Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 27
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
BMC Microbiol ; 18(1): 175, 2018 11 23.
Artigo em Inglês | MEDLINE | ID: mdl-30466389

RESUMO

BACKGROUND: The antimicrobial resistance (AMR) phenotypic properties, multiple drug resistance (MDR) gene profiles, and genes related to potential virulence and pathogenic properties of five Enterobacter bugandensis strains isolated from the International Space Station (ISS) were carried out and compared with genomes of three clinical strains. Whole genome sequences of ISS strains were characterized using the hybrid de novo assembly of Nanopore and Illumina reads. In addition to traditional microbial taxonomic approaches, multilocus sequence typing (MLST) analysis was performed to classify the phylogenetic lineage. Agar diffusion discs assay was performed to test antibiotics susceptibility. The draft genomes after assembly and scaffolding were annotated with the Rapid Annotations using Subsystems Technology and RNAmmer servers for downstream analysis. RESULTS: Molecular phylogeny and whole genome analysis of the ISS strains with all publicly available Enterobacter genomes revealed that ISS strains were E. bugandensis and similar to the type strain EB-247T and two clinical isolates (153_ECLO and MBRL 1077). Comparative genomic analyses of all eight E. bungandensis strains showed, a total of 4733 genes were associated with carbohydrate metabolism (635 genes), amino acid and derivatives (496 genes), protein metabolism (291 genes), cofactors, vitamins, prosthetic groups, pigments (275 genes), membrane transport (247 genes), and RNA metabolism (239 genes). In addition, 112 genes identified in the ISS strains were involved in virulence, disease, and defense. Genes associated with resistance to antibiotics and toxic compounds, including the MDR tripartite system were also identified in the ISS strains. A multiple antibiotic resistance (MAR) locus or MAR operon encoding MarA, MarB, MarC, and MarR, which regulate more than 60 genes, including upregulation of drug efflux systems that have been reported in Escherichia coli K12, was also observed in the ISS strains. CONCLUSION: Given the MDR results for these ISS Enterobacter genomes and increased chance of pathogenicity (PathogenFinder algorithm with > 79% probability), these species pose important health considerations for future missions. Thorough genomic characterization of the strains isolated from ISS can help to understand the pathogenic potential, and inform future missions, but analyzing them in in-vivo systems is required to discern the influence of microgravity on their pathogenicity.


Assuntos
Farmacorresistência Bacteriana Múltipla , Enterobacter/efeitos dos fármacos , Enterobacter/genética , Infecções por Enterobacteriaceae/microbiologia , Astronave , Antibacterianos/farmacologia , Enterobacter/classificação , Enterobacter/isolamento & purificação , Genoma Bacteriano , Genômica , Humanos , Testes de Sensibilidade Microbiana , Tipagem de Sequências Multilocus , Filogenia , Astronave/estatística & dados numéricos , Sequenciamento Completo do Genoma
2.
Sci Total Environ ; 630: 1309-1323, 2018 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-29554751

RESUMO

Efficient utilization of the limited Water, Energy, and Food (WEF) resources in stressed transboundary river basins requires understanding their interlinkages in different transboundary cooperation conditions. The Blue Nile Basin, a transboundary river basin between Ethiopia and Sudan, is used to illustrate the impacts of cooperation between riparian countries on the Water-Energy-Food nexus (WEF nexus). These impacts are quantified and evaluated using a daily model that simulates hydrological processes, irrigation water requirements, and water allocation to hydro-energy generation and irrigation water supply. Satellite-based rainfall data are evaluated and applied as a boundary condition to model the hydrological processes. The model is used to determine changes in the long-term economic gain (i.e. after infrastructure development plans are implemented and in steady operation) for each of Sudan and Ethiopia independently, and for the Blue Nile Basin from WEF in 120 scenarios. Those scenarios result from combinations of three cooperation states: unilateral action, coordination, and collaboration; and infrastructure development settings including the Grand Ethiopian Renaissance Dam and planned irrigation schemes in Sudan. The results show that the economic gain of the Blue Nile Basin from WEF increases with raising the cooperation level between Ethiopia and Sudan to collaboration. However, the economic gain of each riparian country does not necessarily follow the same pattern as the economic gain of the basin.

3.
Ultrasonics ; 84: 187-200, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29154046

RESUMO

Ultrasonic wave methods constitute the leading physical mechanism for nondestructive evaluation (NDE) and structural health monitoring (SHM) of solid composite materials, such as carbon fiber reinforced polymer (CFRP) laminates. Computational models of ultrasonic wave excitation, propagation, and scattering in CFRP composites can be extremely valuable in designing practicable NDE and SHM hardware, software, and methodologies that accomplish the desired accuracy, reliability, efficiency, and coverage. The development and application of ultrasonic simulation approaches for composite materials is an active area of research in the field of NDE. This paper presents comparisons of guided wave simulations for CFRP composites implemented using four different simulation codes: the commercial finite element modeling (FEM) packages ABAQUS, ANSYS, and COMSOL, and a custom code executing the Elastodynamic Finite Integration Technique (EFIT). Benchmark comparisons are made between the simulation tools and both experimental laser Doppler vibrometry data and theoretical dispersion curves. A pristine and a delamination type case (Teflon insert in the experimental specimen) is studied. A summary is given of the accuracy of simulation results and the respective computational performance of the four different simulation tools.

