Large Eddy Simulation of Unstably Stratified Turbulent Flow over Urban-Like Building Arrays

Thermal instability induced by solar radiation is the most common condition of urban atmosphere in daytime. Compared to researches under neutral conditions, only a few numerical works studied the unstable urban boundary layer and the effect of buoyancy force is unclear. In this paper, unstably stratified turbulent boundary layer flow over three-dimensional urban-like building arrays with ground heating is simulated. Large eddy simulation is applied to capture main turbulence structures and the effect of buoyancy force on turbulence can be investigated. Lagrangian dynamic subgrid scale model is used for complex flow together with a wall function, taking into account the large pressure gradient near buildings. The numerical model and method are verified with the results measured in wind tunnel experiment. The simulated results satisfy well with the experiment in mean velocity and temperature, as well as turbulent intensities. Mean flow structure inside canopy layer varies with thermal instability, while no large secondary vortex is observed. Turbulent intensities are enhanced, as buoyancy force contributes to the production of turbulent kinetic energy

Relationship between Doppler ultrasound parameters of uterine artery, umbilical artery, middle cerebral artery and placental vasculopathology and pregnancy outcome in preeclampsia rat model

Objective·To measure the parameters of the uterine artery, umbilical artery and middle cerebral artery in a rat model of preeclampsia (PE) by Doppler ultrasound, and compare the pathological changes in placental blood vessels and pregnancy outcomes, in order to provide an effective method and reference for evaluating placental function in PE animal models.Methods·PE (n=8) and normal pregnancy (NP, n=8) groups in Sprague-Dawley (SD) rat models were established by intraperitoneal injections of N′-nitro-L-arginine methylesterhydrochloride (L-NAME) and 0.9% sodium chloride solution. Blood pressure and proteinuria indexes were detected to evaluate whether the model was successfully established. On gestational day 19 (GD19), Doppler ultrasound was utilized to measure the parameters of the uterine artery, umbilical artery and the fetal middle cerebral artery in both the PE and NP groups. After termination of the pregnancies, placental function was evaluated through the pathology of placental blood vessels and the quality of the fetuses and placentas.Results·In the PE group, both blood pressure (GD15: P=0.001; GD19: P=0.001) and proteinuria (GD15: P=0.001; GD19: P=0.001) were significantly higher than those in the NP group. The pulsatility index (PI) of the umbilical artery and uterine artery was notably elevated in the PE group compared to the NP group (both P=0.000). Furthermore, the resistance index (RI) of the fetal middle cerebral artery was significantly lower than that in the PE group (P=0.000). While the number of fetal rats did not differ significantly, the quality of placental and fetal rats was notably lower in the PE group (P=0.006 and P=0.000, respectively). Immunohistochemical staining of placental tissue revealed that the number of placental micro vessel densities in the PE group was less than that in the NP group (P=0.001). Correlation analysis revealed that placental micro vessel density, fetal quality and placental quality were inversely related with the RI of the umbilical artery and the PI and RI of the uterine artery, and positively correlated with the S/D, PI and RI of the fetal middle cerebral artery (all P<0.05). Conculsion·Doppler ultrasound assessment of the uterine artery, umbilical artery and middle cerebral artery indices in L-NAME-induced PE rat models effectively reflects pregnancy outcomes and placental vascular pathology. This method is valuable for evaluating placental vascular perfusion in PE rat models, offering practicality and convenience for research involving animal models

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

Abstract: 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

The original version of this article unfortunately contained a mistake