Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

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Dynamics and stability of an iron drop falling in a magma ocean

International audienceThe latest stages of planetary accretion involved large impacts between differentiated bodies, hence large scale melting events. Consequently, the iron brought by the impactors sank within a deep magma ocean, before reaching the protocore. Yet the fluid dynamics of this process remains poorly known. Here, we report numerical simulations of the sinking dynamics of an initially spherical liquid iron drop within a molten silicate phase, up to its possible fragmentation. We consider a 2D cylindrical axisymmetric geometry. We vary the viscosity of the molten silicates in the range of 0.05 Pa.s to 100 Pa.s and the initial radius of the iron drop in the range of 1mm to 350 mm. Hence, we investigate Reynolds number in the range of [0.027-85600] and Weber number in the range of [0.073-18 7480]. Our numerical model constrains the morphology, dynamics and stability of the iron drop as a function of the dimensionless Weber and Reynolds numbers as well as of the viscosity ratio between the molten silicates and the liquid iron drop. In particular, we show that the maximal stable drop radius and the critical Weber number are monotonically increasing functions of the magma ocean viscosity. Increasing the Weber number decreases the boundary layer thickness at the drop boundary. The momentum boundary layer thickness depends mainly on the drop radius and slightly on the magma ocean viscosity. Increasing the viscosity of the silicate phase prevents oscillations of the iron phase and limits the exchange surface. Oppositely, increasing the initial radius of the iron drop enhances its deformation and increases its relative exchange surface. Above the critical Weber number, we confirm that the fragmentation of the liquid iron occurs within a falling distance equal to 3.5-8 times the drop initial radius in the explored range of moderate Weber number, and we describe a variety of fragmentation regimes. Consequences for Earth's formation models 33 are briefly assessed

Effect of H 2 O on metal–silicate partitioning of Ni, Co, V, Cr, Mn and Fe: Implications for the oxidation state of the Earth and Mars

International audienceThis study investigates the metal–silicate partitioning of Ni, Co, V, Cr, Mn and Fe during core mantle differentiation of terrestrial planets under hydrous conditions. For this, we equilibrated a molten hydrous CI chondrite model composition with various Fe-rich alloys in the system Fe–C–Ni–Co–Si–S in a multi-anvil over a range of P, T, fO2 and water content (5–20 GPa, 2073–2500 K, from 1 to 5 log units below the iron–wüstite (IW) buffer and for XH2O varying from 500 ppm to 1.5 wt%). By comparing the present experiments with the available data sets on dry systems, we observes that the effect of water on the partition coefficients of moderately siderophile elements is only moderate. For example, for iron we observed a decrease in the partition coefficient of Fe (Dmet/silFe) from 9.5 to 4.3, with increasing water content of the silicate melt, from 0 to 1.44 wt%, respectively. The evolution of metal–silicate partition coefficients of Ni, Co, V, Cr, Mn and Fe are modelled based on sets of empirical parameters. These empirical models are then used to refine the process of core segregation during accretion of Mars and the Earth. It appears that the likely presence of 3.5 wt% water on Mars during the core–mantle segregation could account for ∼74% of the FeO content of the Martian mantle. In contrast, water does not play such an important role for the Earth; only 4–6% of the FeO content of its mantle could be due to the water-induced Fe-oxidation, for a likely initial water concentration of 1.8 wt%. Thus, in order to reproduce the present-day FeO content of 8 wt% in the mantle, the Earth could initially have been accreted from a large fraction (between 85% and 90%) of reducing bodies (similar to EH chondrites), with 10–15% of the Earth’s mass likely made of more oxidized components that introduced the major part of water and FeO to the Earth. This high proportion of enstatite chondrites in the original constitution of the Earth is consistent with the 17O,48Ca,50Ti,62Ni and 90Mo isotopic study by Dauphas et al. (2014). If we assume that the CI-chondrite was oxidized during accretion, its intrinsically high water content suggests a maximum initial water concentration in the range of 1.2–1.8 wt% for the Earth, and 2.5–3.5 wt% for Mars

Dynamics of core-mantle separation: Influence of viscosity contrast and metal/silicate partition coefficients on the chemical equilibrium