4.
Water Resour Res ; 54(11): 9224-9254, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30774162

RESUMO

A water resource modeling process is demonstrated to support multistakeholder negotiations over transboundary management of the Nile River. This process addresses the challenge of identifying management options of new hydraulic infrastructure that potentially affects downstream coriparian nations and how the management of existing infrastructure can be adapted. The method includes an exploration of potential management decisions using a multiobjective evolutionary algorithm, intertwined with an iterative process of formulating cooperative strategies to overcome technical and political barriers faced in a transboundary negotiation. The case study is the addition of the Grand Ethiopian Renaissance Dam (GERD) and considers how its operation may be coordinated with adaptations to the operations of Egypt's High Aswan Dam. The results demonstrate that a lack of coordination is likely to be harmful to downstream riparians and suggest that adaptations to infrastructure in Sudan and Egypt can reduce risks to water supplies and energy generation. Although risks can be substantially reduced by agreed releases from the GERD and basic adaptations to the High Aswan Dam, these measures are still insufficient to assure that no additional risk is assumed by Egypt. The method then demonstrates how improvements to water security for both downstream riparians can be achieved through dynamic adaptation of the operation of the GERD during drought conditions. Finally, the paper demonstrates how the robustness of potential management arrangements can be evaluated considering potential effects of climate change, including increased interannual variability and highly uncertain changes such as increases in the future persistence of droughts.

5.
Cochrane Database Syst Rev ; 10: CD003666, 2017 10 17.
Artigo em Inglês | MEDLINE | ID: mdl-29039883

RESUMO

BACKGROUND: Damage caused by lung overdistension (volutrauma) has been implicated in the development of bronchopulmonary dysplasia (BPD). Modern neonatal ventilation modes can target a set tidal volume as an alternative to traditional pressure-limited ventilation (PLV) using a fixed inflation pressure. Volume-targeted ventilation (VTV) aims to produce a more stable tidal volume in order to reduce lung damage and stabilise the partial pressure of carbon dioxide (pCO2). OBJECTIVES: To determine whether VTV compared with PLV leads to reduced rates of death and death or BPD in newborn infants and to determine whether use of VTV affected outcomes including air leak, cranial ultrasound findings and neurodevelopment. SEARCH METHODS: We used the standard search strategy of Cochrane Neonatal to search the Cochrane Central Register of Controlled Trials (CENTRAL 2016, Issue 12), MEDLINE via PubMed (1966 to 13 January 2017), Embase (1980 to 13 January 2017) and CINAHL (1982 to 13 January 2017). We also searched clinical trials databases, conference proceedings and the reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials. We contacted the principal investigators of studies to obtain supplementary information. SELECTION CRITERIA: Randomised and quasi-randomised trials comparing VTV versus PLV in infants of less than 44 weeks' postmenstrual age and reporting clinically relevant outcomes. DATA COLLECTION AND ANALYSIS: We assessed risk of bias for each trial using Cochrane methodology. We evaluated quality of evidence for each outcome using GRADE criteria. We tabulated mortality, rates of BPD, short-term clinical outcomes and long-term developmental outcomes. STATISTICS: for categorical outcomes, we calculated typical estimates for risk ratios (RR), risk differences (RD) and number needed to treat for an additional beneficial outcome (NNTB). For continuous variables, we calculated typical estimates for mean differences (MD). We used 95% confidence intervals (CI) and assumed a fixed-effect model for meta-analysis. MAIN RESULTS: Twenty randomised trials met our inclusion criteria; 16 parallel trials (977 infants) and four cross-over trials (88 infants). No studies were blinded and the quality of evidence for outcomes assessed varied from moderate to low.We found no difference in the primary outcome, death before hospital discharge, between VTV modes versus PLV modes (typical RR 0.75, 95% CI 0.53 to 1.07; low quality evidence). However, there was moderate quality evidence that the use of VTV modes resulted in a reduction in the primary outcome, death or BPD at 36 weeks' gestation (typical RR 0.73, 95% CI 0.59 to 0.89; typical NNTB 8, 95% CI 5 to 20) and the following secondary outcomes: rates of pneumothorax (typical RR 0.52, 95% CI 0.31 to 0.87; typical NNTB 20, 95% CI 11 to 100), mean days of mechanical ventilation (MD -1.35 days, 95% CI -1.83 to -0.86), rates of hypocarbia (typical RR 0.49, 95% CI 0.33 to 0.72; typical NNTB 3, 95% CI 2 to 5), rates of grade 3 or 4 intraventricular haemorrhage (typical RR 0.53, 95% CI 0.37 to 0.77; typical NNTB 11, 95% CI 7 to 25) and the combined outcome of periventricular leukomalacia with or without grade 3 or 4 intraventricular haemorrhage (typical RR 0.47, 95% CI 0.27 to 0.80; typical NNTB 11, 95% CI 7 to 33). VTV modes were not associated with any increased adverse outcomes. AUTHORS' CONCLUSIONS: Infants ventilated using VTV modes had reduced rates of death or BPD, pneumothoraces, hypocarbia, severe cranial ultrasound pathologies and duration of ventilation compared with infants ventilated using PLV modes. Further studies are needed to identify whether VTV modes improve neurodevelopmental outcomes and to compare and refine VTV strategies.


