Prognostic model to predict postoperative acute kidney injury in patients undergoing major gastrointestinal surgery based on a national prospective observational cohort study.

Background: Acute illness, existing co-morbidities and surgical stress response can all contribute to postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery. The aim of this study was prospectively to develop a pragmatic prognostic model to stratify patients according to risk of developing AKI after major gastrointestinal surgery. Methods: This prospective multicentre cohort study included consecutive adults undergoing elective or emergency gastrointestinal resection, liver resection or stoma reversal in 2-week blocks over a continuous 3-month period. The primary outcome was the rate of AKI within 7 days of surgery. Bootstrap stability was used to select clinically plausible risk factors into the model. Internal model validation was carried out by bootstrap validation. Results: A total of 4544 patients were included across 173 centres in the UK and Ireland. The overall rate of AKI was 14·2 per cent (646 of 4544) and the 30-day mortality rate was 1·8 per cent (84 of 4544). Stage 1 AKI was significantly associated with 30-day mortality (unadjusted odds ratio 7·61, 95 per cent c.i. 4·49 to 12·90; P < 0·001), with increasing odds of death with each AKI stage. Six variables were selected for inclusion in the prognostic model: age, sex, ASA grade, preoperative estimated glomerular filtration rate, planned open surgery and preoperative use of either an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Internal validation demonstrated good model discrimination (c-statistic 0·65). Discussion: Following major gastrointestinal surgery, AKI occurred in one in seven patients. This preoperative prognostic model identified patients at high risk of postoperative AKI. Validation in an independent data set is required to ensure generalizability

Recruitment and retention in a multicentre randomised controlled trial in Bell's palsy: A case study

<p>Abstract</p> <p>Background</p> <p>It is notoriously difficult to recruit patients to randomised controlled trials in primary care. This is particularly true when the disease process under investigation occurs relatively infrequently and must be investigated during a brief time window.</p> <p>Bell's palsy, an acute unilateral paralysis of the facial nerve is just such a relatively rare condition. In this case study we describe the organisational issues presented in setting up a large randomised controlled trial of the management of Bell's palsy across primary and secondary care in Scotland and how we managed to successfully recruit and retain patients presenting in the community.</p> <p>Methods</p> <p>Where possible we used existing evidence on recruitment strategies to maximise recruitment and retention. We consider that the key issues in the success of this study were; the fact that the research was seen as clinically important by the clinicians who had initial responsibility for recruitment; employing an experienced trial co-ordinator and dedicated researchers willing to recruit participants seven days per week and to visit them at home at a time convenient to them, hence reducing missed patients and ensuring they were retained in the study; national visibility and repeated publicity at a local level delivered by locally based principal investigators well known to their primary care community; encouraging recruitment by payment to practices and reducing the workload of the referring doctors by providing immediate access to specialist care; good collaboration between primary and secondary care and basing local investigators in the otolarnygology trial centres</p> <p>Results</p> <p>Although the recruitment rate did not meet our initial expectations, enhanced retention meant that we exceeded our planned target of recruiting 550 patients within the planned time-scale.</p> <p>Conclusion</p> <p>While difficult, recruitment to and retention within multi-centre trials from primary care can be successfully achieved through the application of the best available evidence, establishing good relationships with practices, minimising the workload of those involved in recruitment and offering enhanced care to all participants. Primary care trialists should describe their experiences of the methods used to persuade patients to participate in their trials when publishing their results.</p

Evaluation of damages induced by Ga<su>+</sup> - focused ion beam in piezoelectric nanostructures

The impact of Ga+-focused ion beam (FIB) about functional properties of continuous and nanostructured piezoelectric thin films of lead zirconate titanate (Pb(ZrxTi1-x)O3) was investigated. A suitable way to fabricate piezoelectric nanocapacitors was studied, based on the amorphous or crystallized state of the film before etching. Strong modification of structural and electrical behavior for area exposed to ion irradiation is observed when the film is etched in the crystallized state. Both the implantation of Ga+ ions and the film amorphization highlighted by Raman spectroscopy and Kelvin force microscopy analyses can explain this result. The piezoactivity detected by piezoresponse force microscopy is fully destroyed even after a post-annealing treatment. In the case of amorphous etched film, no significant degradation is observed. The latter process is used to successfully fabricate Pb(ZrxTi1-x)O3-based nanocapacitors by means of FIB method. In 50-nm-size capacitors, the local electromechanical behavior is measured at similar level that the one obtained for the un-etched film, evidencing no manifest sidewall effect or FIB-induced damages. This further evidences that amorphous FIB lithography process can reduce the etching damages, demonstrating this is an effective alternative method and very beneficial to pattern such low-dimensional structures, which is a significant result in view of the development of functional nanostructures in the field of nanoelectromechanical systems applications

Electric Clock for NanoMagnet Logic Circuits

Among Field-Coupled technologies, NanoMagnet Logic (NML) is one of the most promising. Low dynamic power consumption, total absence of static power, remarkable heat and radiations resistance, in association with the possibility of combining memory and logic in the same device, make this technology the ideal candidate for low power, portable applications. However, the necessity of using an external magnetic field to locally control the circuit represents, currently, the weakest point of this technology. The high power losses in the clock generation system adopted up to now wipes out the most important advantages of this technology. In this chapter we discuss a clock system based on a piezoelectric actuator that allows electrical control of NanoMagnet Logic circuits. The low power consumption coupled with the fact that electric fields are easier to generate at the nanoscale level makes this clock system a strong candidate as the final and effective clocking mechanism for this technology. Another remarkable advantage of the proposed solution resides in its compatibility with currently available technology