Understanding macroalgal dispersal in a complex hydrodynamic environment: a combined population genetic and physical modelling approach

Gene flow in macroalgal populations can be strongly influenced by spore or gamete dispersal. This, in turn, is influenced by a convolution of the effects of current flow and specific plant reproductive strategies. Although several studies have demonstrated genetic variability in macroalgal populations over a wide range of spatial scales, the associated current data have generally been poorly resolved spatially and temporally. In this study, we used a combination of population genetic analyses and high-resolution hydrodynamic modelling to investigate potential connectivity between populations of the kelp Laminaria digitata in the Strangford Narrows, a narrow channel characterized by strong currents linking the large semi-enclosed sea lough, Strangford Lough, to the Irish Sea. Levels of genetic structuring based on six microsatellite markers were very low, indicating high levels of gene flow and a pattern of isolation-by-distance, where populations are more likely to exchange migrants with geographically proximal populations, but with occasional long-distance dispersal. This was confirmed by the particle tracking model, which showed that, while the majority of spores settle near the release site, there is potential for dispersal over several kilometres. This combined population genetic and modelling approach suggests that the complex hydrodynamic environment at the entrance to Strangford Lough can facilitate dispersal on a scale exceeding that proposed for L. digitata in particular, and the majority of macroalgae in general. The study demonstrates the potential of integrated physical–biological approaches for the prediction of ecological changes resulting from factors such as anthropogenically induced coastal zone changes.

How Outcomes Are Defined in Clinical Trials of Mechanically Ventilated Adults and Children

Systematic reviews have considerable potential to provide evidence-based data to aid clinical decision-making. However, there is growing recognition that trials involving mechanical ventilation lack consistency in the definition and measurement of ventilation outcomes, creating difficulties in combining data for meta-analyses. To address the inconsistency in outcome definitions, international standards for trial registration and clinical trial protocols published recommendations, effectively setting the “gold standard” for reporting trial outcomes. In this Critical Care Perspective, we review the problems resulting from inconsistent outcome definitions and inconsistent reporting of outcomes (outcome sets). We present data highlighting the variability of the most commonly reported ventilation outcome definitions. Ventilation outcomes reported in trials over the last 6 years typically fall into four domains: measures of ventilator dependence; adverse outcomes; mortality; and resource use. We highlight the need, first, for agreement on outcome definitions and, second, for a minimum core outcome set for trials involving mechanical ventilation. A minimum core outcome set would not restrict trialists from measuring additional outcomes, but would overcome problems of variability in outcome selection, measurement, and reporting, thereby enhancing comparisons across trials.

Weaning from mechanical ventilation: a scoping review of qualitative studies

Background; Weaning from mechanical ventilation is influenced by patient, clinician, and organizational factors.

Objective: To identify factors that may influence weaning and adoption of weaning strategies and tools, clinicians’ perceptions of weaning strategies, and weaning experiences of patients and patients’ families.

Method: A scoping review of indexed and nonindexed publications (1990–2012) was done. Qualitative studies of health care providers, patients, and patients’ families involved in weaning were included. Two investigators independently screened 8350 publications and extracted data from 43 studies. Study themes were content analyzed to identify common categories and themes within the categories.

Results: The study sample consisted of nurses in 15 studies, nurses and patients in 1 study, various health care providers in 11, patients in 10, and physicians in 4. Categories identified were as follows: for nurses, role or scope of practice, informing decision making, and influence on weaning outcome; for health care providers, factors influencing weaning decisions or use of protocols, role or scope of practice related to weaning, and organizational structure or practice environment; for patients, experience of mechanical ventilation and weaning, experience of the intensive care environment, psychological phenomena, and enabling success in weaning; and for physicians, tools or factors to facilitate weaning decisions and perceptions of nurses’ role and scope of practice.

Conclusions: Important issues identified were perceived importance of interprofessional collaboration and communication, need to combine subjective knowledge of the patient with objective clinical data, balancing of weaning systematization with individual needs, and appreciation of the physical and psychological work of weaning.