Assuntos
Displasia Broncopulmonar/prevenção & controle , Ventilação com Pressão Positiva Intermitente/métodos , Displasia Broncopulmonar/etiologia , Humanos , Recém-Nascido , Recém-Nascido Prematuro , Ventilação com Pressão Positiva Intermitente/mortalidade , Pressão , Ensaios Clínicos Controlados Aleatórios como Assunto , Volume de Ventilação Pulmonar
6.
Arch Dis Child Fetal Neonatal Ed ; 102(1): F31-F36, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27634820

RESUMO

OBJECTIVE: To assess the performance of a novel algorithm for automated oxygen control using a simulation of oxygenation founded on in vivo data from preterm infants. METHODS: A proportional-integral-derivative (PID) control algorithm was enhanced by (i) compensation for the non-linear SpO2-PaO2 relationship, (ii) adaptation to the severity of lung dysfunction and (iii) error attenuation within the target range. Algorithm function with and without enhancements was evaluated by iterative linking with a computerised simulation of oxygenation. Data for this simulation (FiO2 and SpO2 at 1 Hz) were sourced from extant recordings from preterm infants (n=16), and converted to a datastream of values for ventilation:perfusion ratio and shunt. Combination of this datastream second by second with the FiO2 values from the algorithm under test produced a sequence of novel SpO2 values, allowing time in the SpO2 target range (91%-95%) and in various degrees of hypoxaemia and hyperoxaemia to be determined. A PID algorithm with 30 s lockout after each FiO2 adjustment, and a proportional-derivative (PD) algorithm were also evaluated. RESULTS: Separate addition of each enhancing feature to the PID algorithm showed a benefit, but not with uniformly positive effects. The fully enhanced algorithm was optimal for the combination of targeting the desired SpO2 range and avoiding time in, and episodes of, hypoxaemia and hyperoxaemia. This algorithm performed better than one with a 30 s lockout, and considerably better than PD control. CONCLUSIONS: An enhanced PID algorithm was very effective for automated oxygen control in a simulation of oxygenation, and deserves clinical evaluation.


Assuntos
Algoritmos , Automação/métodos , Doenças do Prematuro/terapia , Recém-Nascido Prematuro , Oxigenoterapia/métodos , Oxigênio/administração & dosagem , Respiração Artificial/métodos , Feminino , Humanos , Recém-Nascido , Masculino , Oximetria
7.
J Clin Monit Comput ; 31(2): 427-433, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26897033

RESUMO

Automated control of inspired oxygen for newborn infants is an emerging technology, currently limited by reliance on a single input signal (oxygen saturation, SpO2). This is while other signals that may herald the onset of hypoxic events or identify spurious hypoxia are not usually utilised. We wished to assess the frequency of apnoea, loss of circuit pressure and/or motion artefact in proximity to hypoxic events in preterm infants on non-invasive ventilation. Hypoxic events (SpO2 < 80 %) were identified using a previously acquired dataset obtained from preterm infants receiving non-invasive ventilation. Events with concomitant apnoea, loss of circuit pressure or oximetry motion artefact were annotated, and the frequency of each of these factors was determined. The effect of duration and timing of apnoea on the characteristics of the associated hypoxic events was studied. Among 1224 hypoxic events, 555 (45 %) were accompanied by apnoea, 31 (2.5 %) by loss of circuit pressure and 696 (57 %) by motion artefact, while for 224 (18 %) there were no concomitant factors identified. Respiratory pauses of longer duration (>15 s) preceding hypoxic events, were associated with a relatively slow decline in SpO2 and more prolonged hypoxia compared to shorter pauses. Hypoxic events are frequently accompanied by respiratory pauses and/or motion artefact. Real-time monitoring and input of respiratory waveform may thus improve the function of automated oxygen controllers, allowing pre-emptive responses to respiratory pauses. Furthermore, use of motion-resistant oximeters and plethysmographic waveform assessment procedures will help to optimise feedback control of inspired oxygen delivery.


