Including community composition in biodiversity–productivity models

Studies on biodiversity and ecosystem functioning (BEF) have elicited debate over the interpretation of the positive relationship between species richness and plant productivity. Manipulating richness cannot be achieved without affecting composition; it is thus essential to consider the latter in statistical models.We firstly review existing approaches that use species richness as an explanatory variable and propose modifications to improve their performance. We use an original data set to illustrate the analyses. The classical method where composition is coded as a factor with a level for each different species mixture can be improved by defining the levels using clustering. Methods based on ordinations reduce the dimensionality of plant composition and use the new coordinates as fixed effects; they provide a much better fit to our observations.Secondly, we develop a new method where composition is included as a similarity matrix affecting the residual variance–covariance. Similarity in composition between plots is treated in the same way as shared evolutionary history between species in phylogenetic regression. We find that it outperforms the other models.We discuss the different approaches and suggest that our method is particularly suited for observational studies or for manipulative studies where plant diversity is not kept constant by weeding. By treating species composition in an intuitive and sensible way, it offers a valuable and powerful complement to existing models

The relative contributions of species richness and species composition to ecosystem functioning

How species diversity influences ecosystem functioning has been the subject of many experiments and remains a key question for ecology and conservation biology. However, the fact that diversity cannot be manipulated without affecting species composition makes this quest methodologically challenging. Here, we evaluate the relative importance of diversity and of composition on biomass production, by using partial Mantel tests for one variable while controlling for the other. We analyse two datasets, from the Jena (2002–2008) and the Grandcour (2008–2009) Experiments. In both experiments, plots were sown with different numbers of species to unravel mechanisms underlying the relationship between biodiversity and ecosystem functioning (BEF). Contrary to Jena, plots were neither mowed nor weeded in Grandcour, allowing external species to establish. Based on the diversity–ecosystem functioning and competition theories, we tested two predictions: 1) the contribution of composition should increase with time; 2) the contribution of composition should be more important in non-weeded than in controlled systems. We found support for the second hypothesis, but not for the first. On the contrary, the contribution of species richness became markedly more important few years after the start of the Jena Experiment. This result can be interpreted as suggesting that species complementarity, rather than intraspecific competition, is the driving force in this system. Finally, we explored to what extent the estimated relative importance of both factors varied when measured on different spatial scales of the experiment (in this case, increasing the number of plots included in the analyses). We found a strong effect of scale, suggesting that comparisons between studies, and more generally the extrapolation of results from experiments to natural situations, should be made with caution

The patient experience of in-hospital telemetry monitoring: a qualitative analysis

Aims In-hospital telemetry monitoring has been an integrated part of arrhythmia monitoring for decades. A substantial proportion of patients require arrhythmia monitoring during stays in non-intensive care units. However, studies exploring patients’ experiences of telemetry monitoring are scarce. Therefore, the aim was to explore and describe patients’ experiences of in-hospital telemetry monitoring in a non-intensive care setting. Methods and results Twenty face-to-face, semi-structured interviews were conducted. Interviews were conducted before discharge at two university hospitals in Norway. The patients were purposively sampled, resulting in a well-balanced population comprising 11 men and nine women, mean age 62 years (range 25–83). Average monitoring time was 9 days (range 3–14). Data were audiotaped, transcribed verbatim, and coded using NVivo software. Qualitative content analysis using an inductive approach was performed. Patients expressed a need for individualized information during telemetry monitoring. Their feelings of safety were related to responses from nurses from the central monitoring station when alarms from the telemetry were triggered. Despite perceived physical restrictions and psychological limitations associated with telemetry monitoring, they found monitoring to be beneficial because it facilitated the diagnosis of arrhythmia. Moreover, they expressed a need for improvements in wearable monitoring equipment. Patients expressed ambivalent feelings about discontinuing the telemetry and their readiness for discharge. Conclusion Patients need individualized information about the results of their telemetry monitoring in order to better understand the arrhythmia management and to increase their experience of safety after discharge. The limitations patients experienced should be taken into consideration in further upgrades of telemetry monitoring equipment.publishedVersio

Appropriateness and outcomes of hospitalized patients telemetry monitored for cardiac arrhythmias in accordance with the American Heart Association Practice Standards–A multicenter study

Background To the best of our knowledge, no prospective research studies have compared clinical practice to the American Heart Association (AHA) updated practice standards for in-hospital telemetry monitoring. Objectives Our aims were therefore (1) to investigate how patients were assigned to telemetry monitoring in accordance with the AHA's updated practice standards, (2) to determine the number and type of arrhythmic events, and (3) to describe subsequent changes in clinical management. Methods This prospective multicenter study included 1154 patients at three university hospitals in Norway. Data were collected 24/7 over a four-week period, with follow-up measurements from telemetry admission until hospital discharge. Results Of patients assigned to telemetry, 67 % (n = 767) met practice standards, corresponding to AHA Class I or II. Patients were predominantly men (65 %, n = 748), and the mean age was 65 years (SD ±16). The study included both patients with cardiac and non-cardiac diagnoses from various medical and surgical departments throughout the hospitals. Ninety-one percent of the patients in Class III were monitored based on indications that were reclassified from Class II to Class III (not indicated) in the updated practice standards (patients admitted with chest pain or post-percutaneous coronary intervention (PCI) without complications). Overall, arrhythmic events occurred in 37 % (n = 424) of patients, and they occurred in all classes. Eighteen percent (n = 59) of arrhythmic events occurred in Class III. Of all arrhythmias, 3 % (n = 14) were life threatening, and all of them occurring within Class I. Telemetry monitoring led to changes in clinical management in 22 % (n = 257) of patients due to clinical alarms, of which 71 % (n = 182) were related to medication management. Conclusions Most patients were appropriately monitored according to the AHA practice standards, meeting Class I and II. Arrhythmias occurred in all classes, but life-threatening arrhythmias only occurred in patients in Class I. However, a daily re-assessment of each patient's telemetry indication is warranted.publishedVersio

