Radiation-induced growth and isothermal decay of infrared-stimulated luminescence from feldspar

Optically stimulated luminescence (OSL) ages can determine a wide range of geological events or processes, such as the timing of sediment deposition, the exposure duration of a rock surface, or the cooling rate of bedrock. The accuracy of OSL dating critically depends on our capability to describe the growth and decay of laboratory-regenerated luminescence signals. Here we review a selection of common models describing the response of infrared stimulated luminescence (IRSL) of feldspar to constant radiation and temperature as administered in the laboratory. We use this opportunity to introduce a general-order kinetic model that successfully captures the behaviour of different materials and experimental conditions with a minimum of model parameters, and thus appears suitable for future application and validation in natural environments. Finally, we evaluate all the presented models by their ability to accurately describe a recently published feldspar multi-elevated temperature post-IR IRSL (MET-pIRIR) dataset, and highlight each model's strengths and shortfalls

Exploring IRSL 50 fading variability in bedrock feldspars and implications for OSL thermochronometry

International audienceOptically Stimulated Luminescence (OSL) is a well-established Quaternary dating method, which has recently been adapted to application in low-temperature thermochronometry. The Infra-Red Stimulated Luminescence (IRSL) of feldspar, which so far is the most promising target signal in thermochronometry, is unfortunately prone to anomalous fading. The fading of feldspar IRSL is at times not only challenging to measure, but also laborious to incorporate within luminescence growth models. Quantification of IRSL fading is therefore a crucial step in OSL thermochronometry, raising questions regarding (i) reproducibility and reliability of laboratory measurements of fading, as well as (ii) the applicability of existing fading models to quantitatively predict the level of IRSL field saturation in nature. Here we investigate the natural luminescence signal and anomalous fading of IRSL measured at 50 °C (IRSL50) in 32 bedrock samples collected from a variety of lithologies and exhumation settings (Alaska and Norway). We report a large span of IRSL50 fading rates between samples (g2days ranging from ∼0.5 to ∼45%/decade), which further demonstrates (i) a good reproducibility between two common fading measurement protocols, and (ii) the ability of tunnelling models to predict the level of feldspar IRSL50 field saturation in nature. We observe higher IRSL50 fading in feldspar with increasing Ca content, although other factors cannot be dismissed at present. Finally, our dataset confirms that the applicability of feldspar IRSL50 in OSL thermochronometry is limited to rapidly-exhuming settings or warm subsurface environments

PICU mortality of children with cancer admitted to pediatric intensive care unit : a systematic review and meta-analysis

Background: Outcomes for children diagnosed with cancer have improved dramatically over the past 20 years. However, although 40% of pediatric cancer patients require at least one intensive care admission throughout their disease course, PICU outcomes and resource utilization by this population have not been rigorously studied in this specific group. Methods: Using a systematic strategy, we searched Medline, Embase, and CINAHL databases for articles describing PICU mortality of pediatric cancer patients admitted to PICU. Two investigators independently applied eligibility criteria, assessed data quality, and extracted data. We pooled PICU mortality estimates using random-effects models and examined mortality trends over time using meta-regression models. Results: Out of 1218 identified manuscripts, 31 studies were included covering 16,853 PICU admissions with the majority being retrospective in nature. Overall pooled weighted mortality was 27.8% (95% confidence interval (CI), 23.7-31.9%). Mortality decreased slightly over time when post-operative patients were excluded. The use of mechanical ventilation (odds ratio (OR): 18.49 [95% CI 13.79-24.78], p < 0.001), inotropic support (OR: 14.05 [95% CI 9.16-21.57], p < 0.001), or continuous renal replacement therapy (OR: 3.24 [95% CI 1.31-8.04], p = 0.01) was significantly associated with PICU mortality. Conclusions: PICU mortality rates of pediatric cancer patients are far higher when compared to current mortality rates of the general PICU population. PICU mortality has remained relatively unchanged over the past decades, a slight decrease was only seen when post-operative patients were excluded. This compared infavorably with the improved mortality seen in adults with cancer admitted to ICU, where research-led improvements have led to the paradigm of unlimited, aggressive ICU management without any limitations on resuscitations status, for a time-limited trial

Can they stomach it? Parent and practitioner acceptability of a trial comparing gastric residual volume measurement versus no gastric residual volume in UK NNU and PICUs: a feasibility study.