Assuntos
Hipóxia , Ventilação não Invasiva/instrumentação , Oximetria/instrumentação , Processamento de Sinais Assistido por Computador , Algoritmos , Apneia , Artefatos , Gráficos por Computador , Pressão Positiva Contínua nas Vias Aéreas , Humanos , Recém-Nascido , Recém-Nascido Prematuro , Doenças do Prematuro/terapia , Movimento (Física) , Ventilação não Invasiva/métodos , Oximetria/métodos , Oxigênio , Respiração , Interface Usuário-Computador
8.
Arch Dis Child Fetal Neonatal Ed ; 102(1): F37-F43, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27573518

RESUMO

OBJECTIVE: To evaluate the performance of a novel rapidly responsive proportional-integral-derivative (PID) algorithm for automated oxygen control in preterm infants with respiratory insufficiency. DESIGN: Interventional study of a 4-hour period of automated oxygen control compared with combined data from two flanking periods of manual control (4 hours each). SETTING: Neonatal intensive care unit. PARTICIPANTS: Preterm infants (n=20) on non-invasive respiratory support and supplemental oxygen, with oxygen saturation (SpO2) target range 90%-94% (manual control) and 91%-95% (automated control). Median gestation at birth 27.5 weeks (IQR 26-30 weeks), postnatal age 8.0 (1.8-34) days. INTERVENTION: Automated oxygen control using a standalone device, receiving SpO2 input from a standard oximeter and computing alterations to oxygen concentration that were actuated with a modified blender. The PID algorithm was enhanced to avoid iatrogenic hyperoxaemia and adapt to the severity of lung dysfunction. MAIN OUTCOME MEASURE: Proportion of time in the SpO2 target range, or above target range when in air. RESULTS: Automated oxygen control resulted in more time in the target range or above in air (manual 56 (48-63)% vs automated 81 (76-90)%, p<0.001) and less time at both extremes of oxygenation. Prolonged episodes of hypoxaemia and hyperoxaemia were virtually eliminated. The control algorithm showed benefit in every infant. Manual changes to oxygen therapy were infrequent during automated control (0.24/hour vs 2.3/hour during manual control), and oxygen requirements were unchanged (automated control period 27%, manual 27% and 26%, p>0.05). CONCLUSIONS: The novel PID algorithm was very effective for automated oxygen control in preterm infants, and deserves further investigation.


Assuntos
Pressão Positiva Contínua nas Vias Aéreas/métodos , Doenças do Prematuro/terapia , Recém-Nascido Prematuro , Unidades de Terapia Intensiva Neonatal , Oxigenoterapia/métodos , Oxigênio/administração & dosagem , Insuficiência Respiratória/terapia , Algoritmos , Automação , Estudos Cross-Over , Feminino , Seguimentos , Humanos , Recém-Nascido , Masculino , Oximetria/métodos , Resultado do Tratamento
9.
Neonatology ; 109(1): 37-43, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26554825

RESUMO

BACKGROUND: Oxygen saturation (SpO2) targeting in the preterm infant may be improved with a better understanding of the SpO2 responses to changes in inspired oxygen (FiO2). OBJECTIVE: We investigated the first-order FiO2-SpO2 relationship, aiming to quantify the parameters governing that relationship, the influences on these parameters and their variability. METHODS: In recordings of FiO2 and SpO2 from preterm infants on continuous positive airway pressure and supplemental oxygen, we identified unique FiO2 adjustments and mapped the subsequent SpO2 responses. For responses identified as first-order, the delay, time constant and gain parameters were determined. Clinical and physiological predictors of these parameters were sought in regression analysis, and intra- and inter-subject variability was evaluated. RESULTS: In 3,788 h of available data from 47 infants at 31 (28-33) post-menstrual weeks [median (interquartile range)], we identified 993 unique FiO2 adjustments followed by a first-order SpO2 response. All response parameters differed between FiO2 increments and decrements, with increments having a shorter delay, longer time constant and higher gain [2.9 (1.7-4.8) vs. 1.3 (0.58-2.6), p < 0.05]. Gain was also higher in less mature infants and in the setting of recent SpO2 instability, and was diminished with increasing severity of lung dysfunction. Intra-subject variability in all parameters was prominent. CONCLUSIONS: First-order SpO2 responses show variable gain, influenced by the direction of FiO2 adjustment and the severity of lung disease, as well as substantial intra-subject parameter variability. These findings should be taken into account in adjustment of FiO2 for SpO2 targeting in preterm infants.


Assuntos
Pressão Positiva Contínua nas Vias Aéreas/métodos , Recém-Nascido Prematuro , Oximetria/métodos , Oxigenoterapia/métodos , Oxigênio/análise , Humanos , Recém-Nascido
10.
Arch Dis Child Fetal Neonatal Ed ; 100(5): F436-8, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26054970

RESUMO

Oxygen saturation (SpO2) signal dropout leaves caregivers without a reliable measure to guide oxygen therapy. We studied SpO2 dropout in preterm infants on continuous positive airway pressure, noting the SpO2 values at signal loss and recovery and thus the resultant change in SpO2, and the factors influencing this parameter. In 32 infants of median gestation 26 weeks, a total of 3932 SpO2 dropout episodes were identified (1.1 episodes/h). In the episodes overall, SpO2 decreased by 1.1%, with the SpO2 change influenced by starting SpO2 (negative correlation), but not dropout duration. For episodes starting in hypoxia (SpO2 <85%), SpO2 recovered at a median of 3.2% higher than at SpO2 dropout, with a downward trajectory in a quarter of cases. We conclude that after signal dropout SpO2 generally recovers in a relative normoxic range. Blind FiO2 adjustments are thus unlikely to be of benefit during most SpO2 dropout episodes.