Defining Metrics for Short Term Success After LVAD Implant: An Analysis of the Society of Thoracic Surgeons Intermacs Registry

Purpose: While clinical trials evaluating left ventricular assist device (LVAD) technology typically use composite outcomes to assess efficacy, composite outcomes including patient reported outcomes (PROs) have not been utilized as benchmarks for LVAD implant center performance improvement initiatives or quality ranking. The objective of the study was to assess the feasibility of generating a patient composite outcome measure including PROs from a real world registry. Methods: Short term (ST, 180 days) adverse events (AEs) and mortality were tallied for Intermacs patients undergoing LVAD implant between 1/2012 and 12/2019. ST postoperative events included mortality on first device and frequencies of stroke, reoperation (device malfunction/other), right heart failure (RHF), prolonged respiratory failure, and/or dialysis on first device. Logistic regression was used to generate odds ratios for mortality for each AE. Separately, the EuroQOL visual analog scale (VAS) was assessed at baseline and 180 days in ST survivors. Results: Of 20,115 patients, 37% suffered at least one event, most commonly death, reoperation and stroke (Table, column A). Stroke, prolonged respiratory failure, and dialysis attributed the most to ST mortality (Table, column B). Of the 16725 patients alive at 180 days, 43% completed a VAS with 82.0% showing VAS improvement. Renal failure and RHF contributed most to failure to improve VAS (Figure). Conclusion: Assessment of a ST composite outcome metric after LVAD implant from a real world data source is feasible but limited by incomplete PRO reporting. ST adverse events display differential effects on mortality and PROs that can be used in development of global rank outcome scores. While reoperation is common, stroke, prolonged respiratory failure and renal failure conferred highest risks of ST deaths within Intermacs. Assessment of PROs should become a priority for LVAD centers to allow the field to generate a complete assessment of patient-centered outcomes

Understanding negative biodiversity–ecosystem functioning relationship in semi-natural wildflower strips

Studies on biodiversity–ecosystem functioning (BEF) in highly controlled experiments often yield results incompatible with observations from natural systems: experimental results often reveal positive relationships between diversity and productivity, while for natural systems, zero or even negative relationships have been reported. The discrepancy may arise due to a limited or closed local species pool in experiments, while natural systems in meta-community contexts experience dynamic processes, i.e., colonization and extinctions. In our study, we analysed plant community properties and above-ground biomass within a semi-natural (i.e., not weeded) experiment in an agricultural landscape. Eleven replicates with four different diversity levels were created from a species pool of 20 wildflower species. We found an overall significant negative relationship between total diversity and productivity. This relationship likely resulted from invasion resistance: in plots sown with low species numbers, we observed colonization by low-performing species; colonization increased species richness but did not contribute substantially to productivity. Interestingly, when analysing the biomass of the sown and the colonizer species separately, we observed in both cases positive BEF relationships, while this relationship was negative for the whole system. A structural equation modelling approach revealed that higher biomass of the sown species was linked to higher species richness, while the positive BEF relationship of the colonizers was indirect and constrained by the sown species biomass. Our results suggest that, in semi-natural conditions common in extensive agroecosystems, the negative BEF relationship results from the interplay between local dominant species and colonization from the regional species pool by subordinate species

Outcomes in patients with gunshot wounds to the brain.

Introduction:Gunshot wounds to the brain (GSWB) confer high lethality and uncertain recovery. It is unclear which patients benefit from aggressive resuscitation, and furthermore whether patients with GSWB undergoing cardiopulmonary resuscitation (CPR) have potential for survival or organ donation. Therefore, we sought to determine the rates of survival and organ donation, as well as identify factors associated with both outcomes in patients with GSWB undergoing CPR. Methods:We performed a retrospective, multicenter study at 25 US trauma centers including dates between June 1, 2011 and December 31, 2017. Patients were included if they suffered isolated GSWB and required CPR at a referring hospital, in the field, or in the trauma resuscitation room. Patients were excluded for significant torso or extremity injuries, or if pregnant. Binomial regression models were used to determine predictors of survival/organ donation. Results:825 patients met study criteria; the majority were male (87.6%) with a mean age of 36.5 years. Most (67%) underwent CPR in the field and 2.1% (n=17) survived to discharge. Of the non-survivors, 17.5% (n=141) were considered eligible donors, with a donation rate of 58.9% (n=83) in this group. Regression models found several predictors of survival. Hormone replacement was predictive of both survival and organ donation. Conclusion:We found that GSWB requiring CPR during trauma resuscitation was associated with a 2.1% survival rate and overall organ donation rate of 10.3%. Several factors appear to be favorably associated with survival, although predictions are uncertain due to the low number of survivors in this patient population. Hormone replacement was predictive of both survival and organ donation. These results are a starting point for determining appropriate treatment algorithms for this devastating clinical condition. Level of evidence:Level II