International audienceThe composition of the Earth's core and mantle is set by the chemical equilibrium between metals and silicates during core/mantle segregation. The metallic core separated from the mantle by gravitational descent in the form of diapirs in a magma ocean, and therefore the dynamics of the diapir's downward movement has an influence on the chemical equilibrium. In this study, we characterize the descent of metallic droplets into a molten silicate using numerical models. By varying the silicate and metal viscosities (between 0.1 and 1000 Pa·s for each phase) as well as the partition coefficient between metal and silicate (Dmet/sil, varying between 1 and 1000), we obtained quantifying parametrizing equations for the degree of equilibrium between molten metal and molten silicate, in a regime characterized by low We (We < 10) and low Re (10−3 < Re<102). We showed that the main parameters controlling the equilibrium for a siderophile element are the viscosity of the silicate and the partition coefficient. We applied our parameterization for Ni and Co in the context of late accretion on Earth so as to quantify the variation of the Ni/Co ratio after a large impact as a function of the magma ocean viscosity, for an iron-rain scenario of metal/silicate segregation. Using previous models (Canup, 2004) of the Moon–forming impact, we showed that the Moon formation had an effect on the current Ni/Co ratio. Depending on the radius of Theia's core and the viscosity of the magma ocean produced after the impact between the proto-Earth and Theia, the Moon formation could account for 0.45% to 3% of the current Ni/Co ratio for magma ocean viscosities of 0.1 to 100 Pa·s, respectively

Uranium and thorium partitioning in the bulk silicate Earth and the oxygen content of Earth’s core

International audienceThis study investigates the partitioning of U and Th between molten metal and silicate liquid (DUandDTh) during Earth’score-mantle differentiation. We report new Th partition coefficients between chondritic silicate melt and various Fe-rich alloysin the system Fe-Ni-C-S-Si as determined by experiments in a multi-anvil apparatus at 3–8 GPa, 2073–2373 K, and oxygenfugacities from 1.5 to 5 log units below the iron-wu ̈stite (IW) buffer. By compiling all existing data on molten metal-silicateliquid partitioning of U and Th, we develop global models of U and Th partitioning between the mantle and core throughoutEarth’s accretion. The calculated concentrations in the Bulk Silicate Earth (BSE) are in agreement with previous studies(UBSE= 11.42 ± 0.45 ppb and ThBSE= 43.20 ± 1.73 ppb), whereas the contents of these radioactive elements in the Earth’score remain negligible. Compared to recent geochemical estimations, the calculated (Th/U)BSEsupports EL rather than EHenstatite chondrites as the reduced building blocks of the Earth. Furthermore, we demonstrate that Th is much more sensitivethan U to the oxygen content of the metallic phase. To reproduce the Th/U ratio of the BSE within its uncertainties, the oxy-gen content of the Earth’s core must be lower than 4.0 wt%. By combining other existing constraints, this suggests that thecore contains 2.0–4.0 wt% O. The calculations of U and Th concentrations and Th/U in the BSE developed herein can be usedas new constraints for determining the concentrations of other refractory lithophile elements in the BSE as soon as theirmetal-silicate partition coefficients are well constrained over the conditions of core segregation

Silicate melts during Earth's core formation

Co-auteur étrangerInternational audienceAccretion from primordial material and its subsequent differentiation into a planet with core and mantle are fundamental problems in terrestrial and solar system. Many of the questions about the processes, although well developed as model scenarios over the last few decades, are still open and much debated. In the early Earth, during its formation and differentiation into rocky mantle and iron-rich core, it is likely that silicate melts played an important part in shaping the Earth's main reservoirs as we know them today. Here, we review several recent results in a deep magma ocean scenario that give tight constraints on the early evolution of our planet. These results include the behaviour of some siderophile elements (Ni and Fe), lithophile elements (Nb and Ta) and one volatile element (Helium) during Earth's core formation. We will also discuss the melting and crystallization of an early magma ocean, and the implications on the general feature of core-mantle separation and the depth of the magma ocean. The incorporation of Fe2 + and Fe3 + in bridgmanite during magma ocean crystallization is also discussed. All the examples presented here highlight the importance of the prevailing conditions during the earliest time of Earth's history in determining the composition and dynamic history of our planet