Assuntos
Pressão Positiva Contínua nas Vias Aéreas , Hiperóxia/prevenção & controle , Hipóxia/prevenção & controle , Doenças do Prematuro/prevenção & controle , Oximetria/instrumentação , Falha de Equipamento , Humanos , Recém-Nascido , Recém-Nascido Prematuro
11.
J Appl Physiol (1985) ; 117(5): 535-43, 2014 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-24994883

RESUMO

At birth, the transition to newborn life is triggered by lung aeration, which stimulates a large increase in pulmonary blood flow (PBF). Current theories predict that the increase in PBF is spatially related to ventilated lung regions as they aerate after birth. Using simultaneous phase-contrast X-ray imaging and angiography we investigated the spatial relationships between lung aeration and the increase in PBF after birth. Six near-term (30-day gestation) rabbits were delivered by caesarean section, intubated and an intravenous catheter inserted, before they were positioned for X-ray imaging. During imaging, iodine was injected before ventilation onset, after ventilation of the right lung only, and after ventilation of both lungs. Unilateral ventilation increased iodine levels entering both left and right pulmonary arteries (PAs) and significantly increased heart rate, iodine ejection per beat, diameters of both left and right PAs, and number of visible vessels in both lungs. Within the 6th intercostal space, the mean gray level (relative measure of iodine level) increased from 68.3 ± 11.6 and 70.3 ± 7.5%·s to 136.3 ± 22.6 and 136.3 ± 23.7%·s in the left and right PAs, respectively. No differences were observed between vessels in the left and right lungs, despite the left lung not initially being ventilated. The increase in PBF at birth is not spatially related to lung aeration allowing a large ventilation/perfusion mismatch, or pulmonary shunting, to occur in the partially aerated lung at birth.


Assuntos
Animais Recém-Nascidos/fisiologia , Relação Ventilação-Perfusão/fisiologia , Angiografia , Animais , Feminino , Frequência Cardíaca/fisiologia , Iodo/metabolismo , Pulmão/diagnóstico por imagem , Gravidez , Artéria Pulmonar/anatomia & histologia , Artéria Pulmonar/diagnóstico por imagem , Artéria Pulmonar/fisiologia , Veias Pulmonares/anatomia & histologia , Veias Pulmonares/diagnóstico por imagem , Veias Pulmonares/fisiologia , Coelhos
13.
J Pediatr ; 164(4): 730-736.e1, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24433828

RESUMO

OBJECTIVE: The precision of oxygen saturation (SpO2) targeting in preterm infants on continuous positive airway pressure (CPAP) is incompletely characterized. We therefore evaluated SpO2 targeting in infants solely receiving CPAP, aiming to describe their SpO2 profile, to document the frequency of prolonged hyperoxia and hypoxia episodes and of fraction of inspired oxygen (FiO2) adjustments, and to explore the relationships with neonatal intensive care unit operational factors. STUDY DESIGN: Preterm infants <37 weeks' gestation in 2 neonatal intensive care units were studied if they were receiving CPAP and in supplemental oxygen at the beginning of each 24-hour recording. SpO2, heart rate, and FiO2 were recorded (sampling interval 1-2 seconds). We measured the proportion of time spent in predefined SpO2 ranges, the frequency of prolonged episodes (≥30 seconds) of SpO2 deviation, and the effect of operational factors including nurse-patient ratio. RESULTS: A total of 4034 usable hours of data were recorded from 45 infants of gestation 30 (27-32) weeks (median [IQR]). When requiring supplemental oxygen, infants were in the target SpO2 range (88%-92%) for only 31% (19%-39%) of total recording time, with 48 (6.9-90) episodes per 24 hours of severe hyperoxia (SpO2 ≥98%), and 9.0 (1.6-21) episodes per 24 hours of hypoxia (SpO2 <80%). An increased frequency of prolonged hyperoxia in supplemental oxygen was noted when nurses were each caring for more patients. Adjustments to FiO2 were made 25 (16-41) times per day. CONCLUSION: SpO2 targeting is challenging in preterm infants receiving CPAP support, with a high proportion of time spent outside the target range and frequent prolonged hypoxic and hyperoxic episodes.


