trauma. We conducted a prospective study from July to November 2003 in a pediatric teaching hospital in Barcelona. We used US Centers for Disease Control and Prevention standard criteria to define nosocomial infection. Of the 121 patients included in the study, 33% had at least one episode of nosocomial infection, with an incidence rate of 9.9 infections per 100 admissions and 1.1 infections per 100 patient-days. The most frequent episode of nosocomial infection was bacteremia. Coagulase-negative staphylococci were the most common pathogens. Nosocomial infection rates per 100 device-days were 3.2 for bacteremia, 1.6 for respiratory infection and 1.0 for urinary tract infection. These findings suggest the need to evaluate infection control measures aimed at reducing the morbidity associated with infections.

Norovirus-associated encephalitis in a previously healthy 2-year-old girl.

We describe the case of 2-year-old girl with encephalitis associated with norovirus infection. The viral genome was detected in cerebrospinal fluid and stool by reverse transcription polymerase chain reaction. This is the first time in Spain and the second worldwide that the genome of norovirus from the stool sample and 2 cerebrospinal fluid samples were genetically characterized and matched.

Prospective incidence study of nosocomial infections in a pediatric intensive care unit.

BACKGROUND: Nosocomial infections are important causes of substantial morbidity, mortality and prolonged hospital stay in pediatric intensive care units (PICU). METHODS: A prospective surveillance study was performed in the PICU at a university hospital in Barcelona during the 6 months from May through October 2000 to describe the epidemiologic profile of nosocomial infections. Centers for Disease Control and Prevention criteria were used as standard definitions for nosocomial infections. Data including extrinsic risk factors (invasive devices) associated with nosocomial infections were recorded and device-associated infections were calculated for the specific site. RESULTS: During the study period 257 patients were admitted; 15.1% (39) patients had a total of 58 nosocomial infections. The incidence of nosocomial infection was 1.5 per 100 patient-days. Patients with cardiac surgery had the highest nosocomial infection rate, 2.3 per 100 patient-days. Bacteremia (51.7%), respiratory infection (19.0%) and urinary tract infection (17.2%) were the most frequent nosocomial infections observed, and these were associated with use of invasive device. Coagulase-negative staphylococci (39%) and Pseudomonas aeruginosa (24%) were the most common organisms isolated. Nosocomial infection rates per 1000 device days were 23.9 for respiratory infection, 12.4 for bacteremia and 10.7 for urinary tract infection. The durations of hospitalization for patients with and without infection were 22.5 and 9 days, respectively (P < 0.001). CONCLUSIONS: Performance of surveillance highlights the importance of nosocomial infections and their influence in the hospital stay and can guide selection of prevention and control measures to reduce morbidity and mortality in a PICU.

Frequency of apnea and respiratory viruses in infants with bronchiolitis.

The frequency of apnea in infants <12 months of age admitted with acute bronchiolitis was 5.16% (95% confidence interval: 3.94-6.72). Most commonly detected viruses in the 51 apneic infants were respiratory syncytial virus (33.3%), rhinovirus (13.7%) and viral coinfections (23.5%). Young age and prematurity were the main risk factors for apnea independent of the respiratory syncytial virus status. Non-respiratory syncytial virus infants had a higher rate of prematurity.

Clinical risk factors are more relevant than respiratory viruses in predicting bronchiolitis severity.