BACKGROUND: Routine measurement of gastric residual volume (GRV) to guide feeding in neonatal and paediatric intensive care is widespread. However, this practice is not evidence based and may cause harm. As part of a feasibility study, we explored parent and practitioner views on the acceptability of a trial comparing GRV measurement or no GRV measurement. METHODS: A mixed-methods study involving interviews and focus groups with practitioners and interviews with parents with experience of tube feeding in neonatal and/or paediatric intensive care. A voting system recorded closed question responses during practitioner data collection, enabling the collection of quantitative and qualitative data. Data were analysed using thematic analysis and descriptive statistics. RESULTS: We interviewed 31 parents and nine practitioners and ran five practitioner focus groups (n=42). Participants described how the research question was logical, and the intervention would not be invasive and potential benefits of not withholding the child's feeds. However, both groups held concerns about the potential risk of not measuring GRV, including delayed diagnosis of infection and gut problems, increased risk of vomiting into lungs and causing discomfort or pain. Parent's views on GRV measurement and consent decision making were influenced by their views on the importance of feeding in the ICU, their child's prognosis and associated comorbidities or complications. CONCLUSIONS: The majority of parents and practitioners viewed the proposed trial as acceptable. Potential concerns and preferences were identified that will need careful consideration to inform the development of the proposed trial protocol and staff training

Enhance quality care performance: Determination of the variables for establishing a common database in French paediatric critical care units

Abstract Selected variables for the French Paediatric Intensive Care registry. Rationale, aims, and objectives Providing quality care requires follow-up in regard to clinical and economic activities. Over the past decade, medical databases and patient registries have expanded considerably, particularly in paediatric critical care medicine (eg, the Paediatric Intensive Care Audit Network (PICANet) in the UK, the Australian and New Zealand Paediatric Intensive Care (ANZPIC) Registry in Australia and New Zealand, and the Virtual Paediatric Intensive Care Unit Performance System (VPS) in the USA). Such a registry is not yet available in France. The aim of this study was to determine variables that ought to be included in a French paediatric critical care registry. Methods Variables, items, and subitems from 3 foreign registries and 2 French local databases were used. Items described each variable, and subitems described items. The Delphi method was used to evaluate and rate 65 variables, 90 items, and 17 subitems taking into account importance or relevance based on input from 28 French physicians affiliated with the French Paediatric Critical Care Group. Two ratings were used between January and May 2013. Results Fifteen files from 10 paediatric intensive care units were included. Out of 65 potential variables, 48 (74%) were considered to be indispensable, 16 (25%) were considered to be optional, and 1 (2%) was considered to be irrelevant. Out of 90 potential items, 62 (69%) were considered to be relevant, 23 (26%) were considered to be of little relevance, and 5 (6%) were considered to be irrelevant. Out of 17 potential subitems, 9 (53%) were considered to be relevant, 6 (35%) were considered to be of little relevance, and 2 (12%) were considered to be irrelevant. Conclusions The necessary variables that ought to be included in a French paediatric critical care registry were identified. The challenge now is to develop the French registry for paediatric intensive care units

OSL-thermochronometry of feldspar from the KTB borehole, Germany

The reconstruction of thermal histories of rocks (thermochronometry) is a fundamental tool both in Earth science and in geological exploration. However, few methods are currently capable of resolving the low-temperature thermal evolution of the upper ∼2 km of the Earth's crust. Here we introduce a new thermochronometer based on the infrared stimulated luminescence (IRSL) from feldspar, and validate the extrapolation of its response to artificial radiation and heat in the laboratory to natural environmental conditions. Specifically, we present a new detailed Na-feldspar IRSL thermochronology from a well-documented thermally-stable crustal environment at the German Continental Deep Drilling Program (KTB). There, the natural luminescence of Na-feldspar extracted from twelve borehole samples (0.1–2.3 km depth, corresponding to 10–70 °C) can be either (i) predicted within uncertainties from the current geothermal gradient, or (ii) inverted into a geothermal palaeogradient of 29±2 °C km−1, integrating natural thermal conditions over the last ∼65 ka. The demonstrated ability to invert a depth–luminescence dataset into a meaningful geothermal palaeogradient opens new venues for reconstructing recent ambient temperatures of the shallow crust (200 °C Ma−1 range). Although Na-feldspar IRSL is prone to field saturation in colder or slower environments, the method's primary relevance appears to be for borehole and tunnel studies, where it may offer remarkably recent (<0.3 Ma) information on the thermal structure and history of hydrothermal fields, nuclear waste repositories and hydrocarbon reservoirs

Routine gastric residual volume measurement and energy target achievement in the PICU: A comparison study