Assuntos
Pressão Positiva Contínua nas Vias Aéreas/métodos , Recém-Nascido Prematuro , Oxigênio/administração & dosagem , Feminino , Humanos , Hiperóxia/metabolismo , Hipóxia/metabolismo , Recém-Nascido , Masculino , Oxigênio/metabolismo , Estudos Prospectivos
14.
Conserv Biol ; 27(6): 1410-20, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24033460

RESUMO

Despite the high profile of amphibian declines and the increasing threat of drought and fragmentation to aquatic ecosystems, few studies have examined long-term rates of change for a single species across a large geographic area. We analyzed growth in annual egg-mass counts of the Columbia spotted frog (Rana luteiventris) across the northwestern United States, an area encompassing 3 genetic clades. On the basis of data collected by multiple partners from 98 water bodies between 1991 and 2011, we used state-space and linear-regression models to measure effects of patch characteristics, frequency of summer drought, and wetland restoration on population growth. Abundance increased in the 2 clades with greatest decline history, but declined where populations are considered most secure. Population growth was negatively associated with temporary hydroperiods and landscape modification (measured by the human footprint index), but was similar in modified and natural water bodies. The effect of drought was mediated by the size of the water body: populations in large water bodies maintained positive growth despite drought, whereas drought magnified declines in small water bodies. Rapid growth in restored wetlands in areas of historical population declines provided strong evidence of successful management. Our results highlight the importance of maintaining large areas of habitat and underscore the greater vulnerability of small areas of habitat to environmental stochasticity. Similar long-term growth rates in modified and natural water bodies and rapid, positive responses to restoration suggest pond construction and other forms of management can effectively increase population growth. These tools are likely to become increasingly important to mitigate effects of increased drought expected from global climate change. Papeles de las Características del Fragmento, Frecuencia de Sequía y Restauración en las Tendencias a Largo Plazo de un Anfibio Ampliamente Distribuido.


Assuntos
Conservação dos Recursos Naturais , Secas , Ranidae/fisiologia , Animais , Ecossistema , Geografia , Densidade Demográfica , Dinâmica Populacional
15.
Pediatr Res ; 73(6): 734-41, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23478642

RESUMO

BACKGROUND: We investigated the effects of positive end-expiratory pressure (PEEP) and tidal volume (VT) on lung aeration, pulmonary mechanics, and the distribution of ventilation immediately after birth using a preterm rabbit model. METHODS: Sixty preterm rabbits (27 d) received volume-targeted positive pressure ventilation from birth, with one of the 12 combinations of PEEP (0, 5, 8, or 10 cm H2O) and VT (4, 8, or 12 ml/kg). Outcomes included functional residual capacity (FRC), peak inflating pressure (PIP), dynamic compliance (Cd), and distribution of ventilation. RESULTS: Increasing PEEP from 0 to 10 cm H2O increased FRC by 4 ml/kg, increased Cd by 0.2 ml/kg/cm H2O, and reduced PIP by 5 cm H2O. Increasing VT from 4 to 12 ml/kg increased FRC by 2 ml/kg, increased Cd by 0.3 ml/kg/cm H2O, and increased PIP by 4 cmH2O. No effect of VT on FRC occurred at 0 or 5 PEEP, and no effect of PEEP occurred at VT = 4 ml/kg. At 0 PEEP, increasing VT increased the proportion of gas entering the smaller apical regions, whereas at 10 PEEP, increasing VT increased the proportion of gas entering basal regions, from 47% to 63%. CONCLUSION: Both PEEP and VT have independent, additive effects on FRC, lung mechanics, and the distribution of ventilation during the immediate newborn period.


Assuntos
Pulmão/fisiopatologia , Oxigênio/metabolismo , Respiração com Pressão Positiva , Volume de Ventilação Pulmonar , Capacidade Pulmonar Total , Animais , Animais Recém-Nascidos , Coelhos
16.
J Clin Pathol ; 65(5): 403-8, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22447915

RESUMO

AIMS: (1) To compare the use of scanned virtual slide images (virtual microscopy) with glass slides (conventional microscopy) in the assessment of morphological characteristics of breast cancers within the setting of the Prospective study of Outcomes in Sporadic versus Hereditary breast cancer (POSH), involving a cohort of women under 40 years of age, presenting with breast cancer. (2) To assess the acceptability to histopathologists of the use of virtual slide images. METHODS: 13 histopathologists from the UK and Australia participated in the POSH pathology review. The observers were asked to assess multiple morphological features such as tumour grade and type. Comparisons were made for a single observer using both virtual images and glass slides. Intra- and inter-observer variability was calculated using the κ statistic and a comparison was made between the use of each image modality. RESULTS: Diagnostic performance with virtual slides was comparable to conventional microscopic assessment, with the measurement of agreement best for vascular invasion, necrosis and the presence of a central scar (κ=0.37-0.78), and poor for more subjective parameters such as pleomorphism, stroma, the nature of the tumour border and the degree of lymphocytic infiltrate (κ=0.1). CONCLUSION: Virtual slides represent an acceptable methodology for central review of breast cancer histopathology and can circumvent the need for either travel to view material, or the potential problems of sending it by post.