BACKGROUND: The role of respiratory viruses in the pathogenesis of bronchiolitis was re-evaluated with the use of molecular methods such as PCR for virus detection. Whether specific viruses or the classical clinical risk factors are more important in determining severe bronchiolitis is not well established. AIM: To analyze the specific viruses and clinical variables that can predict severe bronchiolitis at admission. METHODS: Nasopharyngeal aspirates were prospectively collected from 484 children <12 months admitted to the pediatrics ward or PICU at Universitary Hospital Sant Joan de Déu (Barcelona, Spain) for bronchiolitis from October 2007 to October 2008. Clinical and demographic data were collected. Sixteen respiratory viruses were studied using PCR. Severity was assessed with a bronchiolitis clinical score (BCS). RESULTS: Four hundred ten infants that tested positive for respiratory viruses were analyzed. Mixed viral infections did not increase the severity of the disease. Rhinovirus was associated with severe BCS in univariate analysis (P = 0.041), but in the multivariate logistic regression including viruses and clinical data only bronchopulmonary dysplasia (OR 7.2; 95% CI 1.2-43.3), congenital heart disease (OR 4.7; 95% CI 1.1-19.9), prematurity (OR 2.6; 95% CI 1.3-5.1), and fever (OR 1.8, 95% CI 1.1-3.1) showed statistical significance for predicting severe BCS. CONCLUSIONS: Classical clinical risk factors have more weight in predicting a severe BCS in infants with acute bronchiolitis than the involved viruses.

Analysis of human metapneumovirus and human bocavirus viral load.

Viral load (VL) of human metapneumovirus and human bocavirus in infants <12 months admitted for bronchiolitis was analyzed. VL correlated with length of hospital stay in both viruses, human metapneumovirus VL with the duration oxygen therapy and human bocavirus VL inversely with days of respiratory effort before admission. Infants coinfected by other viruses were younger, but no differences were seen regarding VL.

Predicting non-invasive ventilation failure in children from the SpO2/FiO2 (SF) ratio.

PURPOSE: Our objective was to assess whether SpO2/FiO2 (SF) ratio could be a useful NIV outcome predictor in children with acute respiratory failure (ARF) and tried to develop a predictive model of NIV failure. METHODS: Prospective, observational, multicenter study. Episodes of ARF-fulfilling inclusion criteria from 15 January 2010 to 14 January 2011 were treated with NIV according to a pre-established protocol. Clinical variables were collected at baseline and at 1, 2, 6, 12 and 24 h. Failure criterion was the need for endotracheal intubation. Failures were considered as "early" if occurring ≤6 h after NIV initiation, "intermediate" if occurring between 6 and 24 h, and "late" if occurring after 24 h. Variables with a p < 0.1 in univariate analysis corrected by age were included in multivariate analysis. Models were calculated based on multivariate analysis. RESULTS: During the study period, 390 episodes were included. NIV success rate was 81.3 %. Among ARF causes, failure occurred most frequently in ARDS episodes. The failure predictive model for the whole sample included SF ratio at 1 h, age and PRISM III-24 (area under the curve AUC of 0.755). For early NIV failures, SF ratio at 1 h was the only variable within model (AUC 0.748). The analysis of intermediate NIV failures identified 3 variables independently linked to NIV outcome: PRISM III-24, RR decrease at 6 h, and SF ratio at 6 h (AUC 0.895). No model was identified for late NIV failure. CONCLUSIONS: SF ratio is a reliable predictor of early NIV failure in children.

Mechanical ventilation in the pediatric cardiac intensive care unit: the essentials.

Ventilating a child or newborn in the postoperative course after repair of congenital heart disease requires a solid basic understanding of respiratory system mechanics (pressure-volume relationship of the respiratory system and the concept of its time constants) and cardiopulmonary physiology. Furthermore, careful attention has to be paid to avoid damaging the lungs by potentially injurious mechanical ventilation. Optimizing ventilator settings during controlled and assisted ventilation, allowing as early as possible for spontaneous ventilation by still assisting mechanically the patient's respiratory efforts are important features for lung protection, for minimizing potential hemodynamic side effects of positive pressure ventilation, and for early weaning from mechanical ventilation. In the search for being less invasive, the use of noninvasive ventilation in the cardiac intensive care setting is rapidly increasing despite still lacking evidence of its theoretical superiority and requires good knowledge of specific techniques and equipment available for this approach in this setting. This review will address many of these aspects and highlight the essentials to be known when ventilating a child in the Cardiac Intensive Care Unit (CICU).