Critically ill children frequently fail to achieve adequate energy intake and some care practices, such as the measurement of gastric residual volume (GRV) may contribute to this problem. We compared outcomes in two similar European Pediatric Intensive Care Units (PICUs): one which routinely measures GRV (PICU-GRV) to one unit that does not (PICU-noGRV). An observational pilot comparison study was undertaken. 87 children were included in the study, 42 (PICU-GRV) and 45 (PICU-noGRV). There were no significant differences in the percentage of energy targets achieved in the first four days of PICU admission although PICU-noGRV showed more consistent delivery of median (and IQR) energy targets, and less under and over feeding for PICU-GRV and PICU-noGRV Day 1 37 (14-72) vs 44 (0-100); Day 2 97 (53-126) vs 100 (100-100), Day 3 84 (45-112) vs 100 (100-100) , Day 4 101 (63-124) vs 100 (100-100). The incidence of vomiting was higher in PICU-GRV. No necrotising enterocolitis was confirmed in either unit and ventilator acquired pneumonia rates were not significantly different (7.01 vs 12 5.31 per 1000 ventilator days; p=0.70) between PICU-GRV and PICU-noGRV units. Conclusions: The practice of routine gastric residual measurement did not significantly impair energy targets in the first four days of PICU admission. However, not measuring GRV did not increase vomiting, ventilator acquired pneumonia or necrotising enterocolitis, which is the main reason clinicians cite for measuring GRV. What is known?•The practice of routinely measuring gastric residual volume is widespread in critical care units•This practice is increasingly being questioned in critically ill patients, both as a practice that increases •the likelihood of delivering inadequate enteral nutrition amounts and as a tool to assess feeding tolerance What is new? •Not routinely measuring gastric residual volume did not increase adverse events of ventilator acquired pneumonia, necrotising enterocolitis or vomiting •In the first four days of PICU stay, energy target achievement was not significantly different, but the rates of under and over feeding were higher in the routine GRV measurement uni

Holistic nutritional assessment in critically ill children

La malnutrition à l’admission en réanimation pédiatrique est fréquente et associée à une augmentation de la morbi-mortalité. Néanmoins, la plupart des études, limitées à une évaluation statique du statut nutritionnel, ne permettent pas une analyse fine de l’impact de la malnutrition. Une approche systémique associerait en plus d’une évaluation nutritionnelle statique, une analyse dynamique dans le temps, une analyse de la composition corporelle et une analyse physiopathologique et étiologique. Cette approche globale a été appliquée dans 4 études prospectives observationnelles, incluant des enfants sévèrement agressés de plus de 36 semaines d’âge corrigé. Il en ressort que la dénutrition globale à l’admission est fréquente (23,7%) et que la cassure des courbes de croissance avant l’admission est associée à une augmentation de la durée de séjour de 3 jours. L’enfant sévèrement agressé présente à l’admission des taux plasmatiques abaissés de 6 micronutriments impliqués dans le stress oxydant (Sélénium, Zinc, Cuivre, Vitamines C, E et bêta-carotène), proportionnellement au nombre de défaillances d’organe. La dénutrition globale et la fonte musculaire acquises en cours de séjour sont des phénomènes fréquents, précoces et importants, associés à une durée de séjour prolongée. Les changements métaboliques liés à l’agression sévère conduisent à une dénutrition. Ces processus adaptatifs sont parfois dépassés et la dénutrition pourra à son tour aggraver le pronostic. La bonne compréhension de la physiopathologie sous-jacente et un suivi systémique et systématique du statut nutritionnel sont les éléments indispensables à l’évaluation des stratégies nutritionnellesMalnutrition at pediatric Intensive care unit (PICU) admission is frequent and associated with impaired outcomes. However, most studies have focused solely on a static definition. A holistic approach would improve the description of malnutrition: this would include both a static and dynamic assessment of nutritional status, together with body composition assessment and with malnutrition classified based on its patho-physiology and etiology. This holistic assessment of malnutrition has been applied and examined in four observational studies which included critically ill children older than 36 gestational weeks (corrected age). These found that malnutrition was frequent at PICU admission (27.3%) and faltering growth prior to PICU admission was associated with an increased length of PICU stay (+3 days). Critically ill children present at admission with decreased plasma levels of 6 micro-nutrients (Selenium, Copper, Zinc, Vitamin C, E and beta-carotene) involved in anti-oxidative stress pathways. Nutritional status deterioration during PICU stay, and associated muscle mass loss occurred frequently and were intense. This early phenomenon was associated with extended length of PICU stay. A profound critical illness related metabolic shift leads to malnutrition as an adaptive process. However, malnutrition may also negatively impact on outcomes in this setting. These studies have led to a clearer understanding of the underlying patho-physiology. This, combined with a more systematic and holistic nutritional assessment, will enable implementation and assessment of nutritional strategies aiming to improve the functional outcome of critically ill childre