Assuntos
Neoplasias da Mama/diagnóstico , Diagnóstico por Imagem/métodos , Internet , Patologia Cirúrgica/métodos , Telepatologia/métodos , Adulto , Austrália , Neoplasias da Mama/genética , Diagnóstico por Imagem/estatística & dados numéricos , Feminino , Humanos , Invasividade Neoplásica/diagnóstico , Variações Dependentes do Observador , Patologia Cirúrgica/estatística & dados numéricos , Estudos Prospectivos , Software , Telepatologia/estatística & dados numéricos , Reino Unido
17.
Neonatology ; 100(3): 219-27, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21701210

RESUMO

BACKGROUND: The causes of bronchopulmonary dysplasia (BPD) are multifactorial. Overdistension of the lung (volutrauma) is considered an important contribution. As an alternative to traditional pressure-limited ventilation (PLV), modern neonatal ventilators offer modes which can target a set tidal volume. OBJECTIVES: To determine whether volume-targeted neonatal ventilation, compared with PLV, reduces death or BPD. METHODS: We performed a systematic review and meta-analysis using the methodology of the Neonatal Review Group of the Cochrane Collaboration. A comprehensive literature search was undertaken, and data for prespecified outcomes were combined where appropriate using the fixed effects model. RESULTS: Nine trials were eligible. Volume-targeted ventilation resulted in a reduction in: the combined outcome of death or BPD [typical relative risk, RR, 0.73 (95% confidence interval, 0.57-0.93), numbers needed to treat, NNT, 8 (95% CI 5-33)], the incidence of pneumothorax [typical RR 0.46 (95% CI 0.25-0.84), NNT 17 (95% CI 10-100)], days of ventilation [weighted mean difference 0.8 days (log-transformed data, p = 0.05)], hypocarbia (pCO(2) <35 mm Hg/4.7 kPa); [typical RR 0.56 (95% CI 0.33-0.96), NNT 4 (95% CI 2-25)], and the combined outcome of periventricular leukomalacia or grade 3-4 intraventricular hemorrhage [typical RR 0.48 (95% CI 0.28-0.84), NNT 11 (95% CI 7-50)]. CONCLUSIONS: Compared with PLV, infants ventilated using volume-targeted ventilation had reduced death/BPD, duration of ventilation, pneumothoraces, hypocarbia and periventricular leukomalacia/severe intraventricular hemorrhage. Further studies are needed to assess neurodevelopmental outcomes.


Assuntos
Displasia Broncopulmonar/prevenção & controle , Recém-Nascido Prematuro/fisiologia , Respiração com Pressão Positiva/métodos , Ventilação Pulmonar/fisiologia , Insuficiência Respiratória/terapia , Volume de Ventilação Pulmonar/fisiologia , Displasia Broncopulmonar/etiologia , Displasia Broncopulmonar/mortalidade , Humanos , Recém-Nascido , Complacência Pulmonar , Pneumotórax/etiologia , Pneumotórax/mortalidade , Pneumotórax/prevenção & controle , Respiração com Pressão Positiva/efeitos adversos , Ensaios Clínicos Controlados Aleatórios como Assunto , Insuficiência Respiratória/etiologia , Insuficiência Respiratória/fisiopatologia , Taxa de Sobrevida
18.
J Paediatr Child Health ; 47(4): 211-6, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21244551

RESUMO

AIM: The Dräger Babylog 8000plus ventilator (Dräger Medical Systems, Lübeck, Germany) can provide both conventional and high-frequency ventilation (HFV). Dräger recommends specific circuits for each of these modes. We investigated the performance of the Babylog ventilator in HFV mode when used with the recommended circuits for both conventional and HFV. METHODS: The Fisher and Paykel RT235 (conventional; Fisher and Paykel Healthcare, Auckland, New Zealand) and Hytrel (HFV; Fisher and Paykel Healthcare) circuits were studied using a 50-mL test lung. Tidal volume, high-frequency minute volume and ventilator alarms were compared at 100 combinations of mean airway pressures (10-16 cm H2O), frequencies (6-14 Hz) and amplitudes (20-60%). RESULTS: Tidal volume with the two circuits differed by < 5% for tidal volumes ≤ 2.5 mL. Above this, tidal volumes delivered with the HFV circuit were up to 15% more than that obtained with the conventional ventilation circuit, and high-frequency minute volume differed by up to 30%. With the exception of the highest tidal/minute volumes, the tidal volume delivered using the HFV circuit could also be achieved with adjusted frequency or amplitude when using the conventional circuit. More 'pressure measurement out of range' alarms were noted with the conventional ventilation circuit, particularly at mean airway pressure ≥ 14 cm H2O and frequency ≤ 10 Hz. CONCLUSIONS: The conventional ventilation circuit may allow delivery of adequate tidal volume for some infants. Where requirements are higher, the HFV circuit allows the Babylog to deliver higher tidal volumes and higher minute volume, and reduce alarms.


