This document represents the first collaboration between 2 organizations-the American Society for Parenteral and Enteral Nutrition and the Society of Critical Care Medicine-to describe best practices in nutrition therapy in critically ill children. The target of these guidelines is intended to be the pediatric critically ill patient (>1 month and 2-3 days in a PICU admitting medical, surgical, and cardiac patients. In total, 2032 citations were scanned for relevance. The PubMed/MEDLINE search resulted in 960 citations for clinical trials and 925 citations for cohort studies. The EMBASE search for clinical trials culled 1661 citations. In total, the search for clinical trials yielded 1107 citations, whereas the cohort search yielded 925. After careful review, 16 randomized controlled trials and 37 cohort studies appeared to answer 1 of the 8 preidentified question groups for this guideline. We used the GRADE criteria (Grading of Recommendations, Assessment, Development, and Evaluation) to adjust the evidence grade based on assessment of the quality of study design and execution. These guidelines are not intended for neonates or adult patients. The guidelines reiterate the importance of nutrition assessment-particularly, the detection of malnourished patients who are most vulnerable and therefore may benefit from timely intervention. There is a need for renewed focus on accurate estimation of energy needs and attention to optimizing protein intake. Indirect calorimetry, where feasible, and cautious use of estimating equations and increased surveillance for unintended caloric underfeeding and overfeeding are recommended. Optimal protein intake and its correlation with clinical outcomes are areas of great interest. The optimal route and timing of nutrient delivery are areas of intense debate and investigations. Enteral nutrition remains the preferred route for nutrient delivery. Several strategies to optimize enteral nutrition during critical illness have emerged. The role of supplemental parenteral nutrition has been highlighted, and a delayed approach appears to be beneficial. Immunonutrition cannot be currently recommended. Overall, the pediatric critical care population is heterogeneous, and a nuanced approach to individualizing nutrition support with the aim of improving clinical outcomes is necessary.

Guidelines for the Provision and Assessment of Nutrition Support Therapy in the Adult Critically Ill Patient Society of Critical Care Medicine (SCCM) and American Society for Parenteral and Enteral Nutrition (A.S.P.E.N.)

A.S.P.E.N. and SCCM are both nonprofit organizations composed of multidisciplinary healthcare professionals. The mission of A.S.P.E.N. is to improve patient care by advancing the science and practice of clinical nutrition and metabolism. The mission of SCCM is to secure the highest quality care for all critically ill and injured patients. Guideline Limitations: These A.S.P.E.N.−SCCM Clinical Guidelines are based on general conclusions of health professionals who, in developing such guidelines, have balanced potential benefits to be derived from a particular mode of medical therapy against certain risks inherent with such therapy. However, practice guidelines are not intended as absolute requirements. The use of these practice guidelines does not in any way project or guarantee any specific benefit in outcome or survival. The judgment of the healthcare professional based on individual circumstances of the patient must always take precedence over the recommendations in these guidelines. The guidelines offer basic recommendations that are supported by review and analysis of the current literature, other national and international guidelines, and a blend of expert opinion and clinical practicality. The population of critically ill patients in an intensive care unit (ICU) is not homogeneous. Many of the studies on which the guidelines are based are limited by sample size, patient heterogeneity, variability in disease severity, lack of baseline nutritional status, and insufficient statistical power for analysis. Periodic Guideline Review and Update: This particular report is an update and expansion of guidelines published by A.S.P.E.N. and SCCM in 2009 (1). Governing bodies of both A.S.P.E.N. and SCCM have mandated that these guidelines be updated every three to five years. The database of randomized controlled trials (RCTs) that served as the platform for the analysis of the literature was assembled in a joint “harmonization process” with the Canadian Clinical Guidelines group. Once completed, each group operated separately in their interpretation of the studies and derivation of guideline recommendations (2). The current A.S.P.E.N. and SCCM guidelines included in this paper were derived from data obtained via literature searches by the authors through December 31, 2013. Although the committee was aware of landmark studies published after this date, these data were not included in this manuscript. The process by which the literature was evaluated necessitated a common end date for the search review. Adding a last-minute landmark trial would have introduced bias unless a formalized literature search was re-conducted for all sections of the manuscript. Target Patient Population for Guideline: The target of these guidelines is intended to be the adult (≥ 18 years) critically ill patient expected to require a length of stay (LOS) greater than 2 or 3 days in a medical ICU (MICU) or surgical ICU (SICU). The current guidelines were expanded to include a number of additional subsets of patients who met the above criteria, but were not included in the previous 2009 guidelines. Specific patient populations addressed by these expanded and updated guidelines include organ failure (pulmonary, renal, and liver), acute pancreatitis, surgical subsets (trauma, traumatic brain injury [TBI], open abdomen [OA], and burns), sepsis, postoperative major surgery, chronic critically ill, and critically ill obese. These guidelines are directed toward generalized patient populations but, like any other management strategy in the ICU, nutrition therapy should be tailored to the individual patient. Target Audience: The intended use of these guidelines is for all healthcare providers involved in nutrition therapy of the critically ill, primarily physicians, nurses, dietitians, and pharmacists. Methodology: The authors compiled clinical questions reflecting key management issues in nutrition therapy. A committee of multidisciplinary experts in clinical nutrition composed of physicians, nurses, pharmacists, and dietitians was jointly convened by the two societies.

