Relative impact of red blood cell transfusion and anaemia on 5-year mortality in cardiac surgery

OBJECTIVESThe aim was to compare the relative effects of red blood cell (RBC) transfusion and preoperative anaemia on 5-year mortality following open-heart cardiac surgery using structural equation modelling. We hypothesized that patient risk factors associated with RBC transfusion are of larger importance than transfusion itself.Open in a separate windowMETHODSThis prospective cohort study, part of the Cardiac Surgery Outcome Study at St. Olavs University Hospital, Trondheim, Norway, included open-heart on-pump cardiac surgery patients operated on from 2000 through 2017 (n = 9315). Structural equation modelling, which allows for intervariable correlations, was used to analyse pathway diagrams between known risk factors and observed mortality between 30 days and 5 years postoperatively. Observation times between 30 days and 1 year, and 1–5 years postoperatively were also compared with the main analysis.RESULTSIn a simplified model, preoperative anaemia had a larger effect on 5-year mortality than RBC transfusion (standardized coefficients: 0.17 vs 0.09). The complete model including multiple risk factors showed that patient risk factors such as age (0.15), anaemia (0.10), pulmonary disease (0.11) and higher creatinine level (0.12) had larger effects than transfusion (0.03). Results from several sensitivity analyses supported the main findings. The models showed good fit.CONCLUSIONSPreoperative anaemia had a larger impact on 5-year mortality than RBC transfusion. Differences in 5-year mortality were mainly associated with patient risk factors.     

Hospital nursing organizational factors,nursing care left undone,and nurse burnout as predictors of patient safety: A structural equation modeling analysis

BackgroundPromotion of patient safety is among the most important goals and challenges of healthcare systems worldwide in countries including China. Donabedian’s Structure-Process-Outcome model implies that patient safety is affected by hospital nursing organizational factors and nursing care process. However, studies are imperative for a clear understanding about the mechanisms by which patient safety is affected to guide practice.ObjectiveThe objective of this study was to explore the impact of hospital nursing work environment, workload, nursing care left undone, and nurse burnout on patient safety.DesignThis was a cross-sectional study conducted in 23 hospitals in Guangdong province, China in 2014. Data from nurses (n = 1542) responsible for direct care on 111 randomly sampled medical and surgical units were analyzed.MethodsWork environment was measured by the Practice Environment Scale of Nursing Work Index. Workload was measured by day shift unit patient-nurse ratio and non-professional tasks conducted by nurses. Nursing care left undone was measured by 12 items addressing necessary nursing activities. Nurse burnout was measured by the emotional exhaustion subscale of the Maslach Burnout Inventory-Human Services Survey. Patient safety was measured by three items indicating nurses’ perception of overall patient safety and nine items addressing patient adverse events. Structural equation modeling was used to examine a hypothesized model that supposed work environment and workload have both direct and indirect effects on patient safety through nursing care left undone and nurse burnout.ResultsThe findings generally supported the hypothesized model. Better work environment was associated with better patient safety both directly and indirectly. Lower workload primarily indirectly related to better patient safety. Nursing care left undone and nurse burnout were mediators negatively associated with patient safety.ConclusionsImproving work environment, increasing nurse staffing levels, and providing sufficient support for nurses to spend more time on direct patient care would be beneficial to patient safety improvement.     

Characterization of creatine guanidinium proton exchange by water‐exchange (WEX) spectroscopy for absolute‐pH CEST imaging in vitro

Chemical exchange saturation transfer (CEST) enables indirect detection of small metabolites in tissue by MR imaging. To optimize and interpret creatine‐CEST imaging we characterized the dependence of the exchange‐rate constant k_sw of creatine guanidinium protons in aqueous creatine solutions as a function of pH and temperature T in vitro. Model solutions in the low pH range (pH = 5–6.4) were measured by means of water‐exchange (WEX)‐filtered ¹H NMR spectroscopy on a 3 T whole‐body MR tomograph. An extension of the Arrhenius equation with effective base‐catalyzed Arrhenius parameters yielded a general expression for k_sw(pH, T). The defining parameters were identified as the effective base‐catalyzed rate constant k_b,eff(298.15 K) = (3.009 ± 0.16) × 10⁹ Hz l/mol and the effective activation energy E_A,b,eff = (32.27 ± 7.43) kJ/mol at a buffer concentration of c_buffer = (1/15) M. As expected, a strong dependence of k_sw on temperature was observed. The extrapolation of the exchange‐rate constant to in vivo conditions (pH = 7.1, T = 37 °C) led to the value of the exchange‐rate constant k_sw = 1499 Hz. With the explicit function k_sw(pH, T) available, absolute‐pH CEST imaging could be realized and experimentally verified in vitro. By means of our calibration method it is possible to adjust the guanidinium proton exchange‐rate constant k_sw to any desired value by preparing creatine model solutions with a specific pH and temperature. Copyright © 2014 John Wiley & Sons, Ltd.     

Modeling of bioheat equation for skin and a preliminary study on a noninvasive diagnostic method for skin burn wounds

Heat transfer in a unit three-dimensional skin tissue with an embedded vascular system of actual histology structure is computed in the present work. The tissue temperature and the blood temperatures in artery and vein vessels are solved with a multi-grid system. The mean temperature of the tissue over the cross-section of the unit skin area is evaluated. The resulting one-dimensional function is regarded as the temperature of healthy tissue (or injured skin but the blood perfusion is still normally working) for large area of skin in view of the symmetric and periodic structure of the paired artery–vein vessels in nature. A three-dimensional bioheat equation then is formulated by the superposition of the skin burn wound effect and the healthy skin temperature with and without thermal radiation exposure. When this bioheat equation is employed to simulate ADT process on burn wounds, the decaying factor of the skin surface temperature is found to be a sharply decreasing function of time in the self-cooling stage after a thermal radiation heating. Nevertheless, the boundary of non-healing (needing surgery) and healing regions in a large burn wound can be estimated by tracking the peak of the gradient of decaying factor within 30 s after the thermal radiation is turned off. Experimental studies on the full ADT procedure are needed to justify the assumptions in the present computation.     

Neuropsychological predictors of everyday functioning in adults with intellectual disabilities

Background Very little is known about the neuropsychological correlates of adaptive functioning in people with intellectual disabilities (ID). This study examined whether specific cognitive deficits and demographic variables predicted everyday functioning in adults with ID. Method People with ID (n = 101; ages 19–41 years; mean education = 11 years; 34% women; 54% competitively employed; 41% with mild ID) completed a comprehensive neuropsychological battery grouped into four cognitive domains: processing speed, verbal memory and comprehension, visual perception/constructive function, and executive function. In addition, parents completed an 89‐item rating scale developed to assess a wide range of independent living skills. Results Confirmatory factor analysis results confirmed a correlated four‐factor model of cognitive function and a unidimensional model of everyday functioning. Furthermore, structural equation modelling results supported the predictive relationship of verbal memory/comprehension and employment status (standardized regression coefficients 0.45, 0.22, P ≤ 0.01 for each) to measures of everyday functioning. The two variables together explained 35% of the variance in everyday functioning. Conclusions Both general cognitive dysfunction and specific verbal memory and comprehension deficit impair daily functions in people with ID. These findings have implications for predictive models of adaptive functioning, and for cognitive rehabilitation and deficit compensation strategies for this group.     

A structural equation model for age at clinical presentation in nonhomosexual male gender dysphorics

Nonhomosexual male gender dysphorics often make their first requests for clinical assessment when they are in or approaching middle age. This study investigated how well patients' explanations for the timing of these requests fit the objective data. Subjects were 194 outpatients presenting for the first time at a gender identity clinic. Their common explanations for the timing of their requests were incorporated into a formal path model, which was tested using Bentler's structural equations program. The model provided an acceptable fit to the data. The more times a patient has been married and the more children he has fathered, the older he is likely to be when first presenting for clinical attention. This outcome is consistent with the claims of patients that they would have come to a gender clinic sooner if they had not been restrained by commitments to wives and children.     

蛋白核小球藻对邻苯二甲酸二甲酯的富集与降解作用研究

实验结果表明,蛋白核小球藻对邻苯二甲酸二甲酯有明显的富集与降解作用,富集量24h最大达15360μg/g,此后随时间的延长而逐步降低。5天降解率为66.8％。在对实验结果分析的基础上,提出了蛋白核小球藻对邻苯二甲酸二甲酯的二级降解反应动力学方程为-dc/dt=KNr用此方程计算邻苯二甲酸二甲酯浓度与实测值之间的平均相对偏差为1.64％。