Assuntos
Desenho de Equipamento , Ventilação de Alta Frequência/instrumentação , Humanos , Recém-Nascido , Unidades de Terapia Intensiva Neonatal , Volume de Ventilação Pulmonar
19.
Arch Dis Child Fetal Neonatal Ed ; 96(2): F146-8, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-20584800

RESUMO

OBJECTIVE: To evaluate clinical practice of volume-targeted ventilation (VTV). DESIGN: Internet-based survey of all 50 tertiary neonatal units in Australia, New Zealand, Sweden, Denmark, Finland and Norway. RESULTS: Response rate was 100%. VTV was routinely used in 25 (50%) units; 15/25 (60%) in Australasia and 10/25 (40%) in the Nordic countries. The most common reason given for using VTV was that it reduces bronchopulmonary dysplasia (13/25; 52%). The median (IQR) of upper limits of target tidal volume were (1) for initial ventilation of preterm infants with respiratory distress syndrome 5.0 (4.6-6.0) ml/kg and (2) for infants with ventilator-dependent bronchopulmonary dysplasia 6.0 (5.0-8.0) ml/kg. The median (IQR) maximum peak inspiratory pressure limit units were prepared to use in VTV-mode was 35 (30-42.5) cm H(2)O. CONCLUSION: Half of the units used VTV routinely, but with a considerable variation in VTV practice. More studies are required to establish best VTV practice.


Assuntos
Terapia Intensiva Neonatal/métodos , Respiração Artificial/métodos , Peso ao Nascer , Pesquisas sobre Serviços de Saúde , Humanos , Recém-Nascido , Recém-Nascido Prematuro , Recém-Nascido de muito Baixo Peso , Internet , Prática Profissional/estatística & dados numéricos , Respiração Artificial/estatística & dados numéricos , Síndrome do Desconforto Respiratório do Recém-Nascido/terapia
20.
Cochrane Database Syst Rev ; (11): CD003666, 2010 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-21069677

RESUMO

BACKGROUND: Damage caused by lung overdistension (volutrauma) has been implicated in the development bronchopulmonary dysplasia (BPD). Modern neonatal ventilation modes can target a set tidal volume as an alternative to traditional pressure-limited ventilation using a fixed inflation pressure. Volume targeting aims to produce a more stable tidal volume in order to reduce lung damage and stabilise pCO(2) OBJECTIVES: To determine whether volume-targeted ventilation (VTV) compared with pressure-limited ventilation (PLV) leads to reduced rates of death and BPD in newborn infants. Secondary objectives were to determine whether use of VTV affected outcomes including air leak, cranial ultrasound findings and neurodevelopment. SEARCH STRATEGY: The search strategy comprised searches of the Cochrane Central Register of Controlled Trials, MEDLINE PubMed 1966 to January 2010, and hand searches of reference lists of relevant articles and conference proceedings. SELECTION CRITERIA: All randomised and quasi-randomised trials comparing the use of volume-targeted versus pressure-limited ventilation in infants of less than 28 days corrected age. DATA COLLECTION AND ANALYSIS: Two review authors assessed the methodological quality of eligible trials and extracted data independently. When appropriate, meta-analysis was conducted to provide a pooled estimate of effect. For categorical data the relative risk (RR) and risk difference (RD) were calculated with 95% confidence intervals. Number needed to treat was calculated when RD was statistically significant. Continuous data were analysed using weighted mean difference. MAIN RESULTS: Twelve randomised trials met our inclusion criteria; nine parallel trials (629 infants) and three crossover trials (64 infants).The use of VTV modes resulted in a reduction in the combined outcome of death or bronchopulmonary dysplasia [typical RR 0.73 (95% CI 0.57 to 0.93), NNT8 (95% CI 5 to 33)]. VTV modes also resulted in reductions in pneumothorax [typical RR 0.46 (95% CI 0.25 to 0.84), NNT 17 (95% CI 10 to 100)], days of ventilation [MD -2.36 (95% CI -3.9 to -0.8)], hypocarbia [typical RR 0.56 (95%CI 0.33 to 0.96), NNT 4 (95% CI 2 to 25)] and the combined outcome of periventricular leukomalacia or grade 3-4 intraventricular haemorrhage [typical RR 0.48 (95% CI 0.28 to 0.84), NNT 11 (95% CI 7 to 50)]. AUTHORS' CONCLUSIONS: Infants ventilated using VTV modes had reduced death and chronic lung disease compared with infants ventilated using PLV modes. Further studies are needed to identify whether VTV modes improve neurodevelopmental outcomes and to compare and refine VTV strategies.


Assuntos
Displasia Broncopulmonar/prevenção & controle , Ventilação com Pressão Positiva Intermitente/métodos , Displasia Broncopulmonar/etiologia , Humanos , Recém-Nascido , Recém-Nascido Prematuro , Ventilação com Pressão Positiva Intermitente/mortalidade , Ensaios Clínicos Controlados Aleatórios como Assunto
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA