Insights into the pathophysiology of twin–twin transfusion syndrome

Twin–twin transfusion syndrome (TTTS) is attributed to trans-anastomotic transfusion between twins. Anastomoses are ubiquitous in monochorionic (MC) placentae, yet TTTS develops in only 15%. Although ex vivo and in vivo studies fail to identify a unique anastomotic signature, TTTS placentae are typically associated with an imbalance in unidirectional arteriovenous anastomoses with absent bidirectional anastomoses. Doppler detection of an artery-artery anastomosis reduces the chance of TTTS, whereas, in those that develop the disease, it improves stage-independent survival. Selective laser is often curative, but an increasingly recognized risk of persistent or reverse TTTS may be attributable to atypical arteriovenous anastomoses not identifiable from the chorionic plate. Simple dysvolaemia fails to explain several phenotypic features, including haematological concordancy, recipient hypertension, and reversibly absent end diastolic flow in the donor. The renin-angiotensin system is upregulated in the donor and downregulated in the recipient's kidneys, while paradoxically raised renin levels in the recipient may contribute to raised afterload along with endothelin. Although research is limited in humans by therapy and the lack of a suitable experimental model, further studies of placental and vascular pathophysiology may not only refine current treatment modalities but may also, in addition, suggest further avenues for downstream management such as genetic predisposition testing or pharmacological intervention. Copyright © 2005 John Wiley & Sons, Ltd.     

Translation of falls prevention knowledge into action in hospitals: what should be translated and how should it be done?

Introduction

Falls prevention evidence has changed and evolved over time with positive and negative studies revealing that a “one-size fits all” approach is not the solution. Care must be taken to critically appraise the evidence and the potential applicability of that evidence to the specific hospital setting.

Method

A narrative account of the evolution of research evidence in this field is first presented. How this evidence should be applied in clinical practice is challenging, with a lack of translational evidence for the hospital setting we draw on broader theory of translating knowledge to action.

Conclusions

The journey should begin with formation of a management and engagement committee. A review of existing practices and the difference between existing practice and evidence-based practice should be undertaken to identify the “evidence-practice gap.” Engagement with staff is recommended to inform a plan for practice change. Plans for resourcing, targeting, and evaluating these strategies should also be undertaken.

Impact on Industry

This paper will assist hospitals to identify and implement evidence based falls prevention strategies leading to an improvement in patient safety.     

Mercury measurement and control in a CO2-enriched flue gas

Oxycombustion is being considered as a promising solution to carbon capture and sequestration. Standard sampling and measurement methods may or may not be valid under oxycombustion conditions because the flue gas differs significantly from that of conventional air-blown coal combustion.Bench-scale tests were conducted to evaluate the measurement validity of continuous mercury monitors (CMMs), with and without a flue gas preconditioning unit, in a simulated oxycombustion flue gas with varied CO₂ concentrations. Tests also included mercury capture with activated carbon in typical oxyfuel combustion flue gas. Research data indicated that highly concentrated CO₂ streams affect the accuracy of the mass flow rate and the subsequent gaseous mercury measurement, although this is specific to the type of CMM. Concentrated CO₂ streams also induced solid precipitation in the wet-chemistry conversion unit and resulted in a biased measurement of the gas-phase mercury. Flue gas dilution appeared to provide accurate measurement of total gas-phase mercury and be applicable to mercury measurement in highly concentrated CO₂ streams, although mercury speciation appeared to be problematic and will require additional modification and validation. Mercury capture with activated carbon under CO₂-enriched conditions showed similar performance to typical high-acid coal combustion flue gas.