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Guidelines for the Provision and Assessment of Nutrition Support Therapy in the Adult Critically Ill Patient: Society of Critical Care Medicine (SCCM) and American Society for Parenteral and Enteral Nutrition (A.S.P.E.N.).

Guidelines for the Provision and Assessment of Nutrition Support Therapy in the Adult Critically Ill Patient

Understanding the formation of stars in galaxies is central to much of modern astrophysics. However, a quantitative prediction of the star formation rate and the initial distribution of stellar masses remains elusive. For several decades it has been thought that the star formation process is primarily controlled by the interplay between gravity and magnetostatic support, modulated by neutral-ion drift (known as ambipolar diffusion in astrophysics). Recently, however, both observational and numerical work has begun to suggest that supersonic turbulent flows rather than static magnetic fields control star formation. To some extent, this represents a return to ideas popular before the importance of magnetic fields to the interstellar gas was fully appreciated. This review gives a historical overview of the successes and problems of both the classical dynamical theory and the standard theory of magnetostatic support, from both observational and theoretical perspectives. The outline of a new theory relying on control by driven supersonic turbulence is then presented. Numerical models demonstrate that, although supersonic turbulence can provide global support, it nevertheless produces density enhancements that allow local collapse. Inefficient, isolated star formation is a hallmark of turbulent support, while efficient, clustered star formation occurs in its absence. The consequences of this theory are then explored for both local star formation and galactic-scale star formation. It suggests that individual star-forming cores are likely not quasistatic objects, but dynamically collapsing. Accretion onto these objects varies depending on the properties of the surrounding turbulent flow; numerical models agree with observations showing decreasing rates. The initial mass distribution of stars may also be determined by the turbulent flow. Molecular clouds appear to be transient objects forming and dissolving in the larger-scale turbulent flow, or else quickly collapsing into regions of violent star formation. Global star formation in galaxies appears to be controlled by the same balance between gravity and turbulence as small-scale star formation, although modulated by cooling and differential rotation. The dominant driving mechanism in star-forming regions of galaxies appears to be supernovae, while elsewhere coupling of rotation to the gas through magnetic fields or gravity may be important.

Control of star formation by supersonic turbulence

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Control of Star Formation by Supersonic Turbulence

The propagation of a shock wave into an interstellar medium is investigated by two-dimensional numerical hydrodynamic calculation with cooling, heating, and thermal conduction. We present results of the high-resolution, two-dimensional calculations to follow the fragmentation that results from thermal instability in a shock-compressed layer. We find that the geometrically thin cooling layer behind the shock front fragments into small cloudlets. The cloudlets have supersonic velocity dispersion in the warm neutral medium, in which the fragments are embedded as cold condensations. The fragments tend to coalesce and become larger clouds.

https://iopscience.iop.org/article/10.1086/338978/pdf

An Origin of Supersonic Motions in Interstellar Clouds

We investigate the propagation of a shock wave into a warm neutral medium and a cold neutral medium by one-dimensional hydrodynamic calculations with detailed treatment of thermal and chemical processes. Our main result shows that thermal instability inside the shock-compressed layer produces a geometrically thin, dense layer in which a large amount of hydrogen molecules are formed. Linear stability analysis suggests that this thermally collapsed layer will fragment into small molecular cloudlets. We expect that frequent compression due to supernova explosions, stellar winds, spiral density waves, etc., in the Galaxy causes the interstellar medium to be occupied by these small molecular cloudlets.