Évaluation nutritionnelle systémique de l’enfant en réanimation pédiatrique

Malnutrition at pediatric Intensive care unit (PICU) admission is frequent and associated with impaired outcomes. However, most studies have focused solely on a static definition. A holistic approach would improve the description of malnutrition: this would include both a static and dynamic assessment of nutritional status, together with body composition assessment and with malnutrition classified based on its patho-physiology and etiology. This holistic assessment of malnutrition has been applied and examined in four observational studies which included critically ill children older than 36 gestational weeks (corrected age). These found that malnutrition was frequent at PICU admission (27.3%) and faltering growth prior to PICU admission was associated with an increased length of PICU stay (+3 days). Critically ill children present at admission with decreased plasma levels of 6 micro-nutrients (Selenium, Copper, Zinc, Vitamin C, E and beta-carotene) involved in anti-oxidative stress pathways. Nutritional status deterioration during PICU stay, and associated muscle mass loss occurred frequently and were intense. This early phenomenon was associated with extended length of PICU stay. A profound critical illness related metabolic shift leads to malnutrition as an adaptive process. However, malnutrition may also negatively impact on outcomes in this setting. These studies have led to a clearer understanding of the underlying patho-physiology. This, combined with a more systematic and holistic nutritional assessment, will enable implementation and assessment of nutritional strategies aiming to improve the functional outcome of critically ill childrenLa malnutrition à l’admission en réanimation pédiatrique est fréquente et associée à une augmentation de la morbi-mortalité. Néanmoins, la plupart des études, limitées à une évaluation statique du statut nutritionnel, ne permettent pas une analyse fine de l’impact de la malnutrition. Une approche systémique associerait en plus d’une évaluation nutritionnelle statique, une analyse dynamique dans le temps, une analyse de la composition corporelle et une analyse physiopathologique et étiologique. Cette approche globale a été appliquée dans 4 études prospectives observationnelles, incluant des enfants sévèrement agressés de plus de 36 semaines d’âge corrigé. Il en ressort que la dénutrition globale à l’admission est fréquente (23,7%) et que la cassure des courbes de croissance avant l’admission est associée à une augmentation de la durée de séjour de 3 jours. L’enfant sévèrement agressé présente à l’admission des taux plasmatiques abaissés de 6 micronutriments impliqués dans le stress oxydant (Sélénium, Zinc, Cuivre, Vitamines C, E et bêta-carotène), proportionnellement au nombre de défaillances d’organe. La dénutrition globale et la fonte musculaire acquises en cours de séjour sont des phénomènes fréquents, précoces et importants, associés à une durée de séjour prolongée. Les changements métaboliques liés à l’agression sévère conduisent à une dénutrition. Ces processus adaptatifs sont parfois dépassés et la dénutrition pourra à son tour aggraver le pronostic. La bonne compréhension de la physiopathologie sous-jacente et un suivi systémique et systématique du statut nutritionnel sont les éléments indispensables à l’évaluation des stratégies nutritionnelle

Nutrition parentérale pédiatrique (évaluation des pratiques professionnelles au groupement hospitalier est de Lyon)

L'amélioration de l'état nutritionnel de la population constitue, en ce début de 21ème siècle, un enjeu majeur pour les politiques de santé publique. La dénutrition hospitalière, à l'origine de conséquences délétères pour le patient, soulève la question du bon usage de la nutrition artificielle. L'objectif de ce travail était d'effectuer un état des lieux de la pratique de nutrition parentérale à la carte en population pédiatrique, en vue d'en améliorer la qualité. L'évaluation des pratiques professionnelles a été réalisée sous la forme d'un audit clinique. Afin d'analyser la qualité de la prise en charge nutritionnelle, nous avons axé cette étude sur l'évaluation de trois paramètres: la pertinence de l'indication, la qualité de la prescription et la rigueur de la surveillance. L'ensemble des patients ayant bénéficié d'une nutrition parentérale à la carte au cours de l'année 2012 a été examiné. . Quarante-deux patients ont été inclus correspondant au total à l'analyse de 308 prescriptions. Au terme de ce travail, il apparaît qu'un suivi rigoureux des recommandations soit réalisé concernant l'indication de la nutrition parentérale. En revanche, les résultats démontrent aussi une insuffisance du suivi des recommandations portant sur la prescription et la surveillance. Afin d'optimiser la prise en charge nutritionnelle, ces deux points doivent fait l'objet d'actions d'amélioration. A cet effet, un questionnaire d'évaluation des connaissances des prescripteurs a été réalisé sous l'égide du CLAN. D'autres axes d'amélioration sont en cours de développement avec notamment la réalisation d'un logiciel d'aide à la prescription et la mise à disposition facilitée de documents d'informations concernant la prise en charge globale du soin nutritionnelLYON1-BU Santé (693882101) / SudocSudocFranceF