https://iopscience.iop.org/article/10.1086/308594/pdf

Molecular Cloud Formation in Shock-compressed Layers

Myo-inositol-1-phosphate (I[1]P) synthase (EC 5.5.1.4) catalyzes the reaction from glucose 6-phosphate to I(1)P, the first step of myo-inositol biosynthesis. Among the metabolites of I(1)P is inositol hexakisphosphate, which forms a mixed salt called phytin or phytate, a storage form of phosphate and cations in seeds. We have isolated a rice (Oryza sativa L.) cDNA clone, pRINO1, that is highly homologous to the I(1)P synthase from yeast and plants. Northern analysis of total RNA showed that the transcript accumulated to high levels in embryos but was undetectable in shoots, roots, and flowers. In situ hybridization of developing seeds showed that the transcript first appeared in the apical region of globular-stage embryos 2 d after anthesis (DAA). Strong signals were detected in the scutellum and aleurone layer after 4 DAA. The level of the transcript in these cells increased until 7 DAA, after which time it gradually decreased. Phytin-containing particles called globoids appeared 4 DAA in the scutellum and aleurone layer, coinciding with the localization of the RINO1 transcript. The temporal and spatial patterns of accumulation of the RINO1 transcript and globoids suggest that I(1)P synthase directs phytin biosynthesis in rice seeds.

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Temporal and Spatial Patterns of Accumulation of the Transcript of Myo-Inositol-1-Phosphate Synthase and Phytin-Containing Particles during Seed Development in Rice

We present the dynamics of a thermally bistable medium using one-dimensional numerical calculations, including cooling, heating, thermal conduction, and physical viscosity.We set up a two-phase medium from a thermally unstable one-phase medium and follow its long-term evolution. To clarify the role of thermal conduction, we compare the results of the two models, with and without thermal conduction. The calculations show that the thermal conduction helps to generate the kinetic energy of translational motions of the clouds. Next, we focus on spatial resolution because we have to resolve the Field length $\lambda_{\rm F}$, which is the characteristic length scale of the thermal conduction. The results show convergence only when thermal conduction is included and a large enough cell number is used. We find it necessary to maintain a cell size of less than $\lambda_{\rm F}/3$ to achieve a converged motion in the two-phase medium. We refer to the constraint that $\lambda_{\rm F}/3$ be resolved as the ``Field condition''. The inclusion of thermal conduction to satisfy the Field condition is crucial to numerical studies of thermal instability (TI) and may be important for studies of the turbulent interstellar two-phase medium: the calculations of TI without thermal conduction may be susceptible to contamination by artificial phenomena that do not converge with increasing resolutions.

The Field Condition: A New Constraint of Spatial Resolution in Simulations of the nonlinear Development of Thermal Instability

We present the dynamics of a thermally bistable medium using one-dimensional numerical calculations, including cooling, heating, thermal conduction, and physical viscosity. We set up a two-phase medium from a thermally unstable one-phase medium and follow its long-term evolution. To clarify the role of thermal conduction, we compare the results of the two models, with and without thermal conduction. The calculations show that the thermal conduction helps to generate the kinetic energy of translational motions of the clouds. Next, we focus on spatial resolution because we have to resolve the Field length λF, which is the characteristic length scale of the thermal conduction. The results show convergence only when thermal conduction is included and a large enough cell number is used. We find it necessary to maintain a cell size of less than λF/3 to achieve a converged motion in the two-phase medium. We refer to the constraint that λF/3 be resolved as the "Field condition." The inclusion of thermal conduction to satisfy the Field condition is crucial to numerical studies of thermal instability (TI) and may be important for studies of the turbulent interstellar two-phase medium: the calculations of TI without thermal conduction may be susceptible to contamination by artificial phenomena that do not converge with increasing resolutions.

Hiroshi Koyama

Papers

An Origin of Supersonic Motions in Interstellar Clouds

Molecular Cloud Formation in Shock-compressed Layers

Temporal and Spatial Patterns of Accumulation of the Transcript of Myo-Inositol-1-Phosphate Synthase and Phytin-Containing Particles during Seed Development in Rice

The Field Condition: A New Constraint of Spatial Resolution in Simulations of the nonlinear Development of Thermal Instability

The Field Condition: A New Constraint on Spatial Resolution in Simulations of the Nonlinear Development of